Isotopes of darmstadtium

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Isotopes of darmstadtium  (110Ds)
Main isotopes [1] Decay
abun­dance half-life (t1/2) mode pro­duct
279Ds synth 0.2 s α 10% 275Hs
SF 90%–
281Dssynth14 sSF94%–
α6% 277Hs

Darmstadtium (110Ds) is a synthetic element, and thus a standard atomic weight cannot be given. Like all synthetic elements, it has no stable isotopes. The first isotope to be synthesized was 269Ds in 1994. There are 11 known radioisotopes from 267Ds to 281Ds (with many gaps) and 2 or 3 known isomers. The longest-lived isotope is 281Ds with a half-life of 14 seconds. However, the unconfirmed 282Ds might have an even longer half-life of 67 seconds. [2]

Contents

List of isotopes


Nuclide
[n 1] 		Z N Isotopic mass (Da) [3]
[n 2] [n 3] 		Half-life [1]
Decay
mode [1]
[n 4] 		Daughter
isotope
Spin and
parity [1]
[n 5] [n 6]
Excitation energy
267Ds [n 7] 110157267.14373(22)#10(8) μs
[2.8+13.0
−1.3 μs]		 α 263Hs3/2+#
269Ds110159269.14475(3)230(110) μs
[170+160
−60 μs]		α265Hs
270Ds110160270.14459(4)205(48) μsα266Hs0+
270mDs1390(60) keV4.3(1.2) ms
[3.9+1.5
−0.8 ms]		α (70%)266Hs10−#
IT (30%)270Ds
271Ds [n 8] 110161271.14595(10)#144(53) msSF (75%)(various)
α (25%)267Hs
271mDs [n 8] 68(27) keV1.7(4) ms
[1.63+0.44
−0.29 ms]		α267Hs
273Ds110163273.14846(15)#240(100) μs
[190+140
−60 μs]		α269Hs
273mDs [n 7] 198(20) keV120 msα269Hs
275Ds [4] 110165275.15209(37)#430+290
−120 μs		α271Hs3/2#
276Ds [5] 110166276.15302(59)#150+100
−40 μs		 SF (57%)(various)0+
α (43%)272Hs
277Ds [n 9] 110167277.15576(42)#6(3) ms
[4.1+3.7
−1.3 ms]		α273Hs
279Ds [n 10] 110169279.15998(65)#186+21
−17 ms [6] 		SF (87%) [6] (various)
α (13%)275Hs
280Ds [n 11] 110170280.16138(80)#360+172
−16 μs [7] [8] [9] 		SF(various)0+
281Ds [n 12] [n 8] 110171281.16455(53)#14(3) sSF (90%)(various)
α (10%)277Hs
281mDs [n 13] [n 8] 80(240)# keV0.9(7) ms
[0.25+1.18
−0.11 s]		α277Hs
282Ds [n 14] 110172282.16617(32)#4.2(3.3) min
[67+320
−30 s]		α278Hs0+
This table header & footer:
  1. ↑ mDs – Excited nuclear isomer.
  2. ↑ ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
  3. ↑ # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
  4. ↑ Modes of decay:
    SF: Spontaneous fission
  5. ↑ ( ) spin value – Indicates spin with weak assignment arguments.
  6. ↑ # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
  7. 1 2 Unconfirmed isotope
  8. 1 2 3 4 Order of ground state and isomer is uncertain.
  9. ↑ Not directly synthesized, occurs in decay chain of 285Fl
  10. ↑ Not directly synthesized, occurs as decay product of 283Cn
  11. ↑ Not directly synthesized, occurs in decay chain of 288Fl
  12. ↑ Not directly synthesized, occurs in decay chain of 289Fl
  13. ↑ Not directly synthesized, occurs in decay chain of 293Lv, unconfirmed
  14. ↑ Not directly synthesized, occurs in decay chain of 290Fl, unconfirmed

Isotopes and nuclear properties

Nucleosynthesis

Superheavy elements such as darmstadtium are produced by bombarding lighter elements in particle accelerators that induce fusion reactions. Whereas most of the isotopes of darmstadtium can be synthesized directly this way, some heavier ones have only been observed as decay products of elements with higher atomic numbers. [10]

Depending on the energies involved, the former are separated into "hot" and "cold". 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. 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. [10] The latter is a distinct concept from that of where nuclear fusion claimed to be achieved at room temperature conditions (see cold fusion). [12]

The table below contains various combinations of targets and projectiles which could be used to form compound nuclei with Z = 110.

