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3 février 2012 5 03 /02 /février /2012 03:00

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, DbO43?, 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 DbF72– and DbOF52–. Sony VAIO VPCEB12FX/T Battery

Sony VAIO VPCEB14FX Battery

If eka-tantalum properties are portrayed, higher concentrations of fluoride should ultimately form DbF83– since NbF83– 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

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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.[12]

209Bi(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.[13]

207Pb(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.[18]

249Bk(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.[19]

250Cf(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.[23]

254Es(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 257Dbg,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, SgO42?. 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 MO3F33?. 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.[8]

207Pb(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.[5]

208Pb(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 (TSF = 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. ny-vaio-vpcp113kx-p-battery-27631.htm" title="Sony VAIO VPCP113KX/P laptop battery">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

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