Fermium, Nobelium , Lawrencium , Rutherfordium , Dubnium,Seaborgium

Fermium, Nobelium , Lawrencium , Rutherfordium , Dubnium

Mendelevium is a synthetic element with the symbol Md (formerly Mv) and the atomic number 101. A metallic radioactivetransuranic element in the actinide series, mendelevium is usually synthesized by bombarding einsteinium with alpha particles. It was named after Dmitri Ivanovich Mendeleev, who created the Periodic Table. Sony VAIO VGN-SR290JTQ Battery

Sony VAIO VGN-SR290JVB/C Battery

Mendeleev's periodic system is the fundamental way to classify all the chemical elements. The name "mendelevium" was accepted by the International Union of Pure and Applied Chemistry (IUPAC). On the other hand, the proposed symbol "Mv" submitted by the discoverers was not accepted, and the IUPAC selected "Md" instead. Sony VAIO VGN-SR290JVH/C Battery,Sony VAIO VGN-SR290NTB Battery

Characteristics

Researchers have shown that mendelevium has a moderately stable dipositive (II) oxidation state in addition to the more characteristic (for actinide elements) tripositive (III) oxidation state, the latter being the more dominantly exhibited state in an aqueous solution (chromatography being the process used). Sony VAIO VGN-SR29VN/S Battery

Sometimes, mendelevium can even be shown to exhibit a monopositive (I) state. ²⁵⁶Md has been used to find out some of the chemical properties of this element while in an aqueoussolution. There are no other known uses of mendelevium and only trace amounts of the element have ever been produced. Sony VAIO VGN-SR29XN/S Battery

Sony VAIO VGN-SR2RVN/S Battery

Otherisotopes of mendelevium, all radioactive, have been discovered, with ²⁵⁸Md being the most stable with a two-month half-life (about 55 days). Other isotopes range from 248 to 258 mass numbers and half-lives from a few seconds to about 51 days. The original ²⁵⁶Md had a half-life of 87 minutes. Sony VAIO VGN-SR390NAB Battery

Sony VAIO VGN-SR390NAH Battery

Radioactivity

The radioactivity of the trivalent element, mendelevium, is definitely noteworthy. It was expected that the reaction would be²⁵³Es (?,n) ²⁵⁵Md, where ²⁵⁵Md was ?-active with a t_½ of 5 minutes and the corresponding ?-energy. No such ?-activity was observed, but the 101 fraction showed spontaneous fission representing a t_½ less than 3 hours. Sony VAIO VGN-SR41M/P Battery,Sony VAIO VGN-SR41M/S Battery

Because spontaneous fission was also observed in the fraction containing fermium, the ?-bombardment of ²⁵³Einsteinium (Es) produced ²⁵⁶Md. The latter underwent electron capture to become ²⁵⁶Fermium (Fm), which then decayed by spontaneous fission. So ²⁵⁶Fm was produced by the decays of cyclotron-synthesized mendelevium.^[1] Sony VAIO VGN-SR49VN/H Battery

Metallic state

Johansson and Rosengren predicted in 1975 that Md would prefer a divalent metallic state, similar to europium (Eu) andytterbium(Yb), rather than a trivalent one. Thermochromatographic studies conducted with trace amounts of Md concluded that Md forms a divalent metal. Sony VAIO VGN-SR51B/P Battery

With the aid of empirical correlation method, a divalent metallic radius of (0.194 ± 0.010) nmhas been estimated. The estimated enthalpy of sublimation is in the range of 134-142 kJ/mol.^[2]

Solution chemistry

Before the actual discovery of mendelevium, the trivalent state was the most stable one in aqueous solution. Sony VAIO VGN-SR51B/S Battery

Sony VAIO VGN-SR51MF Battery

Accordingly, a similar chemical behavior to the other 3+ actinides and lanthanides was expected. The elution of Md just before Fm in theelution sequence of the trivalent actinides from the cation-exchange resin column, confirmed this prediction. Afterwards, Md in the form of insoluble hydroxides and fluorides that are quantitatively coprecipitated with trivalent lanthanides was found. Sony VAIO VGN-SR51MF/P Battery

The cation-exchange resin column as well as the HDEHP solvent extraction column elution date is consistent with a trivalent state for Md and an ionic radius smaller than Fm. An ionic radius of 0.0192 nm and a coordination number of 6 for Md³⁺ was predicted using empirical correlations. Sony VAIO VGN-SR51MF/S Battery

Using the known ionic radii for the trivalent rare earths and the linear correlation of log distribution coefficient with ionic radius, an average ionic radius of 0.089 nm was estimated for Md³⁺ and a heat of hydration of – (3654 ± 12) kJ/mol calculated using empirical models and the Born-Haber cycle. Sony VAIO VGN-SR51MF/W Battery

Sony VAIO VGN-SR51MR Battery

In reducing conditions, an anomalous chemical behavior of Md was found. Coprecipitation with BaSO₄and solvent extraction chromatography experiments using HDEHP were carried out in different reducing agents. These showed that Md³⁺ could easily be reduced to a stable Md²⁺ in aqueous solution. Mendelevium can also be reduced to the monovalent state in water-ethanol solutions. Sony VAIO VGN-SR59VG Battery

The cocrystallization of Md⁺ with salts of divalent ions is due to the formation of mixed crystals. For Md⁺, an ionic radius of 0.117 nm was found. The oxidation of Md³⁺ to Md⁴⁺ was rather unsuccessful.^[1] Sony VAIO VGN-SR59VG/H Battery

Mendelevium (for Dimitri Ivanovich Mendeleev, surname commonly transliterated into Latin script as Mendeleev, Mendeleyev, Mendeléef, or even Mendelejeff, and first name sometimes transliterated as Dmitry or Dmitriy) was first synthesized by Albert Ghiorso, Glenn T. Seaborg, Gregory R. Choppin, Bernard G. Harvey, and Stanley G. Thompson (team leader) in early 1955 at the University of California, Berkeley. Sony VAIO VGN-SR70B/S Battery

Sony VAIO VGN-SR72B/P Battery

The team produced ²⁵⁶Md (half-life of 87 minutes) when they bombarded an ²⁵³Es target with alpha particles (helium nuclei) in the Berkeley Radiation Laboratory's 60-inch cyclotron (²⁵⁶Md was the first isotope of any element to be synthesized one atom at a time).^[3] Element 101 was the ninth transuranic element synthesized. Sony VAIO VGN-SR72B/S Battery

The first 17 atoms of this element were created and analyzed using the ion-exchange adsorption-elution method. During the process, mendelevium behaved very much like thulium, its naturally occurring homologue.

Discovery in detail

The discovery was based on a grand total of only 17 atoms. Sony VAIO VGN-SR73JB/S Battery

It is synthesized via the ²⁵³Es (?,n) ²⁵⁶101 reaction in the 60-Inch-Cyclotron (= 152 cm) at Berkeley (California). The target can be produced by irradiation of lighter isotopes as plutonium in the Materials Testing Reactor at the Arco Reactor Station in Idaho. Remarkable is that this target consisted of only 10⁹ atoms of highly radioactive ²⁵³Es (with a half-life of 20.5 days). Sony VAIO VGN-SR74FB/S Battery

Sony VAIO VGN-SR90FS Battery

By elution through a calibrated cation exchange resin column, mendelevium was separated and chemically identified.^[3]

Determining feasibility

To predict if this method would be possible, they made use of a rough calculation. Sony VAIO VGN-SR90NS Battery

The number of atoms that would be produced, would be approximately equal to the number of atoms of target material times its cross section times the ion beam intensity times the time of bombardment related to the half-life of the product when bombarding for a time of the order of its half-life). This gave 1 atom per experiment. Sony VAIO VGN-SR90S Battery

Thus under optimum conditions, the preparation of only one atom of element 101 per experiment could be expected. This calculation demonstrated that it was feasible to go ahead with the experiment.^[3]

Recoil technique

The actual synthesis was done by a recoil technique, introduced by Albert Ghiorso. Sony VAIO VGN-SR90US Battery

In this technique, the target element was placed on the opposite side of the target from the beam and caught the recoiling atoms on a catcher foil. This recoil target was made by an electroplating technique, developed by Alfred Chetham-Strode. This technique gave a very high yield, which is absolutely necessary when working with such a rare product as the einsteinium target material.^[3] Sony VAIO VGN-SR91NS Battery

Sony VAIO VGN-SR91PS Battery

The recoil target consisted of 10^?9 of ²⁵³Es which were deposited electrolytically on a thin gold foil (also Be, Al and Pt can be used). It was bombarded by 41 eV ?-particles in the Berkeley cyclotron with a very high beam density of 6?10¹³ particles per second over an area of 0.05 cm². The target was cooled by water or liquid helium. Sony VAIO VGN-SR91S Battery

The use of helium, in a gaseous atmosphere, slowed down the recoil atoms. This gas could be pumped out of the reaction chamber through a small orifice to form a ‘gas-jet’. Some fraction of the nonvolatile product atoms carried along with the gas, were deposited permanently on the foil surface. The foil could be removed periodically and a new foil could be installed. Sony VAIO VGN-SR91US Battery

Sony VAIO VGN-SR92NS Battery

The next reaction was used for the mendelevium discovery experiment:^{[3][4] 253}Es + ⁴He ? ²⁵⁶Md + ¹n.

Purification and isolation

The removal of the Md atoms from the collector foil was done by acid etching or total dissolution of the thin gold foil. They can be purified and isolated from other product activities by several techniques. Sony VAIO VGN-SR92PS Battery

Sony VAIO VGN-SR92S Battery

Separation of trivalent actinides from lanthanide fission products and La carrier can be done by a cation-exchange resin column using a 90% water/10% ethanol solution saturated with HClas eluant. To separate Md rapidly from the catcher foil, an anion-exchange chromatography using 6M HCl as eluant can be used. The gold remained on the column while the Md and other actinides passed through. Sony VAIO VGN-SR92US Battery

Sony VAIO VGN-SR93DS Battery

A final isolation of Md³⁺ from other trivalent actinides was also required. To separate fractions containing elements 99, 100 and 101, a cation-exchange resin column (Dowex-50 exchange column) treated with ammonium salts was used. A chemical identification was made on the basis of its elution position just before Fm. In series of repetitive experiments, they made use of the eluant: ?-hydroxyisobutyrate solution (?-HIB). Sony VAIO VGN-SR93JS Batery

Sony VAIO VGN-SR93PS Batttery

Using the ‘gas-jet’ method, the first two steps can be eliminated. There was shown that in this method it is possible to transport and collect individual product atoms in a fraction of a second some tens of meters away from the target area. Effective transport over long distances requires the presence of large clusters (KCl aerosols) in the ‘carrier’ gas. It is used frequently in the production and isolation of transeinsteinium elements.^[1] Sony VAIO VGN-SR93YS Battery

Sony VAIO VGN-SR94FS Battery

Another possible way to separate the 3+ actinides can be achieved by solvent extraction chromatography using bis-(2-ethylhexyl) phosphoric acid (abbreviated as HDEHP) as the stationary organic phase and HNO₃ as the mobile aqueous phase. The actinide elution sequence is reversed from that of the cation-exchange resin column. Sony VAIO VGN-SR94GS Battery

The Md separated by this method has the advantage to be free of organic complexing agent compared to the resin column. The disadvantage of this method is that Md elutes after Fm late in the sequence.^[1]

The first "Hooray!"

The data sheet, showing stylus tracing and notes, that proved the discovery of mendelevium. Sony VAIO VGN-SR94HS Battery

Sony VAIO VGN-SR94VS Battery

There was no direct detection, but by observation of spontaneous fission events arising from its electron-capture daughter ²⁵⁶Fm. These events were recorded during the night of February 19, 1955. The first one was identified with a "hooray" followed by a "double hooray" and a "triple hooray". Sony VAIO VGN-SZ35B/B Battery

Sony VAIO VGN-SZ54B/B Battery

The fourth one eventually officially proved the chemical identification of the 101st element, mendelevium. Additional analysis and further experimentation, showed the isotope to have mass 256 and to decay by electron capture with a half-life of 1.5 h. Sony VAIO VGN-SZ55B/B Battery

Sixteen isotopes of mendelevium from mass 245 to 260 have been characterized, with the most stable being ²⁵⁸Md with a half-life of 51.5 days, ²⁶⁰Md with a half-life of 31.8 days, and ²⁵⁷Md with a half-life of 5.52 hours. All of the remaining radioactiveisotopes have half-lives that are less than 97 minutes, and the majority of these have half-lives that are less than 5 minutes. Sony VAIO VGN-SZ55GN/B Battery

Sony VAIO VGN-SZ56 Battery

This element also has 5 meta states, with the longest-lived being ^258mMd (t_½ = 58 minutes). The isotopes of mendelevium range inatomic weight from 245.091 u (²⁴⁵Md) to 260.104 u (²⁶⁰Md).