TargetProjectileCNAttempt result
208Pb62Ni270DsSuccessful reaction
207Pb64Ni271DsSuccessful reaction
208Pb64Ni272DsSuccessful reaction
209Bi59Co268DsSuccessful reaction
226Ra50Ti276DsReaction yet to be attempted
232Th44Ca276DsFailure to date
232Th48Ca280DsSuccessful reaction
233U40Ar273DsFailure to date [13]
235U40Ar275DsFailure to date [13]
238U40Ar278DsSuccessful reaction
244Pu34S278DsSuccessful reaction
244Pu36S280DsReaction yet to be attempted
248Cm30Si278DsReaction yet to be attempted
250Cm30Si280DsReaction yet to be attempted

Cold fusion

Before the first successful synthesis of darmstadtium in 1994 by the GSI team, scientists at GSI also tried to synthesize darmstadtium by bombarding lead-208 with nickel-64 in 1985. No darmstadtium atoms were identified. After an upgrade of their facilities, the team at GSI successfully detected 9 atoms of 271Ds in two runs of their discovery experiment in 1994. [14] This reaction was successfully repeated in 2000 by GSI (4 atoms), in 2000 [15] [16] and 2004 [17] by the Lawrence Berkeley National Laboratory (LBNL) (9 atoms in total) and in 2002 by RIKEN (14 atoms). [18] The GSI team studied the analogous reaction with nickel-62 instead of nickel-64 in 1994 as part of their discovery experiment. Three atoms of 269Ds were detected. [14] A fourth decay chain was measured but was subsequently retracted. [19]

In addition to the official discovery reactions, in October–November 2000, the team at GSI also studied the analogous reaction using a lead-207 target in order to synthesize the new isotope 270Ds. They succeeded in synthesising eight atoms of 270Ds, relating to a ground state isomer, 270Ds, and a high-spin metastable state, 270mDs. [20]

In 1986, a team at the Joint Institute for Nuclear Research (JINR) in Dubna, Russia, studied the reaction:

209
83Bi + 59
27Co → 267
110Ds + 1
0n

They were unable to detect any darmstadtium atoms. In 1995, the team at LBNL reported that they had succeeded in detecting a single atom of 267Ds using this reaction. However, several decays were not measured and further research is required to confirm this discovery. [21]

Hot fusion

In the late 1980s, the GSI team attempted to synthesize element 110 by bombarding a target consisting of various uranium isotopes—233U, 235U, and 238U—with accelerated argon-40 ions. No atoms were detected; [22] a limiting cross section of 21 pb was reported. [13]

In September 1994, the team at Dubna detected a single atom of 273Ds by bombarding a plutonium-244 target with accelerated sulfur-34 ions. [23]

Experiments were done in 2004 at the Flerov Laboratory of Nuclear Reactions (FLNR) in Dubna studying the fission characteristics of the compound nucleus 280Ds, produced in the reaction:

232
90Th + 48
20Ca → 280
110Ds* → fission

The result revealed how compound nuclei such as this fission predominantly by expelling magic and doubly magic nuclei such as 132Sn ( Z  = 50, N  = 82). No darmstadtium atoms were obtained. [24] A compound nucleus is a loose combination of nucleons that have not arranged themselves into nuclear shells yet. It has no internal structure and is held together only by the collision forces between the target and projectile nuclei. It is estimated that it requires around 10−14 s for the nucleons to arrange themselves into nuclear shells, at which point the compound nucleus becomes a nuclide, and this number is used by IUPAC as the minimum half-life a claimed isotope must have in order to be recognized as being discovered. [25] [26]

