Isotopes of roentgenium

Roentgenium (₁₁₁Rg) 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 ²⁷²Rg in 1994, which is also the only directly synthesized isotope; all others are decay products of heavier elements. There are seven known radioisotopes, having mass numbers of 272, 274, and 278–282. The longest-lived isotope is ²⁸²Rg with a half-life of about 2 minutes, although the unconfirmed ²⁸³Rg and ²⁸⁶Rg may have longer half-lives of about 5.1 minutes and 10.7 minutes respectively.

Isotopes of roentgenium (₁₁₁Rg)

Main isotopes[1] Decay abun­dance half-life (t1/2) mode pro­duct 279Rg synth 0.09 s[2] α87% 275Mt SF13% – 280Rg synth 3.9 s α 276Mt 281Rg synth 11 s[3] SF86% – α14% 277Mt 282Rg synth 130 s α 278Mt 283Rg synth 5.1 min?[4] SF – 286Rg synth 10.7 min?[5] α 282Mt

view talk edit

List of isotopes

Nuclide	Z	N	Isotopic mass (Da) [n 1][n 2]	Half-life[1]	Decay mode[1] [n 3]	Daughter isotope	Spin and parity[1] [n 4]
272Rg	111	161	272.15327(25)#	4.2(11) ms	α	268Mt	5+#, 6+#
274Rg[n 5]	111	163	274.15525(19)#	20(11) ms	α	270Mt
278Rg[n 6]	111	167	278.16149(38)#	4.6+5.5 −1.6 ms[6]	α	274Mt
279Rg[n 7]	111	168	279.16272(51)#	90+60 −25 ms[6]	α (87%)	275Mt
					SF (13%)[6]	(various)
280Rg[n 8]	111	169	280.16514(61)#	3.9(3) s[6]	α (87%)	276Mt
					EC (13%)[7]	280Ds
281Rg[n 9]	111	170	281.16636(89)#	11+3 −1 s[6]	SF (86%)	(various)
					α (14%)[6]	277Mt[3]
282Rg[n 10]	111	171	282.16912(72)#	130(50) s	α	278Mt
283Rg[n 11]	111	172	283.17054(79)#	5.1 min?	SF	(various)
286Rg[n 12]	111	175		10.7 min?	α	282Mt
This table header & footer: view

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. Modes of decay:

   EC:	Electron capture
   SF:	Spontaneous fission

4. # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
5. Not directly synthesized, occurs as a decay product of ²⁷⁸Nh
6. Not directly synthesized, occurs as a decay product of ²⁸²Nh
7. Not directly synthesized, occurs in decay chain of ²⁸⁷Mc
8. Not directly synthesized, occurs in decay chain of ²⁸⁸Mc
9. Not directly synthesized, occurs in decay chain of ²⁹³Ts
10. Not directly synthesized, occurs in decay chain of ²⁹⁴Ts
11. Not directly synthesized, occurs in decay chain of ²⁸⁷Fl; unconfirmed
12. Not directly synthesised, occurs in decay chain of ²⁹⁰Fl and ²⁹⁴Lv; unconfirmed

Isotopes and nuclear properties

Nucleosynthesis

Super-heavy elements such as roentgenium are produced by bombarding lighter elements in particle accelerators that induce fusion reactions. Whereas the lightest isotope of roentgenium, roentgenium-272, can be synthesized directly this way, all the heavier roentgenium isotopes have only been observed as decay products of elements with higher atomic numbers.^[8]

Depending on the energies involved, fusion reactions can be categorized as "hot" or "cold". In hot fusion reactions, very light, high-energy projectiles are accelerated toward very heavy targets (actinides), giving rise to compound nuclei at high excitation energy (~40–50 MeV) that may either fission or evaporate several (3 to 5) neutrons.^[9] In cold fusion reactions, the produced fused nuclei have a relatively low excitation energy (~10–20 MeV), which decreases the probability that these products will undergo fission reactions. As the fused nuclei cool to the ground state, they require emission of only one or two neutrons, and thus, allows for the generation of more neutron-rich products.^[8] The latter is a distinct concept from that of where nuclear fusion claimed to be achieved at room temperature conditions (see cold fusion).^[10]

The table below contains various combinations of targets and projectiles which could be used to form compound nuclei with Z=111.