Nobelium is a synthetic element with the symbol No andatomic number 102. Sony VAIO VGN-SZ561N Battery

It was first correctly identified in 1966 by scientists at the Flerov Laboratory of Nuclear Reactions in Dubna, Soviet Union. Little is known about the element but limited chemical experiments have shown that it forms a stable divalent ion in solution as well as the predicted trivalent ion that is associated with its presence as one of the actinoids. Sony VAIO VGN-SZ562N Battery

Sony VAIO VGN-SZ57N Battery

Discovery profile

The discovery of element 102 was first announced by physicists at the Nobel Institute in Sweden in 1957. The team reported that they created an isotope with a half-life of 10 minutes, decaying by emission of an 8.5 MeV alpha particle, after bombarding ²⁴⁴Cm with ¹³C nuclei. Sony VAIO VGN-SZ58GN Battery

Sony VAIO VGN-SZ58GN/C Battery

The activity was assigned to ²⁵¹No or ²⁵³No. The scientists proposed the name nobelium (No) for the new element. Later they retracted their claim and associated the activity to background effects.

The synthesis of element 102 was then claimed in April 1958 at the University of California, Berkeley by Albert Ghiorso, Glenn T. Seaborg, John R. Walton and Torbjørn Sikkeland. Sony VAIO VGN-SZ58N Battery

Sony VAIO VGN-SZ61MN/B Battery

The team used the new heavy-ion linear accelerator(HILAC) to bombard a curiumtarget (95% ²⁴⁴Cm and 5% ²⁴⁶Cm) with ¹³C and ¹²C ions. They were unable to confirm the 8.5 MeV activity claimed by the Swedes but were instead able to detect decays from ²⁵⁰Fm, supposedly the daughter of²⁵⁴102, which had an apparent half-life of ~3 s. Sony VAIO VGN-SZ61VN/X Battery

In 1959 the team continued their studies and claimed that they were able to produce an isotope that decayed predominantly by emission of an 8.3 MeV alpha particle, with a half-life of 3 s with an associated 30% spontaneous fission branch. The activity was initially assigned to ²⁵⁴No but later changed to ²⁵²No. The Berkeley team decided to adopt the name nobelium for the element. Sony VAIO VGN-SZ61WN/C Battery

Sony VAIO VGN-SZ640N/B Battery

Further work in 1961 on the attempted synthesis of element 103 produced evidence for a Z=102 alpha activity decaying by emission of an 8.2 MeV particle with a half-life of 15 s, and assigned to ²⁵⁵No. Sony VAIO VGN-SZ645P3 Battery

Following initial work between 1958–1964, in 1966, a team at the Flerov Laboratory of Nuclear Reactions (FLNR) reported that they had been able to detect ²⁵⁰Fm from the decay of a parent nucleus (²⁵⁴No) with a half-life of ~50s, in contradiction to the Berkeley claim. Furthermore, they were able to show that the parent decayed by emission of 8.1 MeV alpha particles with a half-life of ~35 s. Sony VAIO VGN-SZ650N/C Battery

Sony VAIO VGN-SZ660N/C Battery

In 1969, the Dubna team carried out chemical experiments on element 102 and concluded that it behaved as the heavier homologue of ytterbium. The Russian scientists proposed the name joliotium (Jo) for the new element.

Later work in 1967 at Berkeley and 1971 at Oak Ridge fully confirmed the discovery of element 102 and clarified earlier observations. Sony VAIO VGN-SZ670N/C Battery

Sony VAIO VGN-SZ680ND Battery

In 1992, the IUPAC-IUPAP Transfermium Working Group (TWG) assessed the claims of discovery and concluded that only the Dubna work from 1966 correctly detected and assigned decays to Z=102 nuclei at the time. The Dubna team are therefore officially recognised as the discoverers of nobelium although it is possible that it was detected at Berkeley in 1959. Sony VAIO VGN-SZ691N/X Battery

Sony VAIO VGN-SZ71E/B Battery

Naming

Element 102 was first named nobelium (No) by its claimed discoverers in 1957 by scientists at the Nobel Institute in Sweden. The name was later adopted by Berkeley scientists who claimed its discovery in 1959. Sony VAIO VGN-SZ71VN/X Battery

The International Union of Pure and Applied Chemistry (IUPAC) officially recognised the name nobelium following the Berkeley results.

In 1994, and subsequently in 1997, the IUPAC ratified the name nobelium (No) for the element on the basis that it had become entrenched in the literature over the course of 30 years and that Alfred Nobel should be commemorated in this fashion. Sony VAIO VGN-SZ71WN/C Battery,Sony VAIO VGN-SZ74B/B Battery

Physical properties

The appearance of this element is unknown, however it is most likely silvery-white or gray and metallic. If sufficient amounts of nobelium were produced, it would pose a radiation hazard. Some sources quote a melting point of 827 °C for nobelium but this cannot be substantiated from an official source and seems implausible regarding the requirements of such a measurement. Sony VAIO VGN-SZ750N/C Battery

Sony VAIO VGN-SZ75B/B Battery

However, the 1st, 2nd and 3rd ionization energies have been measured^{[citation needed]}. In addition, an electronegativity value of 1.3 is also sometimes quoted.

Aqueous phase chemistry

First experiments involving nobelium assumed that it predominantly formed a +III state like earlier actinoids. Sony VAIO VGN-SZ76 Battery

However, it was later found that nobelium forms a stable +II state in solution, although it can be oxidised to an oxidising +III state.^[1] A reduction potential of ?1.78 V has been measured for the No³⁺ ion. The hexaaquanobelium(II) ion has been determined to have an ionic radius of 110 pm. Sony VAIO VGN-SZ770N/C Battery

Sony VAIO VGN-SZ77N Battery

Summary of compounds and (complex) ions

Twelve radioisotopes of nobelium have been characterized, with the most stable being ²⁵⁹No with a half-life of 58 minutes. Longer half-lives are expected for the as-yet-unknown ²⁶¹No and ²⁶³No. An isomeric level has been found in ²⁵³No and K-isomers have been found in ²⁵⁰No, ²⁵²No and ²⁵⁴No to date. Sony VAIO VGN-SZ780 Battery,Sony VAIO VGN-SZ78N Battery,Sony VAIO VGN-SZ791N/X Battery

Synthesis of isotopes as decay products

Isotopes of nobelium have also been identified in the decay of heavier elements. Observations to date are summarised in the table below:

Isomerism in nobelium nuclides

²⁵⁴No The study of K-isomerism was recently studied by physicists at the University of Jyväskylä physics laboratory (JYFL). Sony VAIO VGN-SZ84NS Battery

Sony VAIO VGN-SZ84PS Battery

They were able to confirm a previously reported K-isomer and detected a second K-isomer. They assigned spins and parities of 8^- and 16⁺to the two K-isomers.

²⁵³No In 1971, Bemis et al. was able to determine an isomeric level decaying with a half-life of 31 µs from the decay of ²⁵⁷Rf. Sony VAIO VGN-SZ84S Battery

Sony VAIO VGN-SZ84US Battery

This was confirmed in 2003 at the GSI by also studying the decay of ²⁵⁷Rf. Further support in the same year from the FLNR appeared with a slightly higher half-life of 43.5 µs, decaying by M2 gamma emission to the ground state.

²⁵²No In a recent study by the GSI into K-isomerism in even-even isotopes, a K-isomer with a half-life of 110 ms was detected for ²⁵²No. Sony VAIO VGN-SZ85NS Battery

Sony VAIO VGN-SZ85S Battery

A spin and parity of 8^- was assigned to the isomer.

²⁵⁰No In 2003, scientists at the FLNR reported that they had been able to synthesise ²⁴⁹No which decayed by SF with a half-life of 54µs. Further work in 2006 by scientists at the ANL showed that the activity was actually due to a K-isomer in ²⁵⁰No. The ground state isomer was also detected with a very short half-life of 3.7µs. Sony VAIO VGN-SZ85US Battery,Sony VAIO VGN-SZ94NS Battery

Cold fusion

The table below provides cross-sections and excitation energies for cold fusion reactions producing nobelium isotopes directly. Data in bold represents maxima derived from excitation function measurements. + represents an observed exit channel. Sony VAIO VGN-SZ94PS Battery

Sony VAIO VGN-SZ94S Battery

Hot fusion

The table below provides cross-sections and excitation energies for hot fusion reactions producing nobelium isotopes directly. Data in bold represents maxima derived from excitation function measurements. + represents an observed exit channel. Sony VAIO VGN-SZ94US Battery?Sony VAIO VGN-SZ95NS Battery

Retracted isotopes

In 2003, scientists at the FLNR claimed to have discovered the lightest known isotope of nobelium. However, subsequent work showed that the 54 µs activity was actually due to ²⁵⁰No and the isotope ²⁴⁹No was retracted. Sony VAIO VGN-SZ95S Battery

Sony VAIO VGN-SZ95US Battery

Lawrencium is a radioactive synthetic chemical element with the symbol Lr and atomic number 103. In the periodic table of the elements, it is a period 7 d-block element and the last element of actinideseries. Chemistry experiments have confirmed that lawrencium behaves as the heavier homologue to lutetium and is chemically similar to other actinides. Sony VAIO VGN-TZ121 Battery,Sony VAIO VGN-TZ13 Battery

Lawrencium was first synthesized by the nuclear-physics team led by Albert Ghiorso on February 14, 1961, at theLawrence Berkeley National Laboratory of the University of California. Sony VAIO VGN-TZ130N/B Battery

The first atoms of lawrencium were produced by bombarding a three-milligram target consisting of three isotopes of the element californium with boron-10 and boron-11 nuclei from the Heavy Ion Linear Accelerator. The team suggested the name lawrencium, and the symbol Lw, but Lr was officially accepted instead. It was the last element of actinide series produced. Sony VAIO VGN-TZ131 Battery,Sony VAIO VGN-TZ132/N Battery

All isotopes of lawrencium are radioactive; its most stable known isotope is lawrencium-262, with a half-life of approximately 3.6 hours. All its isotopes except for lawrencium-260, -261 and -262 decay with a half-life of less than a minute. Sony VAIO VGN-TZ132N Battery

Discovery

Lawrencium was first synthesized by the nuclear-physics team of Albert Ghiorso, Torbjørn Sikkeland, Almon Larsh, Robert M. Latimer, and their co-workers on February 14, 1961, at the Lawrence Radiation Laboratory (now called theLawrence Berkeley National Laboratory) at the University of California. Sony VAIO VGN-TZ150N/B Battery

The first atoms of lawrencium were produced by bombarding a three-milligramtarget consisting of three isotopes of the element californium with boron-10 and boron-11nuclei from the Heavy Ion Linear Accelerator (HILAC).^[1] The Berkeley team reported that the isotope ²⁵⁷Lr was detected in this manner, and that it decayed by emitting an 8.6 MeV alpha particle with a half-life of about eight seconds. Sony VAIO VGN-TZ150N/N Battery?Sony VAIO VGN-TZ160CB Battery

This identification was later corrected to be ²⁵⁸Lr.^[1]

In 1967, nuclear-physics researchers in Dubna, Russia, reported that they were not able to confirm assignment of an alpha emitter with a half-life of eight seconds to ²⁵⁷Lr.^[2] This isotope was later deduced to be ²⁵⁸Lr. Instead, the Dubna team reported an isotope with a half-life of about 45 seconds as ²⁵⁶Lr.^[3] Sony VAIO VGN-TZ160N/B Battery?Sony VAIO VGN-TZ16GN/B Battery

Further experiments have demonstrated an actinide chemistry for the new element, so by 1970 it was known that lawrencium is an actinide, and what is more, the last one.^[4] In 1971, the nuclear physics team at the University of California at Berkeley successfully performed a whole series of experiments aimed at measuring the nuclear decay properties of the lawrencium isotopes with mass numbers from 255 through 260.^[5] Sony VAIO VGN-TZ16N Battery,Sony VAIO VGN-TZ16N/B Battery

In 1992, the IUPAC Trans-fermium Working Group (TWG) officially recognized the nuclear physics teams at Dubna and Berkeley as the co-discoverers of lawrencium.^[6]

Naming

The origin of the name, ratified by the American Chemical Society, is in reference to the nuclear-physicist Ernest O. Lawrence, of the University of California, who invented the cyclotron particle accelerator. Sony VAIO VGN-TZ17/N Battery?Sony VAIO VGN-TZ170N/B Battery

The symbol Lw was used originally,^[1] but the element was assigned the Lr symbol.^[6] In August 1997, the International Union of Pure and Applied Chemistry (IUPAC) ratified the name lawrencium and the symbol Lr during a meeting in Geneva.^[6] Sony VAIO VGN-TZ170N/N Battery

Electronic structure

Lawrencium is element 103 in the periodic table. It is the first member of the 6d-block; in accordance with theMadelung rule, its electronic configuration should be [Rn]7s²5f¹⁴6d¹. However, results from quantum mechanical research have suggested that this configuration is incorrect, and is in fact [Rn]7s²5f¹⁴7p¹. Sony VAIO VGN-TZ17GN/B Battery?Sony VAIO VGN-TZ17N Battery

A direct measurement of this is not possible. Though early calculations gave conflicting results,^[7] more recent studies and calculations confirm the suggestion.^[8][9]

