Isotopes of moscovium

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.

List of isotopes

The isotopes undergo alpha decay into the corresponding isotope of nihonium, with half-lives increasing as neutron numbers increase.

|-id=Moscovium-286 | ²⁸⁶Mc | style="text-align:right" | 115 | style="text-align:right" | 171 | | | α | ²⁸²Nh | |-id=Moscovium-287 | ²⁸⁷Mc | style="text-align:right" | 115 | style="text-align:right" | 172 | 287.19082(48)# | | α | ²⁸³Nh | |-id=Moscovium-288 | ²⁸⁸Mc | style="text-align:right" | 115 | style="text-align:right" | 173 | 288.19288(58)# | | α | ²⁸⁴Nh | |-id=Moscovium-289 | ²⁸⁹Mc | style="text-align:right" | 115 | style="text-align:right" | 174 | 289.19397(83)# | | α | ²⁸⁵Nh | |-id=Moscovium-290 | ²⁹⁰Mc | style="text-align:right" | 115 | style="text-align:right" | 175 | 290.19624(64)# | <br />[] | α | ²⁸⁶Nh |

Nucleosynthesis

Target-projectile combinations

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

Hot fusion

Hot fusion reactions are processes that create compound nuclei at high excitation energy (~40–50&nbsp;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&nbsp;MeV) and are sometimes referred to as "warm" fusion reactions. This leads, in part, to relatively high yields from these reactions.

²³⁸U(⁵¹V,xn)^{289−x}Mc

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.

²⁴³Am(⁴⁸Ca,xn)^{291−x}Mc (x=2,3,4,5)

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&nbsp;pb. The data was consistent with that found in the first experiments in 2003.

This reaction was run again at five different energies in 2021 to test the new gas-filled separator at Dubna's SHE-factory. They detected 6 chains of ²⁸⁹Mc, 58 chains of ²⁸⁸Mc, and 2 chains of ²⁸⁷Mc. For the first time the 5n channel was observed with 2 atoms of ²⁸⁶Mc.

²⁴²Pu(⁵⁰Ti,pxn)^{291−x}Mc (x=2)

This reaction was studied by the team in Dubna in 2024. For the first time, a pxn reaction was successful with actinide targets and ⁴⁸Ca/⁵⁰Ti/⁵⁴Cr projectiles, producing one atom of the known ²⁸⁹Mc in the p2n channel (evaporating one proton and two neutrons).

Reaction yields

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.

Theoretical calculations

Decay characteristics

Theoretical calculations using a quantum-tunneling model support the experimental alpha-decay half-lives.

Evaporation residue cross sections

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

References

• Half-life, spin, and isomer data selected from the following sources.