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 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 0.65 seconds.

Main isotopes of moscovium (₁₁₅Mc)

Iso­tope Decay abun­dance half-life (t1/2) mode pro­duct ^287Mc syn 37 ms α ^283Nh ^288Mc syn 164 ms α ^284Nh ^289Mc syn 330 ms[1][2] α ^285Nh ^290Mc syn 650 ms[1][2] α ^286Nh

List of isotopes

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

Nuclide	Z	N	Isotopic mass (Da) [n 1][n 2]	Half-life	Decay mode	Daughter isotope	Spin and parity
^287Mc	115	172	287.19070(52)#	37(+44−13) ms	α	^283Nh
^288Mc	115	173	288.19274(62)#	164(+30−21) ms	α	^284Nh
^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

1. ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
2. # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
3. Not directly synthesized, created as decay product of ²⁹³Ts
4. Not directly synthesized, created as decay product of ²⁹⁴Ts

Nucleosynthesis

Chronology of isotope discovery

Isotope	Year discovered	Discovery reaction
^287Mc	2003	^243Am(^48Ca,4n)
^288Mc	2003	^243Am(^48Ca,3n)
^289Mc	2009	^249Bk(^48Ca,4n)[1]
^290Mc	2009	^249Bk(^48Ca,3n)[1]

Target-projectile combinations

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.

Target	Projectile	CN	Attempt result
^208Pb	^75As	^283Mc	Reaction yet to be attempted
^209Bi	^76Ge	^285Mc	Reaction yet to be attempted
^238U	^51V	^289Mc	Failure to date
^243Am	^48Ca	^291Mc[3][4]	Successful reaction
^241Am	^48Ca	^289Mc	Planned reaction
^243Am	^44Ca	^287Mc	Reaction yet to be attempted

Hot fusion

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.

²³⁸U(⁵¹V,xn)^289−xMc

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.[5]

²⁴³Am(⁴⁸Ca,xn)^291−xMc (x=2,3,4)

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.

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.

Projectile	Target	CN	2n	3n	4n	5n
^48Ca	^243Am	^291Mc		3.7 pb, 39.0 MeV	0.9 pb, 44.4 MeV

Decay characteristics

Theoretical calculations using a quantum-tunneling model support the experimental alpha-decay half-lives.[6]

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

Target	Projectile	CN	Channel (product)	σmax	Model	Ref
^243Am	^48Ca	^291Mc	3n (^288Mc)	3 pb	MD	[3]
^243Am	^48Ca	^291Mc	4n (^287Mc)	2 pb	MD	[3]
^243Am	^48Ca	^291Mc	3n (^288Mc)	1 pb	DNS	[4]
^242Am	^48Ca	^290Mc	3n (^287Mc)	2.5 pb	DNS	[4]
^241Am	^48Ca	^289Mc	4n (^285Mc)	1.04 pb	DNS	[7]

References

1. Oganessian, Yuri Ts.; Abdullin, F. Sh.; Bailey, P. D.; et al. (2010-04-09). "Synthesis of a New Element with Atomic Number Z=117". Physical Review Letters. American Physical Society. 104 (142502): 142502. Bibcode:2010PhRvL.104n2502O. doi:10.1103/PhysRevLett.104.142502. PMID 20481935.
2. Oganessian, Y.T. (2015). "Super-heavy element research". Reports on Progress in Physics. 78 (3): 036301. Bibcode:2015RPPh...78c6301O. doi:10.1088/0034-4885/78/3/036301. PMID 25746203.
3. Zagrebaev, V. (2004). "Fusion-fission dynamics of super-heavy element formation and decay" (PDF). Nuclear Physics A. 734: 164–167. Bibcode:2004NuPhA.734..164Z. doi:10.1016/j.nuclphysa.2004.01.025.
4. Feng, Z; Jin, G; Li, J; Scheid, W (2009). "Production of heavy and superheavy nuclei in massive fusion reactions". Nuclear Physics A. 816: 33–51. arXiv:0803.1117. Bibcode:2009NuPhA.816...33F. doi:10.1016/j.nuclphysa.2008.11.003.
5. "List of experiments 2000–2006". Univerzita Komenského v Bratislave. Archived from the original on July 23, 2007.
6. C. Samanta; P. Roy Chowdhury; D. N. Basu (2007). "Predictions of alpha decay half lives of heavy and superheavy elements". Nucl. Phys. A. 789: 142–154. arXiv:nucl-th/0703086. Bibcode:2007NuPhA.789..142S. doi:10.1016/j.nuclphysa.2007.04.001.
7. Zhu, L.; Su, J.; Zhang, F. (2016). "Influence of the neutron numbers of projectile and target on the evaporation residue cross sections in hot fusion reactions". Physical Review C. 93 (6). doi:10.1103/PhysRevC.93.064610.

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• Isotopic compositions and standard atomic masses from:
  • de Laeter, John Robert; Böhlke, John Karl; De Bièvre, Paul; Hidaka, Hiroshi; Peiser, H. Steffen; Rosman, Kevin J. R.; Taylor, Philip D. P. (2003). "Atomic weights of the elements. Review 2000 (IUPAC Technical Report)". Pure and Applied Chemistry. 75 (6): 683–800. doi:10.1351/pac200375060683.
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• Half-life, spin, and isomer data selected from the following sources.
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