A strict correlation between the periodic table blocks and the orbital-shell configurations for neutral atoms would classify lawrencium as a transition metal because it could be classed as a d-block element. Sony VAIO VGN-TZ18/N Battery?Sony VAIO VGN-TZ180N/RC Battery

However, lawrencium is classified as an actinide element according to the IUPAC

Experimental chemical properties

The first gaseous-phase studies of lawrencium were reported in 1969 by a nuclear-physics team at the FlerovLaboratory of Nuclear Reactions (FLNR) in the Soviet Union. Sony VAIO VGN-TZ185N/WC Battery

Sony VAIO VGN-TZ18GN/X Battery

They used the nuclear reaction ²⁴³Am+¹⁸O to produce lawrencium nuclei, which they then exposed to a stream of chlorine gas, and a volatile chloride product was formed. This product was deduced to be ²⁵⁶LrCl₃, and this confirmed that lawrencium is a typical actinide element.^[11] Sony VAIO VGN-TZ18N Battery

Aqueous phase

The first aqueous-phase studies of lawrencium were reported in 1970 by a nuclear-physics team at the Lawrence Berkeley National Laboratory in California. This team used the nuclear reaction ²⁴⁹Cf+¹¹B to produce lawrencium nuclei. Sony VAIO VGN-TZ190N/B Battery

They were able to show that lawrencium forms a trivalent ion, similar to those of the other actinide elements, but in contrast with that of nobelium. Further experiments in 1988 confirmed the formation of a trivalent lawrencium(III) ion using anion-exchange chromatography using ?-hydroxyisobutyrate (?-HIB) complex. Sony VAIO VGN-TZ190N/BC Battery

Comparison of the elution time with other actinides allowed a determination of 88.6 picometers for the ionic radius for Lr³⁺. Attempts to reduce lawrencium in the lawrencium(III) ionization state to lawrencium(I) using the potent reducing agent hydroxylamine hydrochloride were unsuccessful. Sony VAIO VGN-TZ191N/XC Battery

Sony VAIO VGN-TZ195N/XC Battery,Sony VAIO VGN-TZ198N/RC Battery

²⁰⁵Tl(⁵⁰Ti,xn)^255-xLr (x=2?)

This reaction was studied in a series of experiments in 1976 by Yuri Oganessian and his team at the FLNR. Evidence was provided for the formation of ²⁵³Lr in the 2n exit channel. Sony VAIO VGN-TZ250N/B Battery

²⁰³Tl(⁵⁰Ti,xn)^253-xLr

This reaction was studied in a series of experiments in 1976 by Yuri Oganessian and his team at the FLNR.

²⁰⁸Pb(⁴⁸Ti,pxn)^255-xLr (x=1?)

This reaction was reported in 1984 by Yuri Oganessian at the FLNR. The team was able to detect decays of ²⁴⁶Cf, a descendant of ²⁵⁴Lr. Sony VAIO VGN-TZ250N/N Battery

²⁰⁸Pb(⁴⁵Sc,xn)^253-xLr

This reaction was studied in a series of experiments in 1976 by Yuri Oganessian and his team at the FLNR. Results are not readily available.

²⁰⁹Bi(⁴⁸Ca,xn)^257-xLr (x=2)

This reaction has been used to study the spectroscopic properties of ²⁵⁵Lr. Sony VAIO VGN-TZ250N/P Battery

The team at GANIL used the reaction in 2003 and the team at the FLNR used it between 2004-2006 to provide further information for the decay scheme of ²⁵⁵Lr. The work provided evidence for an isomeric level in ²⁵⁵Lr.

Hot fusion

This reaction was first studied in 1965 by the team at the FLNR. They were able to detect activity with a characteristic decay of 45 seconds, which was assigned to²⁵⁶Lr or ²⁵⁷Lr. Sony VAIO VGN-TZ27/N Battery

Sony VAIO VGN-TZ270N/B Battery

Later work suggests an assignment to ²⁵⁶Lr. Further studies in 1968 produced an 8.35–8.60 MeV alpha activity with a half-life of 35 seconds. This activity was also initially assigned to ²⁵⁶Lr or ²⁵⁷Lr and later to solely ²⁵⁶Lr.

²⁴³Am(¹⁶O,xn)^259-xLr (x=4)

This reaction was studied in 1970 by the team at the FLNR. They were able to detect an 8.38 MeV alpha activity with a half-life of 20s. This was assigned to ²⁵⁵Lr. Sony VAIO VGN-TZ27N Battery

Sony VAIO VGN-TZ28/N Battery

²⁴⁸Cm(¹⁵N,xn)^263-xLr (x=3,4,5)

This reaction was studied in 1971 by the team at the LBNL in their large study of lawrencium isotopes. They were able to assign alpha activities to ²⁶⁰Lr,²⁵⁹Lr and²⁵⁸Lr from the 3-5n exit channels. Sony VAIO VGN-TZ285N/RC Battery

²⁴⁸Cm(¹⁸O,pxn)^265-xLr (x=3,4)

This reaction was studied in 1988 at the LBNL in order to assess the possibility of producing ²⁶²Lr and ²⁶¹Lr without using the exotic ²⁵⁴Es target. It was also used to attempt to measure an electron capture (EC) branch in ^261mRf from the 5n exit channel. Sony VAIO VGN-TZ28N Battery

After extraction of the Lr(III) component, they were able to measure thespontaneous fission of ²⁶¹Lr with an improved half-life of 44 minutes. The production cross-section was 700 pb. On this basis, a 14% electron capture branch was calculated if this isotope was produced via the 5n channel rather than the p4n channel. Sony VAIO VGN-TZ290EAB Battery,Sony VAIO VGN-TZ290EAN Battery

A lower bombarding energy (93 MeV c.f. 97 MeV) was then used to measure the production of ²⁶²Lr in the p3n channel. The isotope was successfully detected and a yield of 240 pb was measured. The yield was lower than expected compared to the p4n channel. Sony VAIO VGN-TZ290EAP Battery

However, the results were judged to indicate that the ²⁶¹Lr was most likely produced by a p3n channel and an upper limit of 14% for the electron capture branch of ^261mRf was therefore suggested.

²⁴⁶Cm(¹⁴N,xn)^260-xLr (x=3?)

This reaction was studied briefly in 1958 at the LBNL using an enriched ²⁴⁴Cm target (5% ²⁴⁶Cm). Sony VAIO VGN-TZ295N/XC Battery

Sony VAIO VGN-TZ298N/XC Battery

They observed a ~9 MeV alpha activity with a half-life of ~0.25 seconds. Later results suggest a tentative assignment to ²⁵⁷Lr from the 3n channel

²⁴⁴Cm(¹⁴N,xn)^258-xLr

This reaction was studied briefly in 1958 at the LBNL using an enriched ²⁴⁴Cm target (5% ²⁴⁶Cm). They observed a ~9 MeV alpha activity with a half-life of ~0.25s. Sony VAIO VGN-TZ33/B Battery

Sony VAIO VGN-TZ33/N Battery

Later results suggest a tentative assignment to ²⁵⁷Lr from the 3n channel with the ²⁴⁶Cm component. No activities assigned to reaction with the ²⁴⁴Cm component have been reported.

²⁴⁹Bk(¹⁸O,?xn)^263-xLr (x=3)

This reaction was studied in 1971 by the team at the LBNL in their large study of lawrencium isotopes. They were able to detect an activity assigned to ²⁶⁰Lr. Sony VAIO VGN-TZ33/W Battery

Sony VAIO VGN-TZ350N/B Battery

The reaction was further studied in 1988 to study the aqueous chemistry of lawrencium. A total of 23 alpha decays were measured for ²⁶⁰Lr, with a mean energy of 8.03 MeV and an improved half-life of 2.7 minutes. The calculated cross-section was 8.7 nb. Sony VAIO VGN-TZ350N/N Battery

²⁵²Cf(¹¹B,xn)^263-xLr (x=5,7??)

This reaction was first studied in 1961 at the University of California by Albert Ghiorso by using a californium target (52% ²⁵²Cf). They observed three alpha activities of 8.6, 8.4 and 8.2 MeV, with half-lives of about 8 and 15 seconds, respectively. Sony VAIO VGN-TZ350N/P Battery

The 8.6 MeV activity was tentatively assigned to ²⁵⁷Lr. Later results suggest a reassignment to ²⁵⁸Lr, resulting from the 5n exit channel. The 8.4 MeV activity was also assigned to ²⁵⁷Lr. Later results suggest a reassignment to ²⁵⁶Lr. This is most likely from the 33% ²⁵⁰Cf component in the target rather than from the 7n channel. The 8.2 MeV was subsequently associated with nobelium. Sony VAIO VGN-TZ370N/B Battery

Sony VAIO VGN-TZ37N/G Battery

²⁵²Cf(¹⁰B,xn)^262-xLr (x=4,6)

This reaction was first studied in 1961 at the University of California by Albert Ghiorso by using a californium target (52% ²⁵²Cf). They observed three alpha activities of 8.6, 8.4 and 8.2 MeV, with half-lives of about 8 and 15 seconds, respectively. Sony VAIO VGN-TZ37N/P Battery

The 8.6 MeV activity was tentatively assigned to ²⁵⁷Lr. Later results suggest a reassignment to ²⁵⁸Lr. The 8.4 MeV activity was also assigned to ²⁵⁷Lr. Later results suggest a reassignment to ²⁵⁶Lr. The 8.2 MeV was subsequently associated with nobelium. Sony VAIO VGN-TZ37N/R Battery

²⁵⁰Cf(¹⁴N,?xn)^260-xLr (x=3)

This reaction was studied in 1971 at the LBNL. They were able to identify a 0.7s alpha activity with two alpha lines at 8.87 and 8.82 MeV. This was assigned to²⁵⁷Lr.

²⁴⁹Cf(¹¹B,xn)^260-xLr (x=4)

This reaction was first studied in 1970 at the LBNL in an attempt to study the aqueous chemistry of lawrencium. Sony VAIO VGN-TZ37N/X Battery

Sony VAIO VGN-TZ38N/X Battery

They were able to measure a Lr³⁺ activity. The reaction was repeated in 1976 at Oak Ridge and 26s ²⁵⁶Lr was confirmed by measurement of coincident X-rays.

²⁴⁹Cf(¹²C,pxn)^260-xLr (x=2)

This reaction was studied in 1971 by the team at the LBNL. They were able to detect an activity assigned to ²⁵⁸Lr from the p2n channel. Sony VAIO VGN-TZ398U/XC Battery

Sony VAIO VGN-TZ50B Battery

²⁴⁹Cf(¹⁵N,?xn)^260-xLr (x=2,3)

This reaction was studied in 1971 by the team at the LBNL. They were able to detect an activities assigned to ²⁵⁸Lr and ²⁵⁷Lr from the ?2n and ?3n and channels. The reaction was repeated in 1976 at Oak Ridge and the synthesis of ²⁵⁸Lr was confirmed. Sony VAIO VGN-TZ90HS Battery

²⁵⁴Es + ²²Ne – transfer

This reaction was studied in 1987 at the LLNL. They were able to detect new spontaneous fission (SF) activities assigned to ²⁶¹Lr and ²⁶²Lr, resulting from transfer from the ²²Ne nuclei to the ²⁵⁴Es target. In addition, a 5 ms SF activity was detected in delayed coincidence with nobelium K-shell X-rays and was assigned to ²⁶²No, resulting from the electron capture of ²⁶²Lr. Sony VAIO VGN-TZ90NS Battery

Sony VAIO VGN-TZ90S Battery

Decay products

Isotopes of lawrencium have also been identified in the decay of heavier elements. Observations to date are summarised in the table below:

Eleven isotopes of lawrencium plus one isomer have been synthesized with ²⁶²Lr being the longest-lived and the heaviest, with a half-life of 216 minutes. Sony VAIO VPC CW2MFX/PU Battery

²⁵²Lr is the lightest isotope of lawrencium to be produced to date.