Target	Projectile	CN	Attempt result
205Tl	70Zn	275Rg	Failure to date
208Pb	65Cu	273Rg	Successful reaction
209Bi	64Ni	273Rg	Successful reaction
231Pa	48Ca	279Rg	Reaction yet to be attempted
238U	41K	279Rg	Reaction yet to be attempted
244Pu	37Cl	281Rg	Reaction yet to be attempted
248Cm	31P	279Rg	Reaction yet to be attempted
250Cm	31P	281Rg	Reaction yet to be attempted

Cold fusion

Before the first successful synthesis of roentgenium in 1994 by the GSI team, a team at the Joint Institute for Nuclear Research in Dubna, Russia, also tried to synthesize roentgenium by bombarding bismuth-209 with nickel-64 in 1986. No roentgenium atoms were identified. After an upgrade of their facilities, the team at GSI successfully detected 3 atoms of ²⁷²Rg in their discovery experiment.^[11] A further 3 atoms were synthesized in 2002.^[12] The discovery of roentgenium was confirmed in 2003 when a team at RIKEN measured the decays of 14 atoms of ²⁷²Rg.^[13]

The same roentgenium isotope was also observed by an American team at the Lawrence Berkeley National Laboratory (LBNL) from the reaction:

²⁰⁸
₈₂Pb
+ ⁶⁵
₂₉Cu
→ ²⁷²
₁₁₁Rg
+
n

This reaction was conducted as part of their study of projectiles with odd atomic number in cold fusion reactions.^[14]

The ²⁰⁵Tl(⁷⁰Zn,n)²⁷⁴Rg reaction was tried by the RIKEN team in 2004 and repeated in 2010 in an attempt to secure the discovery of its parent ²⁷⁸Nh:^[15]

²⁰⁵
₈₁Tl
+ ⁷⁰
₃₀Zn
→ ²⁷⁴
₁₁₁Rg
+
n

Due to the weakness of the thallium target, they were unable to detect any atoms of ²⁷⁴Rg.^[15]

As decay product

List of roentgenium isotopes observed by decay

Evaporation residue	Observed roentgenium isotope
294Lv, 290Fl, 290Nh ?	286Rg ?[5]
287Fl, 287Nh ?	283Rg ?[4]
294Ts, 290Mc, 286Nh	282Rg[16]
293Ts, 289Mc, 285Nh	281Rg[16]
288Mc, 284Nh	280Rg[17]
287Mc, 283Nh	279Rg[17]
286Mc, 282Nh	278Rg[17]
278Nh	274Rg[18]

All the isotopes of roentgenium except roentgenium-272 have been detected only in the decay chains of elements with a higher atomic number, such as nihonium. Nihonium currently has six known isotopes, with two more unconfirmed; all of them undergo alpha decays to become roentgenium nuclei, with mass numbers between 274 and 286. Parent nihonium nuclei can be themselves decay products of moscovium and tennessine, and (via unconfirmed branches) flerovium and livermorium.^[19] For example, in January 2010, the Dubna team (JINR) identified roentgenium-281 as a final product in the decay of tennessine via an alpha decay sequence:^[16]

²⁹³
₁₁₇Ts
→ ²⁸⁹
₁₁₅Mc
+ ⁴
₂He

²⁸⁹
₁₁₅Mc
→ ²⁸⁵
₁₁₃Nh
+ ⁴
₂He

²⁸⁵
₁₁₃Nh
→ ²⁸¹
₁₁₁Rg
+ ⁴
₂He

Nuclear isomerism

²⁷⁴Rg

Two atoms of ²⁷⁴Rg have been observed in the decay chain of ²⁷⁸Nh. They decay by alpha emission, emitting alpha particles with different energies, and have different lifetimes. In addition, the two entire decay chains appear to be different. This suggests the presence of two nuclear isomers but further research is required.^{[18][failed verification]}

²⁷²Rg

Four alpha particles emitted from ²⁷²Rg with energies of 11.37, 11.03, 10.82, and 10.40 MeV have been detected. The GSI measured ²⁷²Rg to have a half-life of 1.6 ms while recent data from RIKEN have given a half-life of 3.8 ms. The conflicting data may be due to nuclear isomers but the current data are insufficient to come to any firm assignments.^[11][13]

Chemical yields of isotopes

Cold fusion

The table below provides cross-sections and excitation energies for cold fusion reactions producing roentgenium isotopes directly. Data in bold represent maxima derived from excitation function measurements. + represents an observed exit channel.

Projectile	Target	CN	1n	2n	3n
64Ni	209Bi	273Rg	3.5 pb, 12.5 MeV
65Cu	208Pb	273Rg	1.7 pb, 13.2 MeV

Theoretical calculations

Evaporation residue cross sections

The below table contains various targets-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.

