Isotopes of ununtrium

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Ununtrium (Uut, element 113) is a synthetic element with atomic number 113. Being synthetic, a standard atomic mass cannot be given and like all artificial elements, it has no stable isotopes. The first isotope to be synthesized was 284Uut as a decay product of 288Uup in 2003. The first isotope to be directly synthesized was 278Uut in 2004. There are 6 known radioisotopes from 278Uut to 286Uut. The longest-lived isotope is 286Uut with a half-life of 19.6 seconds.


Z(p) N(n)  
isotopic mass (u)
half-life decay
278Uut 113 165 278.17058(20)# 340 µs α 274Rg
282Uut 113 169 282.17567(39)# 73 ms α 278Rg
283Uut[n 1] 113 170 283.17657(52)# 100(+490−45) ms α 279Rg
284Uut[n 2] 113 171 284.17873(62)# 0.48(+58−17) s α 280Rg
285Uut[n 3] 113 172 285.17973(89)# 5.5 s[1] α 281Rg
286Uut[n 4] 113 173 286.18221(72)# 19.6 s[1] α 282Rg
  1. ^ Not directly synthesized, occurs as decay product of 287Uup
  2. ^ Not directly synthesized, occurs as decay product of 288Uup
  3. ^ Not directly synthesized, occurs in decay chain of 293Uus
  4. ^ Not directly synthesized, occurs in decay chain of 294Uus


  • Values marked # are not purely derived from experimental data, but at least partly from systematic trends. Spins with weak assignment arguments are enclosed in parentheses.
  • Uncertainties are given in concise form in parentheses after the corresponding last digits. Uncertainty values denote one standard deviation, except isotopic composition and standard atomic mass from IUPAC, which use expanded uncertainties.

Isotopes and nuclear properties[edit]


Super-heavy elements such as ununtrium are produced by bombarding lighter elements in particle accelerators that induce fusion reactions. Whereas most of the isotopes of ununtrium can be synthesized directly this way, some heavier ones have only been observed as decay products of elements with higher atomic numbers.[2]

Depending on the energies involved, the former are separated into "hot" and "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.[3] 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.[2] The latter is a distinct concept from that of where nuclear fusion claimed to be achieved at room temperature conditions (see cold fusion).[4]

Cold fusion[edit]

Before the successful synthesis of ununtrium by the RIKEN team, scientists at the Institute for Heavy Ion Research (Gesellschaft für Schwerionenforschung) in Darmstadt, Germany also tried to synthesize ununtrium by bombarding bismuth-209 with zinc-70 in 1998. No ununtrium atoms were identified in two separate runs of the reaction.[5] They repeated the experiment in 2003 again without success.[5] In late 2003, the emerging team at RIKEN using their efficient apparatus GARIS attempted the reaction and reached a limit of 140 fb. In December 2003 – August 2004, they resorted to "brute force" and carried out the reaction for a period of eight months. They were able to detect a single atom of 278Uut.[6] They repeated the reaction in several runs in 2005 and were able to synthesize a second atom.[7]

Hot fusion[edit]

In June 2006, the Dubna-Livermore team synthesised ununtrium directly by bombarding a neptunium-237 target with accelerated calcium-48 nuclei:

+ 48
+ 1

Two atoms of 282Uut were detected.[8]

As decay product[edit]

List of ununtrium isotopes observed by decay
Evaporation residue Observed ununtrium isotope
294Uus, 290Uup 286Uut[1]
293Uus, 289Uup 285Uut[1]
288Uup 284Uut[9]
287Uup 283Uut[9]

Ununtrium has been observed as decay products of ununpentium. Ununpentium currently has four known isotopes; all of them undergo alpha decays to become ununtrium nuclei, with mass numbers between 283 and 286. Parent ununpentium nuclei can be themselves decay products of ununseptium. To date, no other elements have been known to decay to ununtrium.[10] For example, in January 2010, the Dubna team (JINR) identified ununtrium-286 as a product in the decay of ununseptium via an alpha decay sequence:[1]

+ 4
+ 4

Theoretical calculations[edit]

Evaporation residue cross sections[edit]

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
209Bi 70Zn 279Uut 1n (278Uut) 30 fb DNS [11]
237Np 48Ca 285Uut 3n (282Uut) 0.4 pb DNS [12]


  1. ^ a b c d e Oganessian, Yu. Ts.; Abdullin, F. Sh.; Bailey, P. D.; Benker, D. E.; Bennett, M. E.; Dmitriev, S. N.; Ezold, J. G.; Hamilton, J. H.; et al. (2010). "Synthesis of a New Element with Atomic Number Z=117". Physical Review Letters 104 (14): 142502. Bibcode:2010PhRvL.104n2502O. doi:10.1103/PhysRevLett.104.142502. PMID 20481935. 
  2. ^ a b Armbruster, Peter & Münzenberg, Gottfried (1989). "Creating superheavy elements". Scientific American 34: 36–42. 
  3. ^ 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. 
  4. ^ Fleischmann, Martin; Pons, Stanley (1989). "Electrochemically induced nuclear fusion of deuterium". Journal of Electroanalytical Chemistry and Interfacial Electrochemistry (Elsevier) 261 (2): 301–308. doi:10.1016/0022-0728(89)80006-3. Retrieved 15 October 2012. 
  5. ^ a b "Search for element 113", Hofmann et al., GSI report 2003. Retrieved on 3 March 2008
  6. ^ Morita, Kosuke; Morimoto, Kouji; Kaji, Daiya; Akiyama, Takahiro; Goto, Sin-Ichi; Haba, Hiromitsu; Ideguchi, Eiji; Kanungo, Rituparna; et al. (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. 
  7. ^ Barber, Robert C.; Karol, Paul J; Nakahara, Hiromichi; Vardaci, Emanuele; Vogt, Erich W. (2011). "Discovery of the elements with atomic numbers greater than or equal to 113 (IUPAC Technical Report)". Pure and Applied Chemistry 83 (7): 1485. doi:10.1351/PAC-REP-10-05-01. 
  8. ^ Oganessian, Yu. Ts.; Utyonkov, V.; Lobanov, Yu.; Abdullin, F.; Polyakov, A.; Sagaidak, R.; Shirokovsky, I.; Tsyganov, Yu.; Voinov, A.; Gulbekian, Gulbekian; et al. (2007). "Synthesis of the isotope 282113 in the 237Np+48Ca fusion reaction" (PDF). Physical Review C 76: 011601(R). Bibcode:2007PhRvC..76a1601O. doi:10.1103/PhysRevC.76.011601. 
  9. ^ a b Oganessian, Yu. Ts.; Penionzhkevich, Yu. E.; Cherepanov, E. A. (2007). "AIP Conference Proceedings" 912: 235. doi:10.1063/1.2746600.  |chapter= ignored (help)
  10. ^ Sonzogni, Alejandro. "Interactive Chart of Nuclides". National Nuclear Data Center: Brookhaven National Laboratory. Retrieved 2008-06-06. 
  11. ^ Feng, Zhao-Qing; Jin, Gen-Ming; Li, Jun-Qing; Scheid, Werner (2007). "Formation of superheavy nuclei in cold fusion reactions". Physical Review C 76 (4): 044606. arXiv:0707.2588. Bibcode:2007PhRvC..76d4606F. doi:10.1103/PhysRevC.76.044606. 
  12. ^ 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. 

Isotopes of copernicium Isotopes of ununtrium Isotopes of flerovium
Table of nuclides