The 232Th+48Ca reaction was attempted again at the FLNR in 2022; it was predicted that the 48Ca-induced reaction leading to element 110 would have a lower yield than those leading to lighter or heavier elements. Seven atoms of 276Ds were reported, with lifetimes ranging between 9.3 μs and 983.1 μs; four decayed by spontaneous fission and three decayed via a two-alpha sequence to 272Hs and the spontaneously fissioning 268Sg. [5] The maximum reported cross section for the production of 276Ds was about 0.7 pb and a sensitivity limit an order of magnitude lower was reached. This reported cross section is lower than that of all reactions using 48Ca as a projectile, with the exception of 249Cf + 48Ca, and it further supports the existence of magic numbers at Z = 108, N = 162 and Z = 114, N = 184. [5] In 2023, the JINR team repeated this reaction at a higher beam energy and also found 275Ds. [27] They intend to further study the reaction to search for 274Ds. [27] The FLNR also successfully synthesised 273Ds in the 238U+40Ar reaction. [4]

As decay product

List of darmstadtium isotopes observed by decay
Evaporation residueObserved darmstadtium isotope
277Cn273Ds [28]
285Fl, 281Cn277Ds [29]
291Lv, 287Fl, 283Cn279Ds [30]
288Fl, 284Cn280Ds
288Mc, 284Nh, 280Rg ?280Ds ?
293Lv, 289Fl, 285Cn281Ds [31]
290Fl, 286Cn ?282Ds ? [2]

Darmstadtium has been observed as a decay product of copernicium. Copernicium currently has seven known isotopes, four of which have been shown to alpha decay into darmstadtium, with mass numbers 273, 277, and 279–281. To date, all of these bar 273Ds have only been produced by decay of copernicium. Parent copernicium nuclei can be themselves decay products of flerovium or livermorium. Darmstadtium may also have been produced in the electron capture decay of roentgenium nuclei which are themselves daughters of nihonium and moscovium. [26] For example, in 2004, the Dubna team (JINR) identified darmstadtium-281 as a product in the decay of livermorium via an alpha decay sequence: [31]

293
116Lv
 → 289
114Fl
 + 4
2He
289
114Fl
 → 285
112Cn
 + 4
2He
285
112Cn
 → 281
110Ds
 + 4
2He

Retracted isotopes

280Ds

The first synthesis of element 114 resulted in two atoms assigned to 288Fl, decaying to the 280Ds, which underwent spontaneous fission. The assignment was later changed to 289Fl and the darmstadtium isotope to 281Ds. Hence, 280Ds remained unknown until 2016, when it was populated by the hitherto unknown alpha decay of 284Cn (previously, that nucleus was only known to undergo spontaneous fission). The discovery of 280Ds in this decay chain was confirmed in 2021; it undergoes spontaneous fission with a half-life of 360 μs. [7]

277Ds

In the claimed synthesis of 293Og in 1999, the isotope 277Ds was identified as decaying by 10.18 MeV alpha emission with a half-life of 3.0 ms. This claim was retracted in 2001. This isotope was finally created in 2010 and its decay data supported the fabrication of previous data. [32]

273mDs

In the synthesis of 277Cn in 1996 by GSI (see copernicium), one decay chain proceeded via273Ds, which decayed by emission of a 9.73 MeV alpha particle with a lifetime of 170 ms. This would have been assigned to an isomeric level. This data could not be confirmed and thus this isotope is currently unknown or unconfirmed.

272Ds

In the first attempt to synthesize darmstadtium, a 10 ms SF activity was assigned to 272Ds in the reaction 232Th(44Ca,4n). [13] Given current understanding regarding stability, this isotope has been retracted from the table of isotopes.

