Difference between revisions of "Isotopes of fermium"
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Revision as of 15:20, 24 September 2010
Fermium is an artificial element, and has no stable or naturally occuring isotopes. The first isotope to be discovered was 255100Fm, in fallout from the first test of a hydrogen bomb, codenamed 'Ivy Mike', in 1952. 250100Fm was discovered independently in 1954.
| Symbol | Z(p) | N(n) | Mass/u | Excess energy MeV |
Binding energy/A MeV |
β−-decay energy MeV |
Spin | Half life | Decay mode, proportion |
|---|---|---|---|---|---|---|---|---|---|
| Excitation energy/MeV | |||||||||
| 242Fm | 100 | 142 | 242.073 43(43)# | 68 400(401)# | 7465(2)# | — | 0 | 0.8(2) ms | SF (? %); α (? %) |
| 243Fm | 100 | 143 | 69260(220)# | −7⁄2# | 210(60) ms | α;[Note 1] β+ (? %); SF (59%#) | |||
| 244Fm | 100 | 144 | 69010(280) | 0 | 3.3(0.5) ms | SF (≈100%); α (0.4%#) | |||
| 245Fm | 100 | 145 | 70220(280)# | +½# | 4.2(13) s | α (? %); β+ (4.2%#); SF (0.13%#) | |||
| Values marked # are estimated from systematic trends rather than experimentally measured. Spins quoted in parentheses are uncertain in value and/or parity. Sources: Except as otherwise noted, | |||||||||
Notes and references
Notes
- ↑ The α ranching ratio depends on the uncertain branching ratio of the daughter 239Cf.
References
- ↑ Wapstra, A. H.; Audi, G.; Thibault, C. The AME2003 atomic mass evaluation (I). Evaluation of input data, adjustment procedures. Nucl. Phys. A 2003, 729, 129–336. DOI: 10.1016/j.nuclphysa.2003.11.002. Wapstra, A. H.; Audi, G.; Thibault, C. The AME2003 atomic mass evaluation (II). Tables, graphs, and references. Nucl. Phys. A 2003, 729, 337–676. DOI: 10.1016/j.nuclphysa.2003.11.003. Data tables.
- ↑ Audi, G.; Bersillon, O.; Blachot, J.; Wapstra, A. H. The NUBASE evaluation of nuclear and decay properties. Nucl. Phys. A 2003, 729, 3–128. doi:10.1016/j.nuclphysa.2003.11.001, <http://amdc.in2p3.fr/nubase/Nubase2003.pdf>.
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