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.
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List of isotopes
edit
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)[4] [n 1][n 2] |
Half-life[5] |
Decay mode[5] |
Daughter isotope |
Spin and parity[5] | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 286Mc[6] | 115 | 171 | 20+98 −9 ms |
α | 282Nh | ||||||||||||||
| 287Mc | 115 | 172 | 287.19082(48)# | 38+22 −10 ms[6] |
α | 283Nh | |||||||||||||
| 288Mc | 115 | 173 | 288.19288(58)# | 193+15 −13 ms[6] |
α | 284Nh | |||||||||||||
| 289Mc | 115 | 174 | 289.19397(83)# | 250+51 −35 ms[6] |
α | 285Nh | |||||||||||||
| 290Mc[n 3] | 115 | 175 | 290.19624(64)# | 650+490 −200 ms [0.84(36) s] |
α | 286Nh | |||||||||||||
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- ^ ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
- ^ # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
- ^ Not directly synthesized, created as decay product of 294Ts
Nucleosynthesis
edit| Isotope | Year discovered | Discovery reaction |
|---|---|---|
| 286Mc | 2021 | 243Am(48Ca,5n) |
| 287Mc | 2003 | 243Am(48Ca,4n) |
| 288Mc | 2003 | 243Am(48Ca,3n) |
| 289Mc | 2009 | 249Bk(48Ca,4n)[2] |
| 290Mc | 2009 | 249Bk(48Ca,3n)[2] |
Target-projectile combinations
editThe 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[7][8] | Successful reaction |
| 241Am | 48Ca | 289Mc | Planned reaction |
| 243Am | 44Ca | 287Mc | Reaction yet to be attempted |
Hot fusion
editHot 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
editThere 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.[9]
243Am(48Ca,xn)291−xMc (x=2,3,4,5)
editThis 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.
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.[10]
242Pu(50Ti,pxn)291−xMc (x=2)
editThis 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).[11]
Reaction yields
editThe 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 |
Theoretical calculations
editDecay characteristics
editTheoretical calculations using a quantum-tunneling model support the experimental alpha-decay half-lives.[12]
Evaporation residue cross sections
editThe 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 | [7] |
| 243Am | 48Ca | 291Mc | 4n (287Mc) | 2 pb | MD | [7] |
| 243Am | 48Ca | 291Mc | 3n (288Mc) | 1 pb | DNS | [8] |
| 242Am | 48Ca | 290Mc | 3n (287Mc) | 2.5 pb | DNS | [8] |
| 241Am | 48Ca | 289Mc | 4n (285Mc) | 1.04 pb | DNS | [13] |
References
edit- ^ Kovrizhnykh, N. (27 January 2022). "Update on the experiments at the SHE Factory". Flerov Laboratory of Nuclear Reactions. Retrieved 28 February 2022.
- ^ a b c d 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. 104 (142502). American Physical Society: 142502. Bibcode:2010PhRvL.104n2502O. doi:10.1103/PhysRevLett.104.142502. PMID 20481935.
- ^ a b 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. S2CID 37779526.
- ^ Wang, Meng; Huang, W.J.; Kondev, F.G.; Audi, G.; Naimi, S. (2021). "The AME 2020 atomic mass evaluation (II). Tables, graphs and references*". Chinese Physics C. 45 (3): 030003. doi:10.1088/1674-1137/abddaf.
- ^ a b c Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.
- ^ a b c d Oganessian, Yu. Ts.; Utyonkov, V. K.; Kovrizhnykh, N. D.; et al. (2022). "New isotope 286Mc produced in the 243Am+48Ca reaction". Physical Review C. 106 (64306): 064306. Bibcode:2022PhRvC.106f4306O. doi:10.1103/PhysRevC.106.064306. S2CID 254435744.
- ^ a b c 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.
- ^ a b c Feng, Z; Jin, G; Li, J; Scheid, W (2009). "Production of heavy and superheavy nuclei in massive fusion reactions". Nuclear Physics A. 816 (1–4): 33–51. arXiv:0803.1117. Bibcode:2009NuPhA.816...33F. doi:10.1016/j.nuclphysa.2008.11.003. S2CID 18647291.
- ^ "List of experiments 2000–2006". Univerzita Komenského v Bratislave. Archived from the original on July 23, 2007.
- ^ "Both neutron properties and new results at SHE Factory".
- ^ Ibadullayev, Dastan (2024). "Synthesis and study of the decay properties of isotopes of superheavy element Lv in Reactions 238U + 54Cr and 242Pu + 50Ti". jinr.ru. Joint Institute for Nuclear Research. Retrieved 2 November 2024.
- ^ C. Samanta; P. Roy Chowdhury; D. N. Basu (2007). "Predictions of alpha decay half lives of heavy and superheavy elements". Nucl. Phys. A. 789 (1–4): 142–154. arXiv:nucl-th/0703086. Bibcode:2007NuPhA.789..142S. doi:10.1016/j.nuclphysa.2007.04.001. S2CID 7496348.
- ^ 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): 064610. Bibcode:2016PhRvC..93f4610Z. doi:10.1103/PhysRevC.93.064610.
- Half-life, spin, and isomer data selected from the following sources.
- Audi, Georges; Bersillon, Olivier; Blachot, Jean; Wapstra, Aaldert Hendrik (2003), "The NUBASE evaluation of nuclear and decay properties", Nuclear Physics A, 729: 3–128, Bibcode:2003NuPhA.729....3A, doi:10.1016/j.nuclphysa.2003.11.001
- National Nuclear Data Center. "NuDat 2.x database". Brookhaven National Laboratory.
- Holden, Norman E. (2004). "11. Table of the Isotopes". In Lide, David R. (ed.). CRC Handbook of Chemistry and Physics (85th ed.). Boca Raton, Florida: CRC Press. ISBN 978-0-8493-0485-9.