Nuclear isomerism

The current partial decay level scheme for Ds proposed following the work of Hofmann et al. in 2000 at GSI 270Ds decay scheme.png
The current partial decay level scheme for Ds proposed following the work of Hofmann et al. in 2000 at GSI
281Ds

The production of 281Ds by the decay of 289Fl or 293Lv has produced two very different decay modes. The most common and readily confirmed mode is spontaneous fission with a half-life of 11 s. A much rarer and as yet unconfirmed mode is alpha decay by emission of an alpha particle with energy 8.77 MeV with an observed half-life of around 3.7 min. This decay is associated with a unique decay pathway from the parent nuclides and must be assigned to an isomeric level. The half-life suggests that it must be assigned to an isomeric state but further research is required to confirm these reports. [31] It was suggested in 2016 that this unknown activity might be due to 282Mt, the great-granddaughter of 290Fl via electron capture and two consecutive alpha decays. [2]

271Ds

Decay data from the direct synthesis of 271Ds clearly indicates the presence of two nuclear isomers. The first emits alpha particles with energies 10.74 and 10.69 MeV and has a half-life of 1.63 ms. The other only emits alpha particles with an energy of 10.71 MeV and has a half-life of 69 ms. The first has been assigned to the ground state and the latter to an isomeric level. It has been suggested that the closeness of the alpha decay energies indicates that the isomeric level may decay primarily by delayed isomeric transition to the ground state, resulting in an identical measured alpha energy and a combined half-life for the two processes. [33]

270Ds

The direct production of 270Ds has clearly identified two nuclear isomers. The ground state decays by alpha emission into the ground state of 266Hs by emitting an alpha particle with energy 11.03 MeV and has a half-life of 0.10 ms. The metastable state decays by alpha emission, emitting alpha particles with energies of 12.15, 11.15, and 10.95 MeV, and has a half-life of 6 ms. When the metastable state emits an alpha particle of energy 12.15 MeV, it decays into the ground state of 266Hs, indicating that it has 1.12 MeV of excess energy. [20]

Chemical yields of isotopes

Cold fusion

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

ProjectileTargetCN1n2n3n
62Ni208Pb270Ds3.5 pb
64Ni208Pb272Ds15 pb, 9.9 MeV

Fission of compound nuclei with Z = 110

Experiments have been performed in 2004 at the Flerov Laboratory of Nuclear Reactions in Dubna studying the fission characteristics of the compound nucleus 280Ds. The nuclear reaction used is 232Th+48Ca. The result revealed how nuclei such as this fission predominantly by expelling closed shell nuclei such as 132Sn (Z = 50, N = 82). [34]

Theoretical calculations

Decay characteristics

Theoretical calculation in a quantum tunneling model reproduces the experimental alpha decay half-live data. [35] [36] It also predicts that the isotope 294Ds would have alpha decay half-life of the order of 311 years. [37] [38]

Evaporation residue cross sections

The below table contains various targets-projectile combinations for which calculations have provided estimates for cross section yields from various neutron evaporation channels. The channel with the highest expected yield is given.

DNS = Di-nuclear system; σ = cross section

TargetProjectileCNChannel (product)σmaxModelRef
208Pb64Ni272Ds1n (271Ds)10 pbDNS [39]
232Th48Ca280Ds4n (276Ds)0.2 pbDNS [40]
230Th48Ca278Ds4n (274Ds)1 pbDNS [40]
238U40Ar278Ds4n (274Ds)2 pbDNS [40]
244Pu36S280Ds4n (276Ds)0.61 pbDNS [41]
248Cm30Si278Ds4n (274Ds)65.32 pbDNS [41]
250Cm30Si280Ds4n (276Ds)3.54 pbDNS [41]

Related Research Articles

Hassium is a synthetic chemical element; it has symbol Hs and atomic number 108. It is highly radioactive: its most stable known isotopes have half-lives of approximately ten seconds. One of its isotopes, 270Hs, has magic numbers of protons and neutrons for deformed nuclei, giving it greater stability against spontaneous fission. Hassium is a superheavy element; it has been produced in a laboratory in very small quantities by fusing heavy nuclei with lighter ones. Natural occurrences of the element have been hypothesised but never found.

Meitnerium is a synthetic chemical element; it has symbol Mt and atomic number 109. It is named after Lise Meitner and is an extremely radioactive synthetic element. The most stable known isotope, meitnerium-278, has a half-life of 4.5 seconds, although the unconfirmed meitnerium-282 may have a longer half-life of 67 seconds. The GSI Helmholtz Centre for Heavy Ion Research near Darmstadt, Germany, first created this element in 1982.