Lawrencium-253

A study of the decay properties of ²⁵⁷Db (see dubnium) in 2001 by Hessberger et al. at the GSI provided some data for the decay of ²⁵³Lr. Analysis of the data indicated the population of two isomeric levels in ²⁵³Lr from the decay of the corresponding isomers in ²⁵⁷Db. Sony VAIO VPC S11V9E/B Battery

The ground state was assigned spin and parity of 7/2-, decaying by emission of an 8794 KeV alpha particle with a half-lifeof 0.57s. The isomeric level was assignedspin and parity of 1/2-, decaying by emission of an 8722 KeV alpha particle with a half-lifeof 1.49 s. Sony VAIO VPCB119GJ/B Battery

Rutherfordium is a chemical element with symbol Rf and atomic number 104, named in honor of New Zealand physicist Ernest Rutherford. It is a synthetic element (an element that can be created in a laboratory but is not found in nature) and radioactive; the most stable known isotope, ²⁶⁷Rf, has a half-life of approximately 1.3 hours. Sony VAIO VPCB11AGJ Battery,Sony VAIO VPCB11AVJ Battery

In the periodic table of the elements, it is a d-block element and the first of the transactinide elements. It is a member of the 7th period and belongs to the group 4 elements. Chemistry experiments have confirmed that rutherfordium behaves as the heavier homologue to hafnium in group 4. Sony VAIO VPCB11V9E Battery,Sony VAIO VPCB11X9E Battery

The chemical properties of rutherfordium are characterized only partly. They compare well with the chemistry of the other group 4 elements, even though some calculations had indicated that the element might show significantly different properties due to relativistic effects. Sony VAIO VPCCW18FJ/P Battery

In the 1960s, small amounts of rutherfordium were produced in laboratories in the former Soviet Union and in California. The priority of the discovery and therefore the naming of the element was disputed between Soviet and American scientists, and it was not until 1997 that International Union of Pure and Applied Chemistry (IUPAC) established rutherfordium as the official name for the element. Sony VAIO VPCCW18FJ/R Battery,Sony VAIO VPCCW18FJ/W Battery

Discovery

Rutherfordium was reportedly first detected in 1966 at the Joint Institute of Nuclear Research at Dubna (then in theSoviet Union). Researchers there bombarded a plutonium-242 target with neon-22 ions and separated the reaction products by gradient thermochromatography after conversion to chlorides by interaction with ZrCl₄. Sony VAIO VPCCW19FJ/W Battery?Sony VAIO VPCCW1AFJ Battery

The team identified spontaneous fission activity contained within a volatile chloride portraying eka-hafnium properties. Although a half-life was not accurately determined, later calculations indicated that the product was most likely rutherfordium-259 (or simply²⁵⁹Rf):^[4] Sony VAIO VPCCW1AHJ Battery

In 1969, researchers at the University of California, Berkeley conclusively synthesized the element by bombarding acalifornium-249 target with carbon-12 ions and measured the alpha decay of ²⁵⁷Rf, correlated with the daughter decay ofnobelium-253:^[5] Sony VAIO VPCCW1S1E Battery

The American synthesis was independently confirmed in 1973 and secured the identification of rutherfordium as the parent by the observation of K-alpha X-rays in the elemental signature of the ²⁵⁷Rf decay product, nobelium-253. ^[6] Sony VAIO VPCCW1S1E/B Battery

Naming controversy

The 104th element was eventually named after Ernest Rutherford (left side) (1871–1937), a British-New Zealand chemist and physicist who became known as the father of nuclear physics. Sony VAIO VPCCW1S1E/L Battery

The element was initially proposed to be named after Igor Kurchatov(right side) (1903–1960), a Soviet nuclear physicist who is remembered as "The Father of the Soviet Atomic Bomb".

The Russian scientists proposed the name kurchatovium and the American scientists suggested the name rutherfordium for the new element.^[7] Sony VAIO VPCCW1S1E/P Battery

In 1992, the IUPAC/IUPAPTransfermium Working Group (TWG) assessed the claims of discovery and concluded that both teams provided contemporaneous evidence to the synthesis of element 104 and that credit should be shared between the two groups.^[4]

The American group wrote a scathing response to the findings of the TWG, stating that they had given too much emphasis on the results from the Dubna group. Sony VAIO VPCCW1S1E/R Battery

Sony VAIO VPCCW1S1E/W Battery

In particular they pointed out that the Russian group had altered the details of their claims several times over a period of 20 years, a fact that the Russian team does not deny. They also stressed that the TWG had given too much credence to the chemistry experiments performed by the Russians and accused the TWG of not having appropriately qualified personnel on the committee. Sony VAIO VPCCW21FX/B Battery

Sony VAIO VPCCW21FX/L Battery

The TWG responded by saying that this was not the case and having assessed each point raised by the American group said that they found no reason to alter their conclusion regarding priority of discovery.^[8] The IUPAC finally used the name suggested by the American team (rutherfordium) which may in some way reflect a change of opinion.^[9] Sony VAIO VPCCW21FX/R Battery

As a consequence of the initial competing claims of discovery, an element naming controversy arose. Since the Soviets claimed to have first detected the new element they suggested the name kurchatovium, Ku, in honor of Igor Kurchatov (1903–1960), former head of Soviet nuclear research. Sony VAIO VPCCW21FX/W Battery

Sony VAIO VPCCW26EC Battery

This name had been used in books of the Soviet Bloc as the official name of the element. The Americans, however, proposed rutherfordium (Rf) for the new element to honor Ernest Rutherford, who is known as the "father" ofnuclear physics. Sony VAIO VPCCW26FX/B Battery

The International Union of Pure and Applied Chemistry (IUPAC) adopted unnilquadium, Unq, as a temporary, systematic element name, derived from the Latin names for digits 1, 0, and 4. In 1994, IUPAC suggested the name dubnium to be used since rutherfordium was suggested for element 106 and IUPAC felt that the Dubna team should be rightly recognized for their contributions. Sony VAIO VPCCW28EC Battery?Sony VAIO VPCCW28FJ/P Battery

However, there was still a dispute over the names of elements 104–107. In 1997 the teams involved resolved the dispute and adopted the current name rutherfordium. The name dubnium was given to element 105 at the same time.^[9] Sony VAIO VPCCW28FJ/R Battery

The chemical properties of rutherfordium were based on calculation which indicated that the relativistic effects on the electron shell might be strong enough that the p orbitals have a lower energy level than the d orbitals and therefore the element more behaves like lead. Sony VAIO VPCCW28FJ/W Battery

With better calculation methods and studies of the chemical properties of rutherfordium compounds it could be shown that rutherfordium behaves according to the rest of the group 4 elements.^[10]

Nucleosynthesis

Super-heavy elements such as rutherfordium are produced by bombarding lighter elements in particle accelerators that induces fusion reactions. Sony VAIO VPCCW29FJ/W Battery,Sony VAIO VPCCW2AFJ Battery

Whereas most of the isotopes of rutherfordium can be synthesized directly this way, some heavier ones have only been observed as decay products of elements with higher atomic numbers.^[11]

Depending on the energies involved, the former are separated into "hot" and "cold".Sony VAIO VPCCW2AHJ Battery

In hot fusion reactions, very light, high-energy projectiles are accelerated toward very heavy targets (actinides), giving rise to compound nuclei at high excitation energy (~40–50 MeV) that may either fission or evaporate several (3 to 5) neutrons.^[11] In cold fusion reactions, the produced fused nuclei have a relatively low excitation energy (~10–20 MeV), which decreases the probability that these products will undergo fission reactions. Sony VAIO VPCCW2S1E Battery

Sony VAIO VPCCW2S1E/B Battery

As the fused nuclei cool to the ground state, they require emission of only one or two neutrons, and thus, allows for the generation of more neutron-rich products.^[12] The latter is a distinct concept from that of where nuclear fusion claimed to be achieved at room temperature conditions (see cold fusion).^[13] Sony VAIO VPCCW2S1E/L Battery

Sony VAIO VPCCW2S1E/P Battery

Hot fusion studies

The synthesis of rutherfordium was first attempted in 1964 by the team at Dubna using the hot fusion reaction of neon-22 projectiles with plutonium-242 targets:

The first study produced evidence for a spontaneous fission with a 0.3 second half-life and another one at 8 seconds. Sony VAIO VPCCW2S1E/R Battery

Sony VAIO VPCCW2S1E/W Battery

While the former observation was eventually retracted, the latter eventually became associated with the ²⁵⁹Rf isotope.^[4] In 1966, the Soviet team repeated the experiment using a chemical study of volatile chloride products. They identified a volatile chloride with eka-hafnium properties that decayed fast through spontaneous fission. Sony VAIO VPCCW2S5C CN1 Battery?Sony VAIO VPCF112FX/B Battery

This gave strong evidence for the formation of RfCl₄, and although a half-life was not accurately measured, later evidence suggested that the product was most likely ²⁵⁹Rf. The team repeated the experiment several times over the next few years, and in 1971, they revised the spontaneous fission half time for the isotope at 4.5 seconds.^[4] Sony VAIO VPCF115FG/B Battery,Sony VAIO VPCF116FGBI Battery

In 1969, researchers at the University of California led by Albert Ghiorso, tried to confirm the original results reported at Dubna. In a reaction of curium-248 withoxygen-16, they were unable to confirm the result of the Soviet team, but managed to observe the spontaneous fission of ²⁶⁰Rf with a very short half-life of 10–30 ms: Sony VAIO VPCF117FJ/W Battery?Sony VAIO VPCF117HG/BI Battery

In 1970, team also studied the same reaction with oxygen-18 and identified ²⁶¹Rf with a half-life of 65 seconds (later refined to 75 seconds).^[14][15] Later experiments at the Lawrence Berkeley National Laboratory in California also revealed the formation of a short-lived isomer of ²⁶²Rf (which undergoes spontaneous fission with a half-life of 47 ms),^[16] and spontaneous fission activities with long lifetimes tentatively assigned to ²⁶³Rf.^[17] Sony VAIO VPCF118FJ/W Battery,Sony VAIO VPCF119FC Battery

Diagram of the experimental set-up used in the discovery of isotopes ²⁵⁷Rf and ²⁵⁹ Rf

The reaction of californium-249 with carbon-13 was also investigated by the Ghiorso team, which indicated the formation of the short-lived ²⁵⁸Rf (which undergoes spontaneous fission in 11 ms):^[5] Sony VAIO VPCF119FC/BI Battery?Sony VAIO VPCF119FJ/BI Battery

In trying to confirm these results by using carbon-12 instead, they also observed the first alpha decays from²⁵⁷Rf.^[5]

The reaction of berkelium-249 with nitrogen-14 was first studied in Dubna in 1977, and in 1985, researchers there confirmed the formation of the ²⁶⁰Rf isotope which quickly undergoes spontaneous fission in 28 ms:^[4] Sony VAIO VPCF11AFJ Battery,Sony VAIO VPCF11AGJ Battery

In 1996 the isotope ²⁶²Rf was observed in LBNL from the fusion of plutonium-244 with neon-22:

The team determined a half-life of 2.1 seconds, in contrast to earlier reports of 47 ms and suggested that the two half-lives might be due to different isomeric states of ²⁶²Rf.^[18] Sony VAIO VPCF11AHJ Battery

Sony VAIO VPCF11JFX/B Battery

Studies on the same reaction by a team at Dubna, lead to the observation in 2000 of alpha decays from ²⁶¹Rf and spontaneous fissions of ^261mRf.^[19]

The hot fusion reaction using a uranium target was first reported at Dubna in 2000:

They observed decays from ²⁶⁰Rf and ²⁵⁹Rf, and later for ²⁵⁹Rf. In 2006, as part of their program on the study of uranium targets in hot fusion reactions, the team at LBNL also observed ²⁶¹Rf.^[19][20][21] Sony VAIO VPCF11M1E Battery

Sony VAIO VPCF11M1E/H Battery

Cold fusion studies

The first cold fusion experiments involving element 104 were done in 1974 at Dubna, by using light titanium-50 nuclei aimed at lead-208 isotope targets:

The measurement of a spontaneous fission activity was assigned to ²⁵⁶Rf,^[22] while later studies done at the Gesellschaft für Schwerionenforschung Institute (GSI), also measured decay properties for the isotopes ²⁵⁷Rf, and ²⁵⁵Rf.^[23][24] Sony VAIO VPCF11MFX/B Battery?Sony VAIO VPCF11S1E Battery

In 1974 researchers at Dubna investigated the reaction of lead-207 with titanium-50 to produce the isotope ²⁵⁵Rf.^[25] In a 1994 study at GSI using the lead-206 isotope, ²⁵⁵Rf as well as ²⁵⁴Rf were detected. ²⁵³Rf was similarly detected that year when lead-204 was used instead.^[24] Sony VAIO VPCF11S1E/B Battery

Decay studies

Most isotopes with an atomic mass below 262 have also observed as decay products of elements with a higher atomic number, allowing for refinement of their previously measured properties. Heavier isotopes of rutherfordium have only been observed as decay products. Sony VAIO VPCF11Z1E Battery

For example, a few alpha decay events terminating in ²⁶⁷Rf were observed in the decay chain of darmstadtium-279 since 2004:

This further underwent spontaneous fission with a half-time of about 1.3 h.^[26][27][28]

Investigations on the synthesis of the dubnium-263 isotope in 1999 at the University of Bern revealed events consistent with electron capture to form ²⁶³Rf. Sony VAIO VPCF11Z1E/BI Battery

A rutherfordium fraction was separated, and several spontaneous fission events with long lifetimes of about 15 minutes were observed, as well as and alpha decays with lifetimes of about 10 minutes.^[17] Reports on the decay chain of ununquadium-285 in 2010 showed five sequential alpha decays that terminate in ²⁶⁵Rf, which further undergoes spontaneous fission with a life-time of 152 seconds.^[3] Sony VAIO VPCF11ZHJ Battery,Sony VAIO VPCF127HGBI Battery

Some experimental evidence was obtained in 2004 for an even heavier isotope, ²⁶⁸Rf, in the decay chain of an isotope of ununpentium:

However, the last step in this chain was uncertain. After observing the five alpha decay events that generate dubnium-268, spontaneous fission events were observed with a long half-time. Sony VAIO VPCF137HG/BI Battery,Sony VAIO VPCS111FM/S Battery

It is unclear whether these events were due to direct spontaneous fission of ²⁶⁸Db, or ²⁶⁸Db produced electron capture events with long half-times to generate ²⁶⁸Rf. If the latter is produced and decays with a short life-time, the two possibilities cannot be distinguished.^[29] Sony VAIO VPCS115EC Battery

Given that the electron capture of ²⁶⁸Db cannot be detected, these spontaneous fission events may be due to ²⁶⁸Rf, in which case the half-life of this isotope cannot be extracted.^[30][31]

A 2007 report on the synthesis of ununtrium, the isotope ²⁸²113 was observed to undergo a similar decay to form ²⁶⁶Db, which undergoes spontaneous fission with a half-life of 22 minutes. Sony VAIO VPCS115FG Battery,Sony VAIO VPCS117GG Battery

Given that the electron capture of ²⁶⁶Db cannot be detected, these spontaneous fission events may be due to ²⁶⁶Rf, in which case the half-life of this isotope cannot be extracted.^[32][33]

Rutherfordium has no stable or naturally-occurring isotopes. Several radioactive isotopes have been synthesized in the laboratory, either by fusing two atoms or by observing the decay of heavier elements. Sony VAIO VPCS117GGB Battery?Sony VAIO VPCS118EC Battery

Fifteen different isotopes have been reported with atomic masses from 253 to 268 (with the exception of 264). Most of these decay predominantly through spontaneous fission pathways.^[2][34]

Life-times

The lighter isotopes usually have shorter half-lives; Sony VAIO VPCS119FJ/B Battery

Sony VAIO VPCS119GC Battery

half-lives of under 50 ?s for ²⁵³Rf and ²⁵⁴Rf were observed. ²⁵⁶Rf, ²⁵⁸Rf, ²⁶⁰Rf are more stable at around 10 ms, ²⁵⁵Rf, ²⁵⁷Rf, ²⁵⁹Rf, and ²⁶²Rf live between 1 and 5 seconds, and ²⁶¹Rf, ²⁶⁵Rf, and ²⁶³Rf are more stable, at around 1, 1.5, and 10 min, respectively. The heaviest isotopes are the most stable, with ²⁶⁷Rf having a measured half-life of about 1.3 h.^[2] Sony VAIO VPCS11AFJ Battery

The lightest isotopes were synthesized by direct fusion between two lighter nuclei and as decay products. The heaviest isotope produced by direct fusion is ²⁶²Rf; heavier isotopes have only been observed as decay products of elements with larger atomic numbers, of which only ²⁶⁷Rf has been confirmed. Sony VAIO VPCS11AGJ Battery

Isotopes ²⁶⁶Rf and²⁶⁸Rf may have also been observed as decay products and are thought to have long half-lives of 10 h and 6 h, respectively—but these have been measured indirectly, through systematic studies. While the isotopes ²⁶⁴Rf and ²⁶⁵Rf have yet to be observed, they are predicted to have long half-lives of 1 and 13h, respectively.^[2] Sony VAIO VPCS11AHJ Battery

In 1999, American scientists at the University of California, Berkeley, announced that they had succeeded in synthesizing three atoms of ²⁹³118.^[35] These parent nuclei were reported to have successively emitted seven alpha particles to form ²⁶⁵Rf nuclei, but their claim was retracted in 2001.^[36] Sony VAIO VPCS11AVJ Battery

Nuclear isomerism

Several early studies on the synthesis of ²⁶³Rf have indicated that this nuclide decays primarily by spontaneous fission with a half-life of 10–20 minutes. More recently, a study of hassium isotopes allowed the synthesis of atoms of ²⁶³Rf decaying with a shorter half-life of 8 seconds. Sony VAIO VPCS11J7E/B Battery

These two different decay modes must be associated with two isomeric states, but specific assignments are difficult due to the low number of observed events.^[17]

During research on the synthesis of rutherfordium isotopes utilizing the ²⁴⁴Pu(²²Ne,5n)²⁶¹Rf reaction, the product was found to undergo exclusive 8.28 MeV alpha decay with a half-life of 78 seconds. Sony VAIO VPCS11M1E/W Battery,Sony VAIO VPCS11V9E Battery

Later studies at GSI on the synthesis of copernicium and hassium isotopes produced conflicting data, as ²⁶¹Rf produced in the decay chain was found to undergo 8.52 MeV alpha decay with a half-life of 4 seconds. Later results indicated a predominant fission branch. These contradictions led to some doubt on the discovery of copernicium. Sony VAIO VPCS11V9E/B Battery

The first isomer is currently denoted ^261aRf whilst the second is denoted ^261bRf. However, it is thought that the first nucleus belongs to a high-spin ground state and the latter to a low-spin metastable state.^[38] The discovery and confirmation of ^261bRf provided proof for the discovery of copernicium in 1996.^[39] Sony VAIO VPCS11X9E/B Battery

A detailed spectroscopic study of the production of ²⁵⁷Rf nuclei using the reaction ²⁰⁸Pb(⁵⁰Ti,n)²⁵⁷Rf allowed the identification of an isomeric level in ²⁵⁷Rf. The work confirmed that ^257gRf has a complex spectrum with 15 alpha lines. A level structure diagram was calculated for both isomers.^[40] Similar isomers were reported for ²⁵⁶Rf also.^[41] Sony VAIO VPCS123FGB Battery

As group 4 element

Rutherfordium is the first transactinide element and the first member of the 6d series of transition metals. Calculations on itsionization potentials, atomic radius, as well as radii, orbital energies, and ground levels of its ionized states are similar to that of hafnium and much different from that of lead. Sony VAIO VPCS125EC Battery,Sony VAIO VPCS128EC Battery

Therefore it was concluded that rutherfordium's basic properties will resemble those of other group 4 elements, below titanium, zirconium, and hafnium.^[10][17] Some of its properties were determined by gas-phase experiments and aqueous chemistry. The oxidation state +4 is the only stable state for the latter two elements and therefore rutherfordium should also exhibit a stable +4 state.^[10] Sony VAIO VPCS129GC Battery?Sony VAIO VPCS12C7E/B Battery

In an analogous manner to zirconium and hafnium, rutherfordium is projected to form a very stable, high melting point oxide, RfO₂. It reacts with halogens to form tetrahalides, RfX₄, which hydrolyze on contact with water to form oxyhalides RfOX₂. The tetrahalides are volatile solids existing as monomeric tetrahedral molecules in the vapor phase.^[10] Sony VAIO VPCS12L9E/B Battery

In the aqueous phase, the Rf⁴⁺ ion hydrolyzes less than titanium(IV) and to a similar extent as zirconium and hafnium, thus resulting in the RfO²⁺ ion. Treatment of the halides with halide ions promotes the formation of complex ions. The use of chloride and bromide ion produces the hexahalide complexes RfCl₆^2? and RfBr₆^2?. Sony VAIO VPCS12V9E/B Battery?Sony VAIO VPCY115FGS Battery

For the fluoride complexes, zirconium and hafnium tend to form hepta- and octa- complexes. Thus, for the larger rutherfordium ion, the complexes RfF₆^2?, RfF₇^3? and RfF₈^4? are possible.^[10] Sony VAIO VPCY115FX/BI Battery

Gas phase

Early work on the study of the chemistry of rutherfordium focused on gas thermochromatography and measurement of relative deposition temperature adsorption curves. The initial work was carried out at Dubna in an attempt to reaffirm their discovery of the element. Sony VAIO VPCY115FXBI Battery

Recent work is more reliable regarding the identification of the parent rutherfordium radioisotopes. The isotope ^261mRf has been used for these studies. The experiments relied on the expectation that rutherfordium would begin the new 6d series of elements and should therefore form a volatile tetrachloride due to the tetrahedral nature of the molecule. Sony VAIO VPCY118EC Battery,Sony VAIO VPCY118GX/BI Battery

A series of experiments confirmed that rutherfordium behaves as a typical member of group 4, forming a tetravalent chloride (RfCl₄) and bromide (RfBr₄) as well as an oxychloride (RfOCl₂). A decreased volatility was observed for RfCl₄ when potassium chloride is provided as the solid phase instead of glass, highly indicative of the formation of nonvolatile K₂RfCl₆ mixed salt.^[10][17][43] Sony VAIO VPCY119FJ/S Battery

Sony VAIO VPCY11AFJ Battery

Aqueous phase

Rutherfordium is expected to have the electron configuration [Rn]5f¹⁴ 6d² 7s² and therefore behave as the heavier homologue of hafnium in group 4 of the periodic table. It should therefore readily form a hydrated Rf⁴⁺ ion in strong acid solution and should readily form complexes inhydrochloric acid, hydrobromic or hydrofluoric acid solutions.^[10] Sony VAIO VPCY11AGJ Battery,Sony VAIO VPCY11AHJ Battery

The most conclusive aqueous chemistry studies of rutherfordium have been performed by the Japanese team at Japan Atomic Energy Research Instituteusing the radioisotope ^261mRf. Extraction experiments from hydrochloric acid solutions using isotopes of rutherfordium, hafnium, zirconium, and thorium have proved a non-actinide behavior. Sony VAIO VPCY11AVJ Battery

A comparison with its lighter homologues placed rutherfordium firmly in group 4 and indicated the formation of a hexachlororutherfordate complex in chloride solutions, in a manner similar to hafnium and zirconium.^[10][44]

Very similar results were observed in hydrofluoric acid solutions. Sony VAIO VPCY11M1E/S Battery

Differences in the extraction curves were interpreted as a weaker affinity for fluoride ion and the formation of the hexafluororutherfordate ion, whereas hafnium and zirconium ions complex seven or eight fluoride ions at the concentrations used.

Dubnium ,^[4] is a chemical element with the symbol Db and atomic number 105, named after the town of Dubna in Russia, where it was first produced. Sony VAIO VPCY11S1E Battery?Sony VAIO VPCY11V9E/S Battery

It is a synthetic element (an element that can be created in a laboratory but is not found in nature) and radioactive; the most stable known isotope, dubnium-268, has a half-life of approximately 28 hours.^[5]

In the periodic table of the elements, it is a d-block element and in the transactinide elements. Sony VAIO VPCY218EC/BI Battery

It is a member of the7th period and belongs to the group 5 element. Chemistry experiments have confirmed that dubnium behaves as the heavier homologue to tantalumin group 5. The chemical properties of dubnium are characterized only partly. They are similar with those of other group 5 elements. Sony VAIO VPCY218EC/G Battery

In the 1960s, microscopic amounts of dubnium were produced in laboratories in the former Soviet Union and in California. The priority of the discovery and therefore the naming of the element was disputed between Soviet and American scientists, and it was not until 1997 that International Union of Pure and Applied Chemistry (IUPAC) established Soviet team priority and a compromise name of dubnium as the official name for the element. Sony VAIO VPCY218EC/L Battery

Discovery

Dubnium was reportedly first discovered in 1968 at the Joint Institute for Nuclear Research at Dubna (then in the Soviet Union). Researchers there bombarded an americium-243 target with neon-22 ions. They reported a 9.40 MeV and a 9.70 MeV alpha-activity and assigned the decays to the isotope ²⁶⁰Db or ²⁶¹Db: Sony VAIO VPCY218EC/P Battery?Sony VAIO VPCY21S1E/L Battery

Two years later the Dubna team separated their reaction products by thermal gradient chromatography after conversion to chlorides by interaction with NbCl₅. The team identified a 2.2 second spontaneous fission activity contained within a volatile chloride portraying eka-tantalum properties, likely dubnium-261 pentachloride, ²⁶¹DbCl₅. Sony VAIO VPCY21S1E/P Battery

In the same year, a team led by Albert Ghiorso working at the University of California, Berkeley conclusively synthesized the element by bombarding a californium-249 target with nitrogen-15 ions. published a convincing synthesis of ²⁶⁰Db in the reaction between californium-249 target and nitrogen-15 ions and measured the alpha decay of ²⁶⁰Db with a half-life of 1.6 seconds and a decay energy of 9.10 MeV, correlated with the daughter decay of lawrencium-256: Sony VAIO VPCY21S1E/SI Battery?Sony VAIO VPCCW2S5C CN1 Battery

These results by the Berkeley scientists did not confirm the Soviet findings regarding the 9.40 MeV or 9.70 MeV alpha-decay of dubnium-260, leaving only dubnium-261 as possible produced isotope. In 1971, the Dubna team repeated their reaction using an improved set-up and were able to confirm the decay data for²⁶⁰Db using the reaction: Sony VAIO VPCEA20 Battery,Sony VAIO VPCEB10 Battery

In 1976, the Dubna team continued their study of the reaction using thermal gradient chromatography and were able to identify the product as dubnium-260 pentabromide, ²⁶⁰DbBr₅. Sony VAIO VPCEB11FM Battery

In 1992 the IUPAC/IUPAP Transfermium Working Group assessed the claims of the two groups and concluded that confidence in the discovery grew from results from both laboratories and the claim of discovery should be shared.^[6] Sony VAIO VPCEB11FM/BI Battery

Naming controversy

The element 105 was originally proposed to be named after Niels Bohr(left side), a Danish nuclear physicist, with name nielsbohrium(Ns) by the Soviet/Russian team. The American team initially proposed the element to be named after Otto Hahn(right side), a German chemist, known as a pioneer in the fields ofradioactivity and radiochemistry. Sony VAIO VPCEB11FM/T Battery

Sony VAIO VPCEB11FM/WI Battery

The Soviet (later, Russian) team proposed the name nielsbohrium (Ns) in honor of the Danish nuclear physicist Niels Bohr. The American team proposed that the new element should be named hahnium (Ha), in honor of the late German chemist Otto Hahn. Sony VAIO VPCEB11FX Battery

Consequently hahnium was the name that most American and Western European scientists used and appears in many papers published at the time, and nielsbohrium was used in the Soviet Union and Eastern Bloc countries.

