Darmstadtium

Lore & Background

Darmstadtium was first discovered on November 9, 1994, at the Institute for Heavy Ion Research (Gesellschaft für Schwerionenforschung, GSI) in Darmstadt, Germany, by Peter Armbruster and Gottfried Münzenberg, under the direction of Sigurd Hofmann. The team bombarded a lead-208 target with accelerated nuclei of nickel-62 in a heavy ion accelerator and detected a single atom of the isotope darmstadtium-269. Two more atoms followed on November 12 and 17.

(Yet another was originally reported to have been found on November 11, but it turned out to be based on data fabricated by Victor Ninov, and was later retracted.) In the same series of experiments, the same team also carried out the reaction using heavier nickel-64 ions. During two runs, 9 atoms of darmstadtium-271 were convincingly detected by correlation with known daughter decay properties. Prior to this, there had been failed synthesis attempts in 1986–87 at the Joint Institute for Nuclear Research in Dubna (then in the Soviet Union) and in 1990 at the GSI.

A 1995 attempt at the Lawrence Berkeley National Laboratory resulted in signs suggesting but not pointing conclusively at the discovery of a new isotope formed in the bombardment of lead-208 with nickel-64, and a similarly inconclusive 1994 attempt at the JINR showed signs of darmstadtium-273 being produced from bismuth-209 and cobalt-59. Each team proposed its own name for element 110: the American team proposed hahnium after Otto Hahn, the Russian team proposed becquerelium after Henri Becquerel, and the German team proposed darmstadtium after Darmstadt. The IUPAC/IUPAP Joint Working Party (JWP) recognised the GSI team as discoverers in their 2001 report, giving them the right to suggest a name for the element.

Reader's Guide

Darmstadtium 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. Eleven different isotopes of darmstadtium have been reported with atomic masses 267, 269–271, 273, 275–277, and 279–281, although darmstadtium-267 is unconfirmed.

Three darmstadtium isotopes, darmstadtium-270, darmstadtium-271, and darmstadtium-281, have known metastable states, although that of darmstadtium-281 is unconfirmed. Most of these decay predominantly through alpha decay, but some undergo spontaneous fission. All darmstadtium isotopes are extremely unstable and radioactive; in general, the heavier isotopes are more stable than the lighter. The most stable known darmstadtium isotope, 281Ds, is also the heaviest known darmstadtium isotope; it has a half-life of 14 seconds.

The isotope 279Ds has a half-life of 0.18 seconds, while the unconfirmed 281mDs has a half-life of 0.9 seconds. The remaining isotopes and metastable states have half-lives between 1 microsecond and 70 milliseconds. Some unknown darmstadtium isotopes may have longer half-lives, however.

Did You Know?

• Darmstadtium is predicted to be a very noble metal with a density around 26–27 g/cm³.
• The GSI team originally considered naming the element wixhausium after the suburb Wixhausen, but decided on darmstadtium.