Darmstadtium is a synthetic chemical element; it has symbol Ds and atomic number 110. It is extremely radioactive: the most stable known isotope, darmstadtium-281, has a half-life of approximately 14 seconds. Darmstadtium was first created in 1994 by the GSI Helmholtz Centre for Heavy Ion Research in the city of Darmstadt, Germany, after which it was named.

Livermorium is a synthetic chemical element; it has symbol Lv and atomic number 116. It is an extremely radioactive element that has only been created in a laboratory setting and has not been observed in nature. The element is named after the Lawrence Livermore National Laboratory in the United States, which collaborated with the Joint Institute for Nuclear Research (JINR) in Dubna, Russia, to discover livermorium during experiments conducted between 2000 and 2006. The name of the laboratory refers to the city of Livermore, California, where it is located, which in turn was named after the rancher and landowner Robert Livermore. The name was adopted by IUPAC on May 30, 2012. Five isotopes of livermorium are known, with mass numbers of 288 and 290–293 inclusive; the longest-lived among them is livermorium-293 with a half-life of about 80 milliseconds. A sixth possible isotope with mass number 294 has been reported but not yet confirmed.

<span class="mw-page-title-main">Island of stability</span> Predicted set of isotopes of relatively more stable superheavy elements

In nuclear physics, the island of stability is a predicted set of isotopes of superheavy elements that may have considerably longer half-lives than known isotopes of these elements. It is predicted to appear as an "island" in the chart of nuclides, separated from known stable and long-lived primordial radionuclides. Its theoretical existence is attributed to stabilizing effects of predicted "magic numbers" of protons and neutrons in the superheavy mass region.

Unbinilium, also known as eka-radium or element 120, is a hypothetical chemical element; it has symbol Ubn and atomic number 120. Unbinilium and Ubn are the temporary systematic IUPAC name and symbol, which are used until the element is discovered, confirmed, and a permanent name is decided upon. In the periodic table of the elements, it is expected to be an s-block element, an alkaline earth metal, and the second element in the eighth period. It has attracted attention because of some predictions that it may be in the island of stability.

Copernicium is a synthetic chemical element; it has symbol Cn and atomic number 112. Its known isotopes are extremely radioactive, and have only been created in a laboratory. The most stable known isotope, copernicium-285, has a half-life of approximately 30 seconds. Copernicium was first created in 1996 by the GSI Helmholtz Centre for Heavy Ion Research near Darmstadt, Germany. It was named after the astronomer Nicolaus Copernicus on his 537th anniversary.

Flerovium is a synthetic chemical element; it has symbol Fl and atomic number 114. It is an extremely radioactive, superheavy element, named after the Flerov Laboratory of Nuclear Reactions of the Joint Institute for Nuclear Research in Dubna, Russia, where the element was discovered in 1999. The lab's name, in turn, honours Russian physicist Georgy Flyorov. IUPAC adopted the name on 30 May 2012. The name and symbol had previously been proposed for element 102 (nobelium), but was not accepted by IUPAC at that time.

Nihonium is a synthetic chemical element; it has the symbol Nh and atomic number 113. It is extremely radioactive: its most stable known isotope, nihonium-286, has a half-life of about 10 seconds. In the periodic table, nihonium is a transactinide element in the p-block. It is a member of period 7 and group 13.

Rutherfordium (104Rf) is a synthetic element and thus has no stable isotopes. A standard atomic weight cannot be given. The first isotope to be synthesized was either 259Rf in 1966 or 257Rf in 1969. There are 16 known radioisotopes from 253Rf to 270Rf and several isomers. The longest-lived isotope is 267Rf with a half-life of 48 minutes, and the longest-lived isomer is 263mRf with a half-life of 8 seconds.

Seaborgium (106Sg) is a synthetic element and so has no stable isotopes. A standard atomic weight cannot be given. The first isotope to be synthesized was 263Sg in 1974. There are thirteen known radioisotopes from 258Sg to 271Sg and five known isomers. The longest-lived isotopes are 267Sg with a half-life of 9.8 minutes and 269Sg with a half-life of 5 minutes. Due to a low number of measurements, and the consequent overlapping measurement uncertainties at the confidence level corresponding to one standard deviation, a definite assignment of the most stable isotope cannot be made.