An element naming controversy erupted between the two groups. Sony VAIO VPCEB11FX/BI Battery

The International Union of Pure and Applied Chemistry (IUPAC) thus adopted unnilpentium (Unp) as a temporary, systematic element name. Attempting to resolve the issue, in 1994, the IUPAC proposed the name joliotium (Jl), after the French physicist Frédéric Joliot-Curie, which was originally proposed by Soviet team for element 102, later named nobelium. Sony VAIO VPCEB11FX/T Battery,Sony VAIO VPCEB11FX/WI Battery

The two principal claimants still disagreed about the names of elements 104-106. However, in 1997 they resolved the dispute and adopted the current name, dubnium (Db), after the Russian town of Dubna, the location of the Joint Institute for Nuclear Research. Sony VAIO VPCEB11GX Battery

It was argued by IUPAC that the Berkeley laboratory had already been recognized several times in the naming of elements (i.e., berkelium, californium, americium) and that the acceptance of the names rutherfordiumand seaborgium for elements 104 and 106 should be offset by recognizing the Russian team's contributions to the discovery of elements 104, 105 and 106.^[7][8] Sony VAIO VPCEB11GX/BI Battery,Sony VAIO VPCEB11GX/T Battery

Extrapolated properties

Element 105 is projected to be the second member of the 6d series of transition metals and the heaviest member of group V in the Periodic Table, below vanadium, niobium and tantalum. Because it is positioned right below tantalum, it may also be calledeka-tantalum. Sony VAIO VPCEB11GX/WI Battery

All the members of the group readily portray their oxidation state of +5 and the state becomes more stable as the group is descended. Thus dubnium is expected to form a stable +5 state. For this group, +4 and +3 states are also known for the heavier members and dubnium may also form these reducing oxidation states. Sony VAIO VPCEB12FX Battery

In an extrapolation of the chemistries from niobium and tantalum, dubnium should react with oxygen to form an inert pentoxide, Db₂O₅. In alkali, the formation of an orthodubnate complex, DbO₄^3?, is expected. Reaction with the halogens should readily form the pentahalides, DbX₅. Sony VAIO VPCEB12FX/BI Battery

The pentachlorides of niobium and tantalum exist as volatile solids or monomeric trigonal bipyramidal molecules in the vapour phase. Thus, DbCl₅ is expected to be a volatile solid. Similarly, the pentafluoride, DbF₅, should be even more volatile. Hydrolysis of the halides is known to readily form the oxyhalides, MOX₃. Sony VAIO VPCEB12FX/BIC Battery

Thus the halides DbX₅ should react with water to form DbOX₃. The reaction with fluoride ion is also well known for the lighter homologues and dubnium is expected to form a range of fluoro-complexes. In particular, reaction of the pentafluoride with HF should form a hexafluorodubnate ion, DbF₆^–. Excess fluoride should lead to DbF₇^2– and DbOF₅^2–. Sony VAIO VPCEB12FX/T Battery

Sony VAIO VPCEB14FX Battery

If eka-tantalum properties are portrayed, higher concentrations of fluoride should ultimately form DbF₈^3– since NbF₈^3– is not known.

Experimental chemistry

The chemistry of dubnium has been studied for several years using gas thermochromatography. Sony VAIO VPCEB14FX/BI Battery

The experiments have studied the relative adsorption characteristics of isotopes of niobium, tantalum and dubnium radioisotopes. The results have indicated the formation of typical group 5 halides and oxyhalides, namely DbCl₅, DbBr₅, DbOCl₃ and DbOBr₃. Reports on these early experiments usually refer to dubnium as hahnium. Sony VAIO VPCEB14FX/T Battery

Cold fusion

This section deals with the synthesis of nuclei of dubnium by so-called "cold" fusion reactions. These are processes which create compound nuclei at low excitation energy (~10-20 MeV, hence "cold"), leading to a higher probability of survival from fission. The excited nucleus then decays to the ground state via the emission of one or two neutrons only. Sony VAIO VPCEB14FX/WI Battery

Sony VAIO VPCEB15FM Battery

²⁰⁹Bi(⁵⁰Ti,xn)^259-xDb (x=1,2,3)

The first attempts to synthesise dubnium using cold fusion reactions were performed in 1976 by the team at FLNR, Dubna using the above reaction. They were able to detect a 5 s spontaneous fission (SF) activity which they assigned to ²⁵⁷Db. This assignment was later corrected to ²⁵⁸Db. Sony VAIO VPCEB15FM/BI Battery

Sony VAIO VPCEB15FM/T Battery

In 1981, the team at GSI studied this reaction using the improved technique of correlation of genetic parent-daughter decays. They were able to positively identify ²⁵⁸Db, the product from the 1n neutron evaporation channel.^[9] In 1983, the team at Dubna revisited the reaction using the method of identification of a descendant using chemical separation. Sony VAIO VPCEB15FM/WI Battery

Sony VAIO VPCEB15FX Battery

They succeeded in measuring alpha decays from known descendants of the decay chain beginning with ²⁵⁸Db. This was taken as providing some evidence for the formation of dubnium nuclei. The team at GSI revisited the reaction in 1985 and were able to detect 10 atoms of ²⁵⁷Db.^[10] Sony VAIO VPCEB15FX/BI Battery

After a significant upgrade of their facilities in 1993, in 2000 the team measured 120 decays of ²⁵⁷Db, 16 decays of ²⁵⁶Db and decay of ²⁵⁸Db in the measurement of the 1n, 2n and 3n excitation functions. The data gathered for ²⁵⁷Db allowed a first spectroscopic study of this isotope and identified an isomer, ^257mDb, and a first determination of a decay level structure for ²⁵⁷Db.^[11] Sony VAIO VPCEB15FX/T Battery

Sony VAIO VPCEB15FX/WI Battery

The reaction was used in spectroscopic studies of isotopes of mendelevium and einsteinium in 2003-2004.<sup>[12]

209</sup>Bi(⁴⁹Ti,xn)^258-xDb (x=2?)

This reaction was studied by Yuri Oganessian and the team at Dubna in 1983. Sony VAIO VPCEB16FX Battery

They observed a 2.6 s SF activity tentatively assigned to ²⁵⁶Db. Later results suggest a possible reassignment to ²⁵⁶Rf, resulting from the ~30% EC branch in ²⁵⁶Db.

²⁰⁹Bi(⁴⁸Ti,xn)^257-xDb (x=1?)

This reaction was studied by Yuri Oganessian and the team at Dubna in 1983. Sony VAIO VPCEB16FX/B Battery

They observed a 1.6 s activity with a ~80% alpha branch with a ~20% SF branch. The activity was tentatively assigned to ²⁵⁵Db. Later results suggest a reassignment to ²⁵⁶Db.

²⁰⁸Pb(⁵¹V,xn)^259-xDb (x=1,2)

The team at Dubna also studied this reaction in 1976 and were again able to detect the 5 s SF activity, first tentatively assigned to ²⁵⁷Db and later to ²⁵⁸Db. Sony VAIO VPCEB16FX/G Battery

In 2006, the team at LBNL reinvestigated this reaction as part of their odd-Z projectile program. They were able to detect ²⁵⁸Db and ²⁵⁷Db in their measurement of the 1n and 2n neutron evaporation channels.<sup>[13]

207</sup>Pb(⁵¹V,xn)^258-xDb

The team at Dubna also studied this reaction in 1976 but this time they were unable to detect the 5 s SF activity, first tentatively assigned to ²⁵⁷Db and later to²⁵⁸Db. Instead, they were able to measure a 1.5 s SF activity, tentatively assigned to ²⁵⁵Db. Sony VAIO VPCEB16FX/L Battery

Sony VAIO VPCEB16FX/P Battery

²⁰⁵Tl(⁵⁴Cr,xn)^259-xDb (x=1?)

The team at Dubna also studied this reaction in 1976 and were again able to detect the 5 s SF activity, first tentatively assigned to ²⁵⁷Db and later to ²⁵⁸Db.

Hot fusion

This section deals with the synthesis of nuclei of dubnium by so-called "hot" fusion reactions. Sony VAIO VPCEB16FX/W Battery

These are processes which create compound nuclei at high excitation energy (~40-50 MeV, hence "hot"), leading to a reduced probability of survival from fission and quasi-fission. The excited nucleus then decays to the ground state via the emission of 3-5 neutrons. Sony VAIO VPCEB17FX Battery

²³²Th(³¹P,xn)^263-xDb (x=5)

There are very limited reports that this rare reaction using a P-31 beam was studied in 1989 by Andreyev et al. at the FLNR. One source suggests that no atoms were detected whilst a better source from the Russians themselves indicates that ²⁵⁸Db was synthesised in the 5n channel with a yield of 120 pb. Sony VAIO VPCEB17FX/B Battery

²³⁸U(²⁷Al,xn)^265-xDb (x=4,5)

In 2006, as part of their study of the use of uranium targets in superheavy element synthesis, the LBNL team led by Ken Gregorich studied the excitation functions for the 4n and 5n channels in this new reaction.^[14] Sony VAIO VPCEB17FX/G Battery

²³⁶U(²⁷Al,xn)^263-xDb (x=5,6)

This reaction was first studied by Andreyev et al. at the FLNR, Dubna in 1992. They were able to observe ²⁵⁸Db and ²⁵⁷Db in the 5n and 6n exit channels with yields of 450 pb and 75 pb, respectively.^[15] Sony VAIO VPCEB17FX/L Battery

²⁴³Am(²²Ne,xn)^265-xDb (x=5)

The first attempts to synthesise dubnium were performed in 1968 by the team at the Flerov Laboratory of Nuclear Reactions (FLNR) in Dubna, Russia. They observed two alpha lines which they tentatively assigned to ²⁶¹Db and ²⁶⁰Db. They repeated their experiment in 1970 looking for spontaneous fission. Sony VAIO VPCEB17FX/P Battery

Sony VAIO VPCEB17FX/W Battery

They found a 2.2 s SF activity which they assigned to ²⁶¹Db. In 1970, the Dubna team began work on using gradient thermochromatography in order to detect dubnium in chemical experiments as a volatile chloride. In their first run they detected a volatile SF activity with similar adsorption properties to NbCl₅ and unlike HfCl₄. Sony VAIO VPCEB190X Battery

This was taken to indicate the formation of nuclei of dvi-niobium as DbCl₅. In 1971, they repeated the chemistry experiment using higher sensitivity and observed alpha decays from an dvi-niobium component, taken to confirm the formation of ²⁶⁰105. The method was repeated in 1976 using the formation of bromides and obtained almost identical results, indicating the formation of a volatile, dvi-niobium-like [105]Br₅. Sony VAIO VPCEB19FX Battery?Sony VAIO VPCEB19GX Battery

²⁴¹Am(²²Ne,xn)^263-xDb (x=4,5)

In 2000, Chinese scientists at the Institute of Modern Physics (IMP), Lanzhou, announced the discovery of the previously unknown isotope ²⁵⁹Db formed in the 4n neutron evaporation channel. They were also able to confirm the decay properties for ²⁵⁸Db.^[16] Sony VAIO VPCEB1AFX Battery

²⁴⁸Cm(¹⁹F,xn)^267-xDb (x=4,5)

This reaction was first studied in 1999 at the Paul Scherrer Institute (PSI) in order to produce ²⁶²Db for chemical studies. Just 4 atoms were detected with a cross section of 260 pb.^[17] Sony VAIO VPCEB1AFX/B Battery

Japanese scientists at JAERI studied the reaction further in 2002 and determined yields for the isotope ²⁶²Db during their efforts to study the aqueous chemistry of dubnium.<sup>[18]

249</sup>Bk(¹⁸O,xn)^267-xDb (x=4,5)

Following from the discovery of ²⁶⁰Db by Albert Ghiorso in 1970 at the University of California (UC), the same team continued in 1971 with the discovery of the new isotope ²⁶²Db. Sony VAIO VPCEB1AGX Battery,Sony VAIO VPCEB1AGX/BI Battery

