Moscovium (115Mc) 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 288Mc in 2004. There are four known radioisotopes from 287Mc to 290Mc. The longest-lived isotope is 290Mc with a half-life of 0.8 seconds.
||Z||N||Isotopic mass (u)
[n 1][n 2]
|289Mc[n 3]||115||174||289.19363(89)#||330(+120-80) ms||α||285Nh|
|290Mc[n 4]||115||175||290.19598(73)#||650(+490-200) ms||α||286Nh|
|Isotope||Year discovered||Discovery reaction|
The table below contains various combinations of targets and projectiles which could be used to form compound nuclei with Z=115. Each entry is a combination for which calculations have provided estimates for cross section yields from various neutron evaporation channels. The channel with the highest expected yield is given.
|208Pb||75As||283Mc||Reaction yet to be attempted|
|209Bi||76Ge||285Mc||Reaction yet to be attempted|
|238U||51V||289Mc||Failure to date|
|243Am||44Ca||287Mc||Reaction yet to be attempted|
Hot fusion reactions are processes that create compound nuclei at high excitation energy (~40–50 MeV, hence "hot"), leading to a reduced probability of survival from fission. The excited nucleus then decays to the ground state via the emission of 3–5 neutrons. Fusion reactions utilizing 48Ca nuclei usually produce compound nuclei with intermediate excitation energies (~30–35 MeV) and are sometimes referred to as "warm" fusion reactions. This leads, in part, to relatively high yields from these reactions.
There are strong indications that this reaction was performed in late 2004 as part of a uranium(IV) fluoride target test at the GSI. No reports have been published suggesting that no product atoms were detected, as anticipated by the team.
This reaction was first performed by the team in Dubna in July–August 2003. In two separate runs they were able to detect 3 atoms of 288Mc and a single atom of 287Mc. The reaction was studied further in June 2004 in an attempt to isolate the descendant 268Db from the 288Mc decay chain. After chemical separation of a +4/+5 fraction, 15 SF decays were measured with a lifetime consistent with 268Db. In order to prove that the decays were from dubnium-268, the team repeated the reaction in August 2005 and separated the +4 and +5 fractions and further separated the +5 fractions into tantalum-like and niobium-like ones. Five SF activities were observed, all occurring in the niobium-like fractions and none in the tantalum-like fractions, proving that the product was indeed isotopes of dubnium.
In a series of experiments between October 2010 – February 2011, scientists at the FLNR studied this reaction at a range of excitation energies. They were able to detect 21 atoms of 288Mc and one atom of 289Mc, from the 2n exit channel. This latter result was used to support the synthesis of tennessine. The 3n excitation function was completed with a maximum at ~8 pb. The data was consistent with that found in the first experiments in 2003.
The table below provides cross-sections and excitation energies for hot fusion reactions producing moscovium isotopes directly. Data in bold represent maxima derived from excitation function measurements. + represents an observed exit channel.
|48Ca||243Am||291Mc||3.7 pb, 39.0 MeV||0.9 pb, 44.4 MeV|
Theoretical calculations using a quantum-tunneling model support the experimental alpha-decay half-lives.
The table below contains various target-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.
MD = multi-dimensional; DNS = Di-nuclear system; σ = cross section
|243Am||48Ca||291Mc||3n (288Mc)||3 pb||MD|||
|243Am||48Ca||291Mc||4n (287Mc)||2 pb||MD|||
|243Am||48Ca||291Mc||3n (288Mc)||1 pb||DNS|||
|242Am||48Ca||290Mc||3n (287Mc)||2.5 pb||DNS|||
|241Am||48Ca||289Mc||4n (285Mc)||1.04 pb||DNS|||