Hassium (108Hs) is a synthetic element, and thus a standard atomic weight cannot be given. Like all synthetic elements, it has no stable isotopes. The first isotope to be synthesized was 265Hs in 1984. There are 13 known isotopes from 263Hs to 277Hs and up to six isomers. The most stable known isotope is 271Hs, with a half-life of about 46 seconds, though this assignment is not definite due to uncertainty arising from a low number of measurements. The isotopes 269Hs and 270Hs respectively have half-lives of about 12 seconds and 7.6 seconds. It is also possible that the isomer 277mHs is more stable than these, with a reported half-life 130±100 seconds, but only one event of decay of this isotope has been registered as of 2016.

Meitnerium (109Mt) is a synthetic element, and thus a standard atomic weight cannot be given. Like all synthetic elements, it has no stable isotopes. The first isotope to be synthesized was 266Mt in 1982, and this is also the only isotope directly synthesized; all other isotopes are only known as decay products of heavier elements. There are eight known isotopes, from 266Mt to 278Mt. There may also be two isomers. The longest-lived of the known isotopes is 278Mt with a half-life of 8 seconds. The unconfirmed heavier 282Mt appears to have an even longer half-life of 67 seconds.

Roentgenium (111Rg) is a synthetic element, and thus a standard atomic weight cannot be given. Like all synthetic elements, it has no stable isotopes. The first isotope to be synthesized was 272Rg in 1994, which is also the only directly synthesized isotope; all others are decay products of heavier elements. There are seven known radioisotopes, having mass numbers of 272, 274, and 278–282. The longest-lived isotope is 282Rg with a half-life of about 2 minutes, although the unconfirmed 283Rg and 286Rg may have longer half-lives of about 5.1 minutes and 10.7 minutes respectively.

Copernicium (112Cn) is a synthetic element, and thus a standard atomic weight cannot be given. Like all synthetic elements, it has no stable isotopes. The first isotope to be synthesized was 277Cn in 1996. There are 6 known radioisotopes ; the longest-lived isotope is 285Cn with a half-life of 30 seconds.

Nihonium (113Nh) is a synthetic element. Being synthetic, a standard atomic weight cannot be given and like all artificial elements, it has no stable isotopes. The first isotope to be synthesized was 284Nh as a decay product of 288Mc in 2003. The first isotope to be directly synthesized was 278Nh in 2004. There are 6 known radioisotopes from 278Nh to 286Nh, along with the unconfirmed 287Nh and 290Nh. The longest-lived isotope is 286Nh with a half-life of 9.5 seconds.

Flerovium (114Fl) is a synthetic element, and thus a standard atomic weight cannot be given. Like all synthetic elements, it has no stable isotopes. The first isotope to be synthesized was 289Fl in 1999. Flerovium has six known isotopes, along with the unconfirmed 290Fl, and possibly two nuclear isomers. The longest-lived isotope is 289Fl with a half-life of 1.9 seconds, but 290Fl may have a longer half-life of 19 seconds.

Moscovium (115Mc) is a synthetic element, and thus a standard atomic weight cannot be given. Like all synthetic elements, it has no known stable isotopes. The first isotope to be synthesized was 288Mc in 2004. There are five known radioisotopes from 286Mc to 290Mc. The longest-lived isotope is 290Mc with a half-life of 0.65 seconds.

Livermorium (116Lv) is a synthetic element, and thus a standard atomic weight cannot be given. Like all artificial elements, it has no stable isotopes. The first isotope to be synthesized was 293Lv in 2000. There are five known radioisotopes, with mass numbers 288 and 290–293, as well as a few suggestive indications of a possible heavier isotope 294Lv. The longest-lived known isotope is 293Lv with a half-life of 53 ms.

Tennessine (117Ts) is the most-recently synthesized synthetic element, and much of the data is hypothetical. As for any synthetic element, a standard atomic weight cannot be given. Like all synthetic elements, it has no stable isotopes. The first isotopes to be synthesized were 293Ts and 294Ts in 2009. The longer-lived isotope is 294Ts with a half-life of 51 ms.

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