Isotopes of ununseptium

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

Table

Notes

• Values marked # are not purely derived from experimental data, but at least partly from systematic trends.
• Uncertainties are given in concise form in parentheses after the corresponding last digits. Uncertainty values from Ame2003 denote one standard deviation. Values from IUPAC are expanded uncertainties.

Isotopes and nuclear properties

Nucleosynthesis

Target-projectile combinations leading to Z=117 compound nuclei

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

Hot fusion

²⁴⁹Bk (⁴⁸Ca, xn)^297-xUus (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 ununseptium using the reaction above.^[3] The expected cross-section was of the order of 2 pb. The expected evaporation residues, ²⁹³Uus and ²⁹⁴Uus, were predicted to decay via relatively long decay chains as far as isotopes of dubnium or lawrencium.

• 

  Calculated decay chains from the parent nuclei ²⁹³Uus and ²⁹⁴ Uus^[1]

• 

  Calculated excitation function for the production of the compound nucleus ²⁹⁷Uus from the reaction²⁴⁹Bk( ⁴⁸Ca,xn) ^[1]

1. ^ ^{a b} Roman Sagaidak. "Experiment setting on synthesis of superheavy nuclei in fusion-evaporation reactions. Preparation to synthesis of new element with Z=117". Retrieved 2009-07-07. 

The team published a scientific paper in April 2010 (first results were presented in January 2010^[4]) that six atoms of the neighbouring isotopes ²⁹⁴Uus (one atom) and ²⁹³Uus (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 2x10¹⁹) and 39 MeV (dose 2.4×10¹⁹). Initial decay data was published as a preliminary presentation on the JINR website.^[5]

A further experiment in May 2010, looking at the chemistry of one of the decay products, ununtrium, identified a further two atoms derived from ²⁹⁴Uus.

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.

DNS = Di-nuclear system; σ = cross section

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 ununseptium (namely, ^289–303Uus) to be around 0.1–40 ms.^[8][9][10]

References

External sources

• 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.". Chinese Physics C, 36 (12): 1603–2014. Bibcode:2012ChPhC..36....3M. doi:10.1088/1674-1137/36/12/003.  CS1 maint: Explicit use of et al. (link)
  • Ame2003 Atomic Mass Evaluation: G. Audi, O. Bersillon, J. Blachot, A.H. Wapstra, The Nubase evaluation of nuclear and decay properties, Nucl. Phys. A729 (2003) 3-128.
• Isotopic compositions and standard atomic masses from Atomic Weights of the Elements: Review 2000 (IUPAC Technical Report). Pure Appl. Chem., Vol. 75, No. 6, pp. 683–800, (2003).

Isotopes of the chemical elements
1 H																	2 He
3 Li	4 Be											5 B	6 C	7 N	8 O	9 F	10 Ne
11 Na	12 Mg											13 Al	14 Si	15 P	16 S	17 Cl	18 Ar
19 K	20 Ca	21 Sc	22 Ti	23 V	24 Cr	25 Mn	26 Fe	27 Co	28 Ni	29 Cu	30 Zn	31 Ga	32 Ge	33 As	34 Se	35 Br	36 Kr
37 Rb	38 Sr	39 Y	40 Zr	41 Nb	42 Mo	43 Tc	44 Ru	45 Rh	46 Pd	47 Ag	48 Cd	49 In	50 Sn	51 Sb	52 Te	53 I	54 Xe
55 Cs	56 Ba		72 Hf	73 Ta	74 W	75 Re	76 Os	77 Ir	78 Pt	79 Au	80 Hg	81 Tl	82 Pb	83 Bi	84 Po	85 At	86 Rn
87 Fr	88 Ra		104 Rf	105 Db	106 Sg	107 Bh	108 Hs	109 Mt	110 Ds	111 Rg	112 Cn	113 Uut	114 Fl	115 Uup	116 Lv	117 Uus	118 Uuo
		57 La	58 Ce	59 Pr	60 Nd	61 Pm	62 Sm	63 Eu	64 Gd	65 Tb	66 Dy	67 Ho	68 Er	69 Tm	70 Yb	71 Lu
		89 Ac	90 Th	91 Pa	92 U	93 Np	94 Pu	95 Am	96 Cm	97 Bk	98 Cf	99 Es	100 Fm	101 Md	102 No	103 Lr
Table of nuclides Categories: Isotopes Tables of nuclides Metastable isotopes Isotopes by element