“Isotopes of tennessine”的意思、由来-开放百科全书

Tennessine (₁₁₇Ts) is the most-recently synthesized synthetic element, and much of the data is hypothetical. As for any synthetic element, a standard atomic weight cannot be given. Like all synthetic elements, it has no stable isotopes. The first (and so far only) isotopes to be synthesized were ²⁹³Ts and ²⁹⁴Ts in 2009. The longer-lived isotope is ²⁹⁴Ts with a half-life of 51 ms.

List of isotopes

Notes

Isotopes and nuclear properties

Nucleosynthesis

Target-projectile combinations leading to Z=117 compound nuclei

The below table contains various combinations of targets and projectiles that could be used to form compound nuclei with atomic number 117.

Hot fusion

²⁴⁹Bk (⁴⁸Ca, xn)^297−xTs (x=3,4)

Between July 2009 and February 2010, the team at the JINR (Flerov Laboratory of Nuclear Reactions) ran a 7-month-long experiment to synthesize tennessine using the reaction above.^[3]

The expected cross-section was of the order of 2 pb. The expected evaporation residues, ²⁹³Ts and ²⁹⁴Ts, were predicted to decay via relatively long decay chains as far as isotopes of dubnium or lawrencium.

The team published a scientific paper in April 2010 (first results were presented in January 2010^[5]) that six atoms of the neighbouring isotopes ²⁹⁴Ts (one atom) and ²⁹³Ts (five atoms) were detected. The heavier isotope decayed by the successive emission of six alpha particles down as far as the new isotope ²⁷⁰Db, which underwent apparent spontaneous fission. On the other hand, the lighter odd-even isotope decayed by the emission of just three alpha particles, as far as ²⁸¹Rg, which underwent spontaneous fission. The reaction was run at two different excitation energies of 35 MeV (dose 2×10¹⁹) and 39 MeV (dose 2.4×10¹⁹). Initial decay data was published as a preliminary presentation on the JINR website.^[6]

A further experiment in May 2010, aimed at studying the chemistry of the granddaughter of tennessine, nihonium, identified a further two atoms of ²⁸⁶Nh from the decay of ²⁹⁴Ts.

Chronology of isotope discovery

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.

Decay characteristics

Theoretical calculations in a quantum tunneling model with mass estimates from a macroscopic-microscopic model predict the alpha-decay half-lives of isotopes of tennessine (namely, ^289–303Ts) to be around 0.1–40 ms.^[9]^[10]^[11]

References

1. ^{{cite journal |last1=Oganessian |first1=Yu. Ts. |year=2013 |title=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 |journal=Physical Review C |volume=87 |issue=5 |pages=054621 |bibcode=2013PhRvC..87e4621O |doi=10.1103/PhysRevC.87.054621|display-authors=etal}}
2. ^{{cite journal |last1=Khuyagbaatar |first1=J. |last2=Yakushev |first2=A. |last3=Düllmann |first3=Ch. E. |title=⁴⁸Ca+²⁴⁹Bk Fusion Reaction Leading to Element Z=117: Long-Lived α-Decaying ²⁷⁰Db and Discovery of ²⁶⁶Lr |journal=Physical Review Letters |volume=112 |issue=17 |pages=172501 |year=2014 |doi=10.1103/PhysRevLett.112.172501 |display-authors=etal |pmid=24836239|bibcode=2014PhRvL.112q2501K }}
3. ^Tennessine – the 117th element at AtomInfo.ru
4. ^{{cite web |author=Roman Sagaidak |title=Experiment setting on synthesis of superheavy nuclei in fusion-evaporation reactions. Preparation to synthesis of new element with Z=117 |url=http://159.93.28.88/linkc/education/SHE_Sagaidak.pdf |accessdate=2009-07-07}}
5. ^Recommendations: 31st meeting, PAC for Nuclear Physics {{webarchive|url=https://web.archive.org/web/20100414173735/http://www.jinr.ru/img_sections/PAC/NP/31/PAK_NP_31_recom_eng.pdf |date=2010-04-14 }}
6. ^Walter Grenier: Recommendations, a PowerPoint presentation at the January 2010 meeting of the PAC for Nuclear Physics
7. ^¹²³⁴⁵⁶⁷⁸{{cite journal |arxiv=0708.0159 |doi=10.1088/0256-307X/24/9/024 |title=Possible Way to Synthesize Superheavy Element Z = 117 |year=2007 |last=Zhao-Qing |first=Feng |journal=Chinese Physics Letters |volume=24 |page=2551 |last2=Gen-Ming |first2=Jin |last3=Ming-Hui |first3=Huang |last4=Zai-Guo |first4=Gan |last5=Nan |first5=Wang |last6=Jun-Qing |first6=Li |issue=9 |bibcode = 2007ChPhL..24.2551F }}
8. ^¹{{cite journal |arxiv=0803.1117 |doi=10.1016/j.nuclphysa.2008.11.003 |title=Production of heavy and superheavy nuclei in massive fusion reactions |year=2009 |last=Feng |first=Z |journal=Nuclear Physics A |volume=816 |issue=1–4 |page=33 |last2=Jin |first2=G |last3=Li |first3=J |last4=Scheid |first4=W |bibcode=2009NuPhA.816...33F}}
9. ^{{cite journal |journal=Nuclear Physics A |volume=789 |issue=1–4 |pages=142–154 |year=2007 |title=Predictions of alpha decay half lives of heavy and superheavy elements |author=C. Samanta |author2=P. Roy Chowdhury |author3=D. N. Basu |doi=10.1016/j.nuclphysa.2007.04.001 |bibcode=2007NuPhA.789..142S |arxiv = nucl-th/0703086 }}
10. ^{{cite journal |journal=Physical Review C |volume=77 |page=044603 |year=2008|title=Search for long lived heaviest nuclei beyond the valley of stability |author=P. Roy Chowdhury |author2=C. Samanta |author3=D. N. Basu |doi=10.1103/PhysRevC.77.044603 |bibcode=2008PhRvC..77d4603C |issue=4 |arxiv = 0802.3837 }}
11. ^{{cite journal |journal=Atomic Data and Nuclear Data Tables |volume=94 |pages=781–806 |year=2008 |title=Nuclear half-lives for α -radioactivity of elements with 100 ≤ Z ≤ 130 |author=P. Roy Chowdhury |author2=C. Samanta |author3=D. N. Basu |doi=10.1016/j.adt.2008.01.003 |bibcode=2008ADNDT..94..781C |issue=6 |arxiv = 0802.4161 }}