DNS = Di-nuclear system; σ = cross section

Target	Projectile	CN	Channel (product)	σmax	Model	Ref
238U	41K	279Rg	4n (275Rg)	0.21 pb	DNS	[20]
244Pu	37Cl	281Rg	4n (277Rg)	0.33 pb	DNS	[20]
248Cm	31P	279Rg	4n (275Rg)	1.85 pb	DNS	[20]
250Cm	31P	281Rg	4n (277Rg)	0.41 pb	DNS	[20]

References

1. 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.
2. http://www.jinr.ru/posts/both-neutron-properties-and-new-results-at-she-factory/
3. Oganessian, Yuri Ts.; Abdullin, F. Sh.; Alexander, C.; Binder, J.; et al. (2013-05-30). "Experimental studies of the ²⁴⁹Bk + ⁴⁸Ca reaction including decay properties and excitation function for isotopes of element 117, and discovery of the new isotope ²⁷⁷Mt". Physical Review C. 87 (054621). American Physical Society. Bibcode:2013PhRvC..87e4621O. doi:10.1103/PhysRevC.87.054621.
4. Hofmann, S.; Heinz, S.; Mann, R.; et al. (2016). "Remarks on the Fission Barriers of SHN and Search for Element 120". In Peninozhkevich, Yu. E.; Sobolev, Yu. G. (eds.). Exotic Nuclei: EXON-2016 Proceedings of the International Symposium on Exotic Nuclei. Exotic Nuclei. pp. 155–164. doi:10.1142/9789813226548_0024. ISBN 9789813226555.
5. Hofmann, S.; Heinz, S.; Mann, R.; et al. (2016). "Review of even element super-heavy nuclei and search for element 120". The European Physics Journal A. 2016 (52): 180. Bibcode:2016EPJA...52..180H. doi:10.1140/epja/i2016-16180-4. S2CID 124362890.
6. 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.
7. Forsberg, U.; Rudolph, D.; Andersson, L.-L.; Di Nitto, A.; Düllmann, Ch.E.; Fahlander, C.; Gates, J.M.; Golubev, P.; Gregorich, K.E.; Gross, C.J.; Herzberg, R.-D.; Heßberger, F.P.; Khuyagbaatar, J.; Kratz, J.V.; Rykaczewski, K.; Sarmiento, L.G.; Schädel, M.; Yakushev, A.; Åberg, S.; Ackermann, D.; Block, M.; Brand, H.; Carlsson, B.G.; Cox, D.; Derkx, X.; Dobaczewski, J.; Eberhardt, K.; Even, J.; Gerl, J.; et al. (2016). "Recoil-α-fission and recoil-α–α-fission events observed in the reaction 48Ca + 243Am". Nuclear Physics A. 953: 117–138. arXiv:1502.03030. Bibcode:2016NuPhA.953..117F. doi:10.1016/j.nuclphysa.2016.04.025. S2CID 55598355.
8. Armbruster, Peter & Munzenberg, Gottfried (1989). "Creating superheavy elements". Scientific American. 34: 36–42.
9. Barber, Robert C.; Gäggeler, Heinz W.; Karol, Paul J.; Nakahara, Hiromichi; Vardaci, Emanuele; Vogt, Erich (2009). "Discovery of the element with atomic number 112 (IUPAC Technical Report)". Pure and Applied Chemistry. 81 (7): 1331. doi:10.1351/PAC-REP-08-03-05.
10. Fleischmann, Martin; Pons, Stanley (1989). "Electrochemically induced nuclear fusion of deuterium". Journal of Electroanalytical Chemistry and Interfacial Electrochemistry. 261 (2): 301–308. doi:10.1016/0022-0728(89)80006-3.
11. Hofmann, S.; Ninov, V.; Heßberger, F. P.; Armbruster, P.; Folger, H.; Münzenberg, G.; Schött, H. J.; Popeko, A. G.; et al. (1995). "The new element 111". Zeitschrift für Physik A. 350 (4): 281–282. Bibcode:1995ZPhyA.350..281H. doi:10.1007/BF01291182. S2CID 18804192.