They also observed an unassigned 25 s SF activity, probably associated with the now-known SF branch of ²⁶³Db.^[19] In 1990, a team led by Kratz at LBNL definitively discovered the new isotope ²⁶³Db in the 4n neutron evaporation channel.^[20] This reaction has been used by the same team on several occasions in order to attempt to confirm an electron capture (EC) branch in ²⁶³Db leading to long-lived ²⁶³Rf (see rutherfordium).^[21] Sony VAIO VPCEB1BGX Battery?Sony VAIO VPCEB1BGX/BI Battery

²⁴⁹Bk(¹⁶O,xn)^265-xDb (x=4)

Following from the discovery of ²⁶⁰Db by Albert Ghiorso in 1970 at the University of California (UC), the same team continued in 1971 with the discovery of the new isotope ²⁶¹Db.<sup>[19]

250</sup>Cf(¹⁵N,xn)^265-xDb (x=4)

Following from the discovery of ²⁶⁰Db by Ghiorso in 1970 at LBNL, the same team continued in 1971 with the discovery of the new isotope ²⁶¹Db.^[19] Sony VAIO VPCEB1CGX Battery?Sony VAIO VPCEB1CGX/BI Battery

²⁴⁹Cf(¹⁵N,xn)^264-xDb (x=4)

In 1970, the team at the Lawrence Berkeley National Laboratory (LBNL) studied this reaction and identified the isotope ²⁶⁰Db in their discovery experiment. They used the modern technique of correlation of genetic parent-daughter decays to confirm their assignment.^[22] Sony VAIO VPCEB1DGX Battery

In 1977, the team at Oak Ridge repeated the experiment and were able to confirm the discovery by the identification of K X-rays from the daughter lawrencium.<sup>[23]

254</sup>Es(¹³C,xn)^267-xDb

In 1988, scientists as the Lawrence Livermore National Laboratory (LLNL) used the asymmetric hot fusion reaction with an einsteinium-254 target to search for the new nuclides ²⁶⁴Db and ²⁶³Db. Sony VAIO VPCEB1DGX/BI Battery

Sony VAIO VPCEB1EGX Battery

Due to the low sensitivity of the experiment caused by the small Es-254 target,they were unable to detect any evaporation residues (ER).

Decay of heavier nuclides

Isotopes of dubnium have also been identified in the decay of heavier elements. Observations to date are summarised in the table below: Sony VAIO VPCEB1EGX/BI Battery,Sony VAIO VPCEB1FGX Battery

²⁶⁰Db

Recent data on the decay of ²⁷²Rg has revealed that some decay chains continue through ²⁶⁰Db with extraordinary longer life-times than expected. These decays have been linked to an isomeric level decaying by alpha decay with a half-life of ~19 s. Further research is required to allow a definite assignment. Sony VAIO VPCEB1FGX/BI Battery

²⁵⁸Db

Evidence for an isomeric state in ²⁵⁸Db has been gathered from the study of the decay of ²⁶⁶Mt and ²⁶²Bh. It has been noted that those decays assigned to an electron capture (EC) branch has a significantly different half-life to those decaying by alpha emission. This has been taken to suggest the existence of an isomeric state decaying by EC with a half-life of ~20 s. Sony VAIO VPCEB1GGX Battery,Sony VAIO VPCEB1GGX/BI Battery

Further experiments are required to confirm this assignment.

²⁵⁷Db

A study of the formation and decay of ²⁵⁷Db has proved the existence of an isomeric state. Initially, ²⁵⁷Db was taken to decay by alpha emission with energies 9.16,9.07 and 8.97 MeV. A measurement of the correlations of these decays with those of ²⁵³Lr have shown that the 9.16 MeV decay belongs to a separate isomer. Sony VAIO VPCEB1HGX Battery?Sony VAIO VPCEB1HGX/BI Battery

Analysis of the data in conjunction with theory have assigned this activity to a meta stable state, ^257mDb. The ground state decays by alpha emission with energies 9.07 and 8.97 MeV. Spontaneous fission of ^257m,gDb was not confirmed in recent experiments.

Spectroscopic decay level schemes

²⁵⁷Db

This is the currently suggested decay level scheme for ²⁵⁷Db^g,m from the study performed in 2001 by Hessberger et al. at GSISony VAIO VPCEB1JFX Battery

Sony VAIO VPCEB1JFX/B Battery

Retracted isotopes

²⁵⁵Db

In 1983, scientists at Dubna carried out a series of supportive experiments in their quest for the discovery of Bohrium. In two such experiments, they claimed they had detected a ~1.5 s spontaneous fission activity from the reactions ²⁰⁷Pb(⁵¹V,xn) and ²⁰⁹Bi(⁴⁸Ti,xn). Sony VAIO VPCEB1JFX/G Battery

The activity was assigned to ²⁵⁵Db. Later research suggested that the assignment should be changed to ²⁵⁶Db. As such, the isotope ²⁵⁵Db is currently not recognised on the chart of radionuclides and further research is required to confirm this isotope.

Seaborgium is a synthetic chemical element with the symbol Sg and atomic number106. Sony VAIO VPCEB1JFX/L Battery,Sony VAIO VPCEB1JFX/P Battery

Seaborgium is a synthetic element whose most stable isotope ²⁷¹Sg has a half-life of 1.9 minutes. A new isotope²⁶⁹Sg has a potentially slightly longer half-life (ca. 2.1 min) based on the observation of a single decay.^{[citation needed]} Chemistry experiments with seaborgium have firmly placed it in group 6 as a heavier homologue to tungsten. Sony VAIO VPCEB1JFX/W Battery

Discovery

Element 106, now known as seaborgium, was first created in 1974 at the Super HILAC accelerator at the Lawrence Berkeley Laboratory by a joint Lawrence Berkeley/Lawrence Livermore collaboration led by Albert Ghiorso and E. Kenneth Hulet.^[1] Sony VAIO VPCEB1KGX Battery

They produced the new nuclide ²⁶³Sg by bombarding a target of ²⁴⁹Cf with ¹⁸O ions. This nuclide decays by ? emission with a half-life of 0.9 ± 0.2 sec.

Proposed names

The Berkeley/Livermore collaboration suggested the name seaborgium (Sg) to honor the American chemist Glenn T. Sony VAIO VPCEB1KGX/B Battery

Sony VAIO VPCEB1KGX/W Battery

Seaborgcredited as a member of the American group in recognition of his participation in the discovery of several other actinides. The name selected by the team became controversial. The IUPAC adopted unnilhexium(symbol Unh) as a temporary, systematic element name. In 1994 a committee of IUPAC recommended that element 106 be named rutherfordium and adopted a rule that no element can be named after a living person.^[2] Sony VAIO VPCEB1LFX Battery

Sony VAIO VPCEB1LFX/BI Battery

This ruling was fiercely objected to by the American Chemical Society. Critics pointed out that a precedent had been set in the naming of einsteinium during Albert Einstein's life and a survey indicated that chemists were not concerned with the fact that Seaborg was still alive. In 1997, as part of a compromise involving elements 104 to 108, the nameseaborgium for element 106 was recognized internationally.^[3] Sony VAIO VPCEB1LFX/WI Battery?Sony VAIO VPCEB1MFX Battery

Oxidation states

Seaborgium is projected to be the third member of the 6d series of transition metals and the heaviest member of group 6 in the Periodic Table, below chromium, molybdenum and tungsten. All the members of the group readily portray their group oxidation state of +6 and the state becomes more stable as the group is descended. Sony VAIO VPCEB1MFX/BI Battery

Sony VAIO VPCEB1NFX Battery

Thus seaborgium is expected to form a stable +6 state. For this group, stable +5 and +4 states are well represented for the heavier members and the +3 state is known but reducing, except for chromium(III).

Chemistry

Much seaborgium chemical behavior is predicted by extrapolation from its lighter cogeners molybdenum and tungsten. Sony VAIO VPCEB1NFX/B Battery

Sony VAIO VPCEB1NFX/L Battery

Molybdenum and tungsten readily form stable trioxides MO₃, so seaborgium should form SgO₃. The oxides MO₃ are soluble in alkali with the formation of oxyanions, so seaborgium should form a seaborgate ion, SgO₄^2?. In addition, WO₃ reacts with acid, suggesting similar amphotericity for SgO₃. Molybdenum oxide, MoO₃, also reacts with moisture to form a hydroxide MoO₂(OH)₂, so SgO₂(OH)₂is also feasible. Sony VAIO VPCEB1NFX/P Battery,Sony VAIO VPCEB1NFX/W Battery

The heavier homologues readily form the volatile, reactive hexahalides MX₆ (X=Cl,F). Only tungsten forms the unstable hexabromide, WBr₆. Therefore, the compounds SgF₆ and SgCl₆ are predicted, and "eka-tungsten character" may show itself in increased stability of the hexabromide, SgBr₆. Sony VAIO VPCEB1PFX Battery

These halides are unstable to oxygen and moisture and readily form volatile oxyhalides, MOX₄ and MO₂X₂. Therefore SgOX₄ (X=F,Cl) and SgO₂X₂ (X=F,Cl) should be possible. In aqueous solution, a variety of anionic oxyfluoro-complexes are formed with fluoride ion, examples being MOF₅^? and MO₃F₃^3?. Similar seaborgium complexes are expected. Sony VAIO VPCEB1PFX/B Battery

Gas phase chemistry

Initial experiments aiming at probing the chemistry of seaborgium focused on the gas thermochromatography of a volatile oxychloride. Seaborgium atoms were produced in the reaction ²⁴⁸Cm(²²Ne,4n)²⁶⁶Sg, thermalised, and reacted with an O₂/HCl mixture. Sony VAIO VPCEB1QGX Battery

The adsorption properties of the resulting oxychloride were measured and compared with those of molybdenum and tungsten compounds. The results indicated that seaborgium formed a volatile oxychloride akin to those of the other group 6 elements: Sony VAIO VPCEB1QGX/BI Battery

Sg + O₂ + 2 HCl ? SgO₂Cl₂ + H₂

In 2001, a team continued the study of the gas phase chemistry of seaborgium by reacting the element with O₂ in a H₂O environment. In a manner similar to the formation of the oxychloride, the results of the experiment indicated the formation of seaborgium oxide hydroxide, a reaction well known among the lighter group 6 homologues.^[4] Sony VAIO VPCEB1RGX Battery,Sony VAIO VPCEB1RGX/BI Battery

2 Sg + 3 O₂ ? 2 SgO₃

SgO₃ + H₂O ? SgO₂(OH)₂

Aqueous phase chemistry

In its aqueous chemistry, seaborgium has been shown to resemble its lighter homologues molybdenum and tungsten, forming a stable +6 oxidation state. Seaborgium was eluted from cation exchange resin using a HNO₃/HF solution, most likely as neutral SgO₂F₂ or the anionic complex ion [SgO₂F₃]^?. Sony VAIO VPCEB20 Battery?Sony VAIO VPCEC20 Battery

In contrast, in 0.1 M HNO₃, seaborgium does not elute, unlike Mo and W, indicating that the hydrolysis of [Sg(H₂O)₆]⁶⁺ only proceeds as far as the cationic complex [Sg(OH)₅(H₂O)]⁺.

History of synthesis of isotopes by cold fusion

This section deals with the synthesis of nuclei of seaborgium by so-called "cold" fusion reactions. These are processes which create compound nuclei at low excitation energy (~10-20 MeV, hence "cold"), leading to a higher probability of survival from fission. The excited nucleus then decays to the ground state via the emission of one or two neutrons only. Sony VAIO VPCEE20 Battery

Sony VAIO VPCEF20 Battery

Sony VAIO VPCF112FX/B Battery

²⁰⁸Pb(⁵⁴Cr,xn)^262-xSg (x=1,2,3)

The first attempt to synthesise seaborgium in cold fusion reactions was performed in September 1974 by a Soviet team led by G. N. Flerov at the Joint Institute for Nuclear Research at Dubna. They reported producing a 0.48 s spontaneous fission (SF) activity which they assigned to the isotope ²⁵⁹Sg. Sony VAIO VPCF115FG/B Battery,Sony VAIO VPCF116FGBI Battery

Based on later evidence it was suggested that the team most likely measured the decay of ²⁶⁰Sg and its daughter ²⁵⁶Rf. The TWG concluded that, at the time, the results were insufficiently convincing.^[5]

The Dubna team revisited this problem in 1983-1984 and were able to detect a 5 ms SF activity assigned directly to ²⁶⁰Sg.^[5] Sony VAIO VPCF117FJ/W Battery

Sony VAIO VPCF117HG/BI Battery

The team at GSI studied this reaction for the first time in 1985 using the improved method of correlation of genetic parent-daughter decays. They were able to detect²⁶¹Sg (x=1) and ²⁶⁰Sg and measured a partial 1n neutron evaporation excitation function. ^[6]

In December 2000, the reaction was studied by a team at GANIL, France and were able to detect 10 atoms of ²⁶¹Sg and 2 atoms of ²⁶⁰Sg to add to previous data on the reaction. Sony VAIO VPCF118FJ/W Battery,Sony VAIO VPCF119FC Battery

After a facility upgrade, the GSI team measured the 1n excitation function in 2003 using a metallic lead target. Of significance, in May 2003, the team successfully replaced the lead-208 target with more resistant lead(II) sulfide targets (PbS) which will allow more intense beams to be used in the future. Sony VAIO VPCF119FC/BI Battery

They were able to measure the 1n,2n and 3n excitation functions and performed the first detailed alpha-gamma spectroscopy on the isotope ²⁶¹Sg. They detected ~1600 atoms of the isotope and identified new alpha lines as well as measuring a more accurate half-life and new EC and SF branchings. Sony VAIO VPCF119FJ/BI Battery

Furthermore, they were able to detect the K X-rays from the daughter rutherfordium element for the first time. They were also able to provide improved data for ²⁶⁰Sg, including the tentative observation of an isomeric level. The study was continued in September 2005 and March 2006. Sony VAIO VPCF11AFJ Battery

The accumulated work on ²⁶¹Sg was published in 2007.^[7] Work in September 2005 also aimed to begin spectroscopic studies on ²⁶⁰Sg.

