Difference between revisions of "Isotopes of fermium"

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{| class="wikitable" style="white-space:nowrap;" width=100%
 
{| class="wikitable" style="white-space:nowrap;" width=100%
−
! rowspan=2 | Symbol
+
! rowspan=2 colspan=2 | Symbol
 
! Z([[proton|p]])
 
! Z([[proton|p]])
 
! N([[neutron|n]])
 
! N([[neutron|n]])
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! colspan="3" | Excitation energy/MeV
 
! colspan="3" | Excitation energy/MeV
 
|-
 
|-
−
| <sup>242</sup>Fm
+
| colspan=2 | <sup>242</sup>Fm
 
| 100
 
| 100
 
| 142
 
| 142
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| —
 
| —
 
| align=center | 0
 
| align=center | 0
−
| 800 µs
+
| 0.8(2) ms
 
| SF (? %); α (? %)
 
| SF (? %); α (? %)
 
|-
 
|-
−
| colspan=10 | Values marked # are estimated from systematic trends rather than experimentally measured.<br/>Spins quoted in parentheses are uncertain in value and/or parity.<br/>''Sources'': Except as otherwise noted,  
+
| colspan=2 | <sup>243</sup>Fm
 +
| 100
 +
| 143
 +
|
 +
| 69 260(220)#
 +
|
 +
|
 +
| align=center | −{{frac|7|2}}#
 +
| 210(60) ms
 +
| α;<ref group="Note">The α ranching ratio depends on the uncertain branching ratio of the daughter <sup>239</sup>Cf.</ref> β<sup>+</sup> (? %); SF (59%#)
 +
|-
 +
| colspan=2 | <sup>244</sup>Fm
 +
| 100
 +
| 144
 +
|
 +
| 69 010(280)
 +
|
 +
|
 +
| align=center | 0
 +
| 3.3(0.5) ms
 +
| SF (≈100%); α (0.4%#)
 +
|-
 +
| colspan=2 | <sup>245</sup>Fm
 +
| 100
 +
| 145
 +
|
 +
| 70 220(280)#
 +
|
 +
|
 +
| align=center | +{{frac|2}}#
 +
| 4.2(13) s
 +
| α (? %); β<sup>+</sup> (4.2%#); SF (0.13%#)
 +
|-
 +
| colspan=2 | <sup>246</sup>Fm
 +
| 100
 +
| 146
 +
|
 +
| 70 140(40)
 +
|
 +
|
 +
| align=center | 0
 +
| 1.1(2) s
 +
| α (? %); β<sup>+</sup> (> 10%); SF (4.5–13%); β<sup>+</sup>SF (10–5%)
 +
|-
 +
| colspan=2 | <sup>247</sup>Fm
 +
| 100
 +
| 147
 +
|
 +
| 71 580(140)#
 +
|
 +
|
 +
| align=center | +{{frac|5|2}}#
 +
| 35(4) s
 +
| α (≥ 50%); β<sup>+</sup> (≤ 50%)
 +
|-
 +
| rowspan=3 |
 +
| <sup>247''m''</sup>Fm
 +
| colspan=3 align=center | non-existent
 +
|
 +
|
 +
|
 +
|
 +
| 9.2(23) s
 +
| α (≈100%); IT (? %)
 +
|-
 +
| <sup>247''p''</sup>Fm
 +
| colspan=3 align=center | 150(100)#
 +
| 71 730(170)#
 +
|
 +
|
 +
| align=center | (+{{frac|7|2}})
 +
|
 +
|
 +
|-
 +
| <sup>247''q''</sup>Fm
 +
| colspan=3 align=center | 400(150)#
 +
| 71 980(210)#
 +
|
 +
|
 +
|
 +
|
 +
|
 +
|-
 +
| colspan=11 | Values marked # are estimated from systematic trends rather than experimentally measured.<br/>Spins quoted in parentheses are uncertain in value and/or parity.<br/>''Sources'': Except as otherwise noted,  
 
:isotopic masses and associated energies are taken from the AME 2003 dataset;<ref name="AME">{{AME 2003}}</ref>
 
:isotopic masses and associated energies are taken from the AME 2003 dataset;<ref name="AME">{{AME 2003}}</ref>
 
:nuclear spins and decay properties are taken from N<small>UBASE</small> 2003.<ref name="Nubase">{{Nubase 2003}}.</ref>
 
:nuclear spins and decay properties are taken from N<small>UBASE</small> 2003.<ref name="Nubase">{{Nubase 2003}}.</ref>

Latest revision as of 16:52, 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 69 260(220)# −7⁄2# 210(60) ms α;[Note 1] β+ (? %); SF (59%#)
244Fm 100 144 69 010(280) 0 3.3(0.5) ms SF (≈100%); α (0.4%#)
245Fm 100 145 70 220(280)# +1⁄2# 4.2(13) s α (? %); β+ (4.2%#); SF (0.13%#)
246Fm 100 146 70 140(40) 0 1.1(2) s α (? %); β+ (> 10%); SF (4.5–13%); β+SF (10–5%)
247Fm 100 147 71 580(140)# +5⁄2# 35(4) s α (≥ 50%); β+ (≤ 50%)
247mFm non-existent 9.2(23) s α (≈100%); IT (? %)
247pFm 150(100)# 71 730(170)# (+7⁄2)
247qFm 400(150)# 71 980(210)#
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,
isotopic masses and associated energies are taken from the AME 2003 dataset;[1]
nuclear spins and decay properties are taken from NUBASE 2003.[2]

Notes and references

Notes

  1. ↑ The α ranching ratio depends on the uncertain branching ratio of the daughter 239Cf.

References

  1. ↑ 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.
  2. ↑ 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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