12. Hofmann, S.; Heßberger, F. P.; Ackermann, D.; Münzenberg, G.; Antalic, S.; Cagarda, P.; Kindler, B.; Kojouharova, J.; et al. (2002). "New results on elements 111 and 112". The European Physical Journal A. 14 (2): 147–157. Bibcode:2002EPJA...14..147H. doi:10.1140/epja/i2001-10119-x. S2CID 8773326.
13. Morita, K.; Morimoto, K. K.; Kaji, D.; Goto, S.; Haba, H.; Ideguchi, E.; Kanungo, R.; Katori, K.; Koura, H.; Kudo, H.; Ohnishi, T.; Ozawa, A.; Peter, J. C.; Suda, T.; Sueki, K.; Tanihata, I.; Tokanai, F.; Xu, H.; Yeremin, A. V.; Yoneda, A.; Yoshida, A.; Zhao, Y.-L.; Zheng, T. (2004). "Status of heavy element research using GARIS at RIKEN". Nuclear Physics A. 734: 101–108. Bibcode:2004NuPhA.734..101M. doi:10.1016/j.nuclphysa.2004.01.019.
14. Folden, C. M.; Gregorich, K.; Düllmann, Ch.; Mahmud, H.; Pang, G.; Schwantes, J.; Sudowe, R.; Zielinski, P.; et al. (2004). "Development of an Odd-Z-Projectile Reaction for Heavy Element Synthesis: ²⁰⁸Pb(⁶⁴Ni,n)²⁷¹Ds and ²⁰⁸Pb(⁶⁵Cu,n)²⁷²111" (PDF). Physical Review Letters. 93 (21): 212702. Bibcode:2004PhRvL..93u2702F. doi:10.1103/PhysRevLett.93.212702. PMID 15601003.
15. Morimoto, Kouji (2016). "The discovery of element 113 at RIKEN" (PDF). www.physics.adelaide.edu.au. 26th International Nuclear Physics Conference. Retrieved 14 May 2017.
16. 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): 142502. Bibcode:2010PhRvL.104n2502O. doi:10.1103/PhysRevLett.104.142502. PMID 20481935.
17. Oganessian, Yu. Ts.; Penionzhkevich, Yu. E.; Cherepanov, E. A. (2007). "Heaviest Nuclei Produced in ⁴⁸Ca-induced Reactions (Synthesis and Decay Properties)". AIP Conference Proceedings. Vol. 912. pp. 235–246. doi:10.1063/1.2746600.
18. Morita, Kosuke; Morimoto, Kouji; Kaji, Daiya; Akiyama, Takahiro; Goto, Sin-ichi; Haba, Hiromitsu; Ideguchi, Eiji; Kanungo, Rituparna; Katori, Kenji; Koura, Hiroyuki; Kudo, Hisaaki; Ohnishi, Tetsuya; Ozawa, Akira; Suda, Toshimi; Sueki, Keisuke; Xu, HuShan; Yamaguchi, Takayuki; Yoneda, Akira; Yoshida, Atsushi; Zhao, YuLiang (2004). "Experiment on the Synthesis of Element 113 in the Reaction ²⁰⁹Bi(⁷⁰Zn,n)²⁷⁸113". Journal of the Physical Society of Japan. 73 (10): 2593–2596. Bibcode:2004JPSJ...73.2593M. doi:10.1143/JPSJ.73.2593.
19. Sonzogni, Alejandro. "Interactive Chart of Nuclides". National Nuclear Data Center: Brookhaven National Laboratory. Archived from the original on 2012-12-11. Retrieved 2008-06-06.
20. Feng, Z.; Jin, G.; Li, J. (2009). "Production of new superheavy Z=108–114 nuclei with ²³⁸U, ²⁴⁴Pu and ^248,250Cm targets". Physical Review C. 80 (5): 057601. arXiv:0912.4069. doi:10.1103/PhysRevC.80.057601. S2CID 118733755.

• Isotope masses from:
  • M. Wang; G. Audi; A. H. Wapstra; F. G. Kondev; M. MacCormick; X. Xu; et al. (2012). "The AME2012 atomic mass evaluation (II). Tables, graphs and references" (PDF). Chinese Physics C. 36 (12): 1603–2014. Bibcode:2012ChPhC..36....3M. doi:10.1088/1674-1137/36/12/003. hdl:11858/00-001M-0000-0010-23E8-5. S2CID 250839471.
  • 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
• 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.
  • Yu. Ts. Oganessian (2007). "Heaviest nuclei from ⁴⁸Ca-induced reactions". Journal of Physics G. 34 (4): R165–R242. Bibcode:2007JPhG...34R.165O. doi:10.1088/0954-3899/34/4/R01.