The team at the LBNL recently restudied this reaction in an effort to look at the spectroscopy of the isotope ²⁶¹Sg. Sony VAIO VPCF11AGJ Battery

They were able to detect a new isomer, ^261mSg, decaying by internal conversion into the ground state. In the same experiment, they were also able to confirm a K-isomer in the daughter ²⁵⁷Rf, namely ^257m2Rf.<sup>[8]

207</sup>Pb(⁵⁴Cr,xn)^261-xSg (x=1,2)

The team at Dubna also studied this reaction in 1974 with identical results as for their first experiments with a Pb-208 target. Sony VAIO VPCF11AHJ Battery

Sony VAIO VPCF11JFX/B Battery

The SF activities were first assigned to ²⁵⁹Sg and later to ²⁶⁰Sg and/or ²⁵⁶Rf. Further work in 1983-1984 also detected a 5 ms SF activity assigned to the parent ²⁶⁰Sg.^[5]

The GSI team studied this reaction for the first time in 1985 using the method of correlation of genetic parent-daughter decays. They were able to positively identify ²⁵⁹Sg as a product from the 2n neutron evaporation channel.^[6] Sony VAIO VPCF11M1E Battery?Sony VAIO VPCF11M1E/H Battery

The reaction was further used in March 2005 using PbS targets to begin a spectroscopic study of the even-even isotope ²⁶⁰Sg.

²⁰⁶Pb(⁵⁴Cr,xn)^260-xSg

This reaction was studied in 1974 by the team at Dubna. It was used to assist them in their assignment of the observed SF activities in reactions using Pb-207 and Pb-208 targets. Sony VAIO VPCF11MFX/B Battery

They were unable to detect any SF, indicating the formation of isotopes decaying primarily by alpha decay.<sup>[5]

208</sup>Pb(⁵²Cr,xn)^260-xSg (x=1,2)

The team at Dubna also studied this reaction in their series of cold fusion reactions performed in 1974. Once again they were unable to detect any SF activities.^[5] Sony VAIO VPCF11S1E Battery

The reaction was revisited in 2006 by the team at LBNL as part of their studies on the effect of the isospin of the projectile and hence the mass number of the compound nucleus on the yield of evaporation residues. They were able to identify ²⁵⁹Sg and ²⁵⁸Sg in their measurement of the 1n excitation function.^[9] Sony VAIO VPCF11S1E/B Battery

Sony VAIO VPCF11Z1E Battery

²⁰⁹Bi(⁵¹V,xn)^260-xSg (x=2)

The team at Dubna also studied this reaction in their series of cold fusion reactions performed in 1974. Once again they were unable to detect any SF activities.^[5]In 1994, the synthesis of seaborgium was revisited using this reaction by the GSI team, in order to study the new even-even isotope ²⁵⁸Sg. Ten atoms of ²⁵⁸Sg were detected and decayed by spontaneous fission. Sony VAIO VPCF11Z1E/BI Battery

Sony VAIO VPCF11ZHJ Battery

History of synthesis of isotopes by hot fusion

This section deals with the synthesis of nuclei of seaborgium by so-called "hot" fusion reactions. These are processes which create compound nuclei at high excitation energy (~40-50 MeV, hence "hot"), leading to a reduced probability of survival from fission and quasi-fission. The excited nucleus then decays to the ground state via the emission of 3-5 neutrons. Sony VAIO VPCF127HGBI Battery

Sony VAIO VPCF137HG/BI Battery

²³⁸U(³⁰Si,xn)^268-xSg (x=3,4,5,6)

This reaction was first studied by Japanese scientists at the Japan Atomic Energy Research Institute (JAERI) in 1998. They detected a spontaneous fission activity which they tentatively assigned to the new isotope ²⁶⁴Sg or ²⁶³Db, formed by EC of ²⁶³Sg.^[10] Sony VAIO VPC-P111KX/B Battery

In 2006, the teams at GSI and LBNL both studied this reaction using the method of correlation of genetic parent-daughter decays. The LBNL team measured an excitation function for the 4n,5n and 6n channels, whilst the GSI team were able to observe an additional 3n activity. Sony VAIO VPC-P111KX/D Battery

Sony VAIO VPC-P111KX/G Battery

Both teams were able to identify the new isotope ²⁶⁴Sg which decayed with a short lifetime by spontaneous fission.

²⁴⁸Cm(²²Ne,xn)^270-xSg (x=4?,5)

In 1993, at Dubna, Yuri Lazarev and his team announced the discovery of long-lived ²⁶⁶Sg and ²⁶⁵Sg produced in the 4n and 5n channels of this nuclear reaction following the search for seaborgium isotopes suitable for a first chemical study. Sony VAIO VPC-P111KX/P Battery?Sony VAIO VPC-P111KX/W Battery

It was announced that ²⁶⁶Sg decayed by 8.57 MeV alpha-particle emission with a projected half-life of ~20 s, lending strong support to the stabilising effect of the Z=108,N=162 closed shells.^[14] This reaction was studied further in 1997 by a team at GSI and the yield, decay mode and half-lives for ²⁶⁶Sg and ²⁶⁵Sg have been confirmed, although there are still some discrepancies. Sony VAIO VPC-P112KX/B Battery

Sony VAIO VPC-P112KX/D Battery

In the recent synthesis of²⁷⁰Hs (see hassium), ²⁶⁶Sg was found to undergo exclusively SF with a short half-life (T_SF = 360 ms). It is possible that this is the ground state, (^266gSg) and that the other activity, produced directly, belongs to a high spin K-isomer, ^266mSg, but further results are required to confirm this. Sony VAIO VPC-P112KX/G Battery

A recent re-evaluation of the decay characteristics of ²⁶⁵Sg and ²⁶⁶Sg has suggested that all decays to date in this reaction were in fact from ²⁶⁵Sg, which exists in two isomeric forms. The first, ^265aSg has a principal alpha-line at 8.85 MeV and a calculated half-life of 8.9 s, whilst ^265bSg has a decay energy of 8.70 MeV and a half-life of 16.2 s. Sony VAIO VPC-P112KX/P Battery

Both isomeric levels are populated when produced directly. Data from the decay of ²⁶⁹Hs indicates that ^265bSg is produced during the decay of²⁶⁹Hs and that ^265bSg decays into the shorter-lived ^261gRf isotope. This means that the observation of ²⁶⁶Sg as a long-lived alpha emitter is retracted and that it does indeed undergo fission in a short time. Sony VAIO VPC-P112KX/W Battery

Regardless of these assignments, the reaction has been successfully used in the recent attempts to study the chemistry of seaborgium (see below).

²⁴⁹Cf(¹⁸O,xn)^267-xSg (x=4)

The synthesis of seaborgium was first realized in 1974 by the LBNL/LLNL team.^[1] Sony VAIO VPCP113KX/B Battery

In their discovery experiment, they were able to apply the new method of correlation of genetic parent-daughter decays to identify the new isotope ²⁶³Sg. In 1975, the team at Oak Ridge were able to confirm the decay data but were unable to identify coincident X-rays in order to prove that seaborgium was produced. Sony VAIO VPC-P113KX/B Battery

In 1979, the team at Dubna studied the reaction by detection of SF activities. In comparison with data from Berkeley, they calculated a 70% SF branching for ²⁶³Sg. The original synthesis and discovery reaction was confirmed in 1994 by a different team at LBNL.^[15]

Synthesis of isotopes as decay products

Isotopes of seaborgium have also been observed in the decay of heavier elements. Observations to date are summarised in the table below: Sony VAIO VPCP113KX/D Battery

Sony VAIO VPC-P113KX/D Battery

Chronology of isotope discovery

There are 12 known isotopes of seaborgium (excluding meta-stable and K-spin isomers). The longest-lived is currently ²⁶⁹Sg which decays through alpha decay andspontaneous fission, with a half-life of around 2.1 minutes. The shortest-lived isotope is ²⁵⁸Sg which also decays through alpha decay and spontaneous fission. It has a half-life of 2.9 ms. Sony VAIO VPCP113KX/G Battery

Sony VAIO VPC-P113KX/G Battery

²⁶⁶Sg

Initial work identified an 8.63 MeV alpha-decaying activity with a half-life of ~21s and assigned to the ground state of ²⁶⁶Sg. Later work identified a nuclide decaying by 8.52 and 8.77 MeV alpha emission with a half-life of ~21s, which is unusual for an even-even nuclide. Sony VAIO VPCP113KX/P Battery

Recent work on the synthesis of ²⁷⁰Hs identified²⁶⁶Sg decaying by SF with a short 360 ms half-life. The recent work on ²⁷⁷Cn and ²⁶⁹Hs has provided new information on the decay of ²⁶⁵Sg and ²⁶¹Rf. This work suggested that the initial 8.77 MeV activity should be reassigned to ²⁶⁵Sg. Sony VAIO VPC-P113KX/P Battery

Therefore the current information suggests that the SF activity is the ground state and the 8.52 MeV activity is a high spin K-isomer. Further work is required to confirm these assignments. A recent re-evaluation of the data has suggested that the 8.52 MeV activity should be associated with ²⁶⁵Sg and that ²⁶⁶Sg only undergoes fission. Sony VAIO VPCP113KX/W Battery

²⁶⁵Sg

The recent direct synthesis of ²⁶⁵Sg resulted in four alpha-lines at 8.94,8.84,8.76 and 8.69 MeV with a half-life of 7.4 seconds. The observation of the decay of²⁶⁵Sg from the decay of ²⁷⁷Cn and ²⁶⁹Hs indicated that the 8.69 MeV line may be associated with an isomeric level with an associated half-life of ~ 20 s. Sony VAIO VPC-P113KX/W Battery

It is plausible that this level is causing confusion between assignments of ²⁶⁶Sg and ²⁶⁵Sg since both can decay to fissioning rutherfordium isotopes.

A recent re-evaluation of the data has indicated that there are indeed two isomers, one with a principal decay energy of 8.85 MeV with a half-life of 8.9 s, and a second isomer which decays with energy 8.70 MeV with a half-life of 16.2 s. Sony VAIO VPC-P114KX/B Battery,Sony VAIO VPC-P114KX/D Battery

²⁶³Sg

The discovery synthesis of ²⁶³Sg resulted in an alpha-line at 9.06 MeV.^[1] Observation of this nuclide by decay of ^271gDs, ^271mDs and ²⁶⁷Hs has confirmed an isomer decaying by 9.25 MeV alpha emission. The 9.06 MeV decay was also confirmed. The 9.06 MeV activity has been assigned to the ground state isomer with an associated half-life of 0.3 s. Sony VAIO VPC-P114KX/G Battery

Sony VAIO VPC-P114KX/P Battery

The 9.25 MeV activity has been assigned to an isomeric level decaying with a half-life of 0.9 s.

Recent work on the synthesis of ^271g,mDs was resulted in some confusing data regarding the decay of ²⁶⁷Hs. In one such decay, ²⁶⁷Hs decayed to ²⁶³Sg which decayed by alpha emission with a half-life of ~ 6 s. This activity has not yet been positively assigned to an isomer and further research is required. Sony VAIO VPC-P114KX/W Battery

Sony VAIO VPCP115JC Battery

²⁶⁹Sg

In the claimed synthesis of ²⁹³Uuo in 1999 the isotope ²⁶⁹Sg was identified as a daughter product. It decayed by 8.74 MeV alpha emission with a half-life of 22 s. The claim was retracted in 2001.^[19] This isotope was finally created in 2010. Sony VAIO VPCP115JC/B Battery

Cold fusion

The table below provides cross-sections and excitation energies for cold fusion reactions producing seaborgium isotopes directly. Data in bold represents maxima derived from excitation function measurements. + represents an observed exit channel. Sony VAIO VPCP115JC/D Battery

Hot fusion

The table below provides cross-sections and excitation energies for hot fusion reactions producing seaborgium isotopes directly. Data in bold represents maxima derived from excitation function measurements. + represents an observed exit channel. Sony VAIO VPCP115JC/G Battery,Sony VAIO VPCP115JC/P Battery,Sony VAIO VPCP115JC/W Battery,Sony VAIO VPCP115KG Battery