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.
List of isotopes
|-id=Darmstadtium-267 | 267DsDiscovery of this isotope is unconfirmed | style="text-align:right" | 110 | style="text-align:right" | 157 | 267.14373(22)# | style="text-align:center" | 1995 | [] | α | 263Hs | 3/2+# |-id=Darmstadtium-269 | 269Ds | style="text-align:right" | 110 | style="text-align:right" | 159 | 269.14475(3) | style="text-align:center" | 1995 | [] | α | 265Hs | |-id=Darmstadtium-270 | 270Ds | style="text-align:right" | 110 | style="text-align:right" | 160 | 270.14459(4) | style="text-align:center" | 2001 | | α | 266Hs | 0+ |-id=Darmstadtium-270m | rowspan=2 style="text-indent:1em" | 270mDs | rowspan=2 colspan="3" style="text-indent:2em" | 1390(60) keV | rowspan=2 style="text-align:center" | 2001 | rowspan=2|[] | α (70%) | 266Hs | rowspan=2|10−# |- | IT (30%) | 270Ds |-id=Darmstadtium-271 | rowspan=2|271Ds | rowspan=2 style="text-align:right" | 110 | rowspan=2 style="text-align:right" | 161 | rowspan=2|271.14595(10)# | rowspan=2 style="text-align:center" | 1995 | rowspan=2|144(53) ms |SF (75%) |(various) |rowspan=2| |- | α (25%) | 267Hs |-id=Darmstadtium-271m | style="text-indent:1em" | 271mDsOrder of ground state and isomer is uncertain. | colspan="3" style="text-indent:2em" | 68(27) keV | style="text-align:center" | 1998 | [] | α | 267Hs | |-id=Darmstadtium-272 | rowspan=2 | 272Ds | rowspan=2 style="text-align:right" | 110 | rowspan=2 style="text-align:right" | 162 | rowspan=2 | 272.146091(456)# | rowspan=2 style="text-align:center" | (1989) | rowspan=2 | 200# ms | SF? |(various) |- | α? | 268Hs |-id=Darmstadtium-273 | 273Ds | style="text-align:right" | 110 | style="text-align:right" | 163 | 273.14846(15)# | style="text-align:center" | 1996 | [] | α | 269Hs | |-id=Darmstadtium-273m | style="text-indent:1em" | 273mDsDiscovery of this isomer is unconfirmed | colspan="3" style="text-indent:2em" | 198(20) keV | style="text-align:center" | 2024 | 120 ms | α | 269Hs | |-id=Darmstadtium-275 |275Ds | style="text-align:right" | 110 | style="text-align:right" | 165 |275.15209(37)# | style="text-align:center" | 2024 | |α |271Hs | 3/2# |-id=Darmstadtium-276 | rowspan=2|276Ds | rowspan=2 style="text-align:right" | 110 | rowspan=2 style="text-align:right" | 166 | rowspan=2|276.15302(59)# | rowspan=2 style="text-align:center" | 2023 | rowspan=2| | SF (57%) | (various) | rowspan=2|0+ |- | α (43%) | 272Hs |-id=Darmstadtium-277 | 277DsNot directly synthesized, occurs in decay chain of 285Fl | style="text-align:right" | 110 | style="text-align:right" | 167 | 277.15576(42)# | style="text-align:center" | 2010 | | α | 273Hs | |-id=Darmstadtium-279 | rowspan=2|279DsNot directly synthesized, occurs as decay product of 283Cn | rowspan=2 style="text-align:right" | 110 | rowspan=2 style="text-align:right" | 169 | rowspan=2|279.15998(65)# | rowspan=2 style="text-align:center" | 2004 | rowspan=2| | SF (87%) | (various) | rowspan=2| |- | α (13%) | 275Hs |-id=Darmstadtium-280 | 280DsNot directly synthesized, occurs in decay chain of 288Fl | style="text-align:right" | 110 | style="text-align:right" | 170 | 280.16138(80)# | style="text-align:center" | 2021 | | SF | (various) | 0+ |-id=Darmstadtium-281 | rowspan=2|281DsNot directly synthesized, occurs in decay chain of 289Fl | rowspan=2 style="text-align:right" | 110 | rowspan=2 style="text-align:right" | 171 | rowspan=2|281.16455(53)# | rowspan=2 style="text-align:center" | 2004 | rowspan=2| | SF (90%) | (various) | rowspan=2| |- | α (10%) | 277Hs |-id=Darmstadtium-281m | style="text-indent:1em" | 281mDsNot directly synthesized, occurs in decay chain of 293Lv, unconfirmed | colspan="3" style="text-indent:2em" | 80(240)# keV | style="text-align:center" | 2012 | [] | α | 277Hs | |-id=Darmstadtium-282 | 282DsNot directly synthesized, occurs in decay chain of 290Fl, unconfirmed |style="text-align:right" | 110 |style="text-align:right" | 172 |282.16617(32)# | style="text-align:center" | (2016) | [] | α | 278Hs |0+
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.
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. 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. The latter is a distinct concept from that of where nuclear fusion claimed to be achieved at room temperature conditions (see cold fusion).
The table below contains various combinations of targets and projectiles which could be used to form compound nuclei with Z = 110.
Target Projectile CN Attempt result208Pb62Ni270Ds207Pb64Ni271Ds208Pb64Ni272Ds209Bi59Co268Ds226Ra50Ti276Ds232Th44Ca276Ds232Th48Ca280Ds233U40Ar273Ds235U40Ar275Ds238U40Ar278Ds244Pu34S278Ds244Pu36S280Ds248Cm30Si278Ds250Cm30Si280Ds
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. This reaction was successfully repeated in 2000 by GSI (4 atoms), in 2000 (preprint) and 2004 by the Lawrence Berkeley National Laboratory (LBNL) (9 atoms in total) and in 2002 by RIKEN (14 atoms). 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. A fourth decay chain was measured but was subsequently retracted.
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.
In 1986, a team at the Joint Institute for Nuclear Research (JINR) in Dubna, Russia, studied the reaction:
Bi + Co → Ds + n
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.
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; a limiting cross section of 21 pb was reported.
In September 1994, the team at Dubna detected a single atom of 273Ds by bombarding a plutonium-244 target with accelerated sulfur-34 ions.
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:
Th + Ca → Ds* → 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.Flerov lab annual report 2004 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.
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 and ; four decayed by spontaneous fission and three decayed via a two-alpha sequence to 272Hs and the spontaneously fissioning 268Sg. 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. In 2023, the JINR team repeated this reaction at a higher beam energy and also found 275Ds. They intend to further study the reaction to search for 274Ds. The FLNR also successfully synthesised 273Ds in the 238U+40Ar reaction.
As decay product +List of darmstadtium isotopes observed by decay Evaporation residue Observed darmstadtium isotope277Cn 273Ds285Fl, 281Cn277Ds291Lv, 287Fl, 283Cn279Ds288Fl, 284Cn280Ds288Mc, 284Nh, 280Rg ? 280Ds ?293Lv, 289Fl, 285Cn281Ds290Fl, 286Cn ? 282Ds ? Darmstadtium has been observed as a decay product of copernicium. Copernicium currently has seven known isotopes, five 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. For example, in 2004, the Dubna team (JINR) identified darmstadtium-281 as a product in the decay of livermorium via an alpha decay sequence:
→ + → + → +
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.
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.see Oganesson
273mDs