Английская Википедия:Isotopes of fermium

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Шаблон:Short description Шаблон:Infobox fermium isotopes Fermium (100Fm) is a synthetic element, and thus a standard atomic weight cannot be given. Like all artificial elements, it has no stable isotopes. The first isotope to be discovered (in fallout from nuclear testing) was 255Fm in 1952. 250Fm was independently synthesized shortly after the discovery of 255Fm. There are 20 known radioisotopes ranging in atomic mass from 241Fm to 260Fm (260Fm is unconfirmed), and 4 nuclear isomers, 247mFm, 250mFm, 251mFm, and 253mFm. The longest-lived isotope is 257Fm with a half-life of 100.5 days, and the longest-lived isomer is 247mFm with a half-life of 5.1 seconds.

List of isotopes

Шаблон:Isotopes table |- | rowspan=2|241Fm | rowspan=2 style="text-align:right" | 100 | rowspan=2 style="text-align:right" | 141 | rowspan=2|241.07421(32)# | rowspan=2|730(60) μs | SF | (various) | rowspan=2|5/2+# |- | α (<14%) | 237Cf |- | 242Fm | style="text-align:right" | 100 | style="text-align:right" | 142 | 242.07343(43)# | <4 μs[1] | SF | (various) | 0+ |- | rowspan=3|243Fm[2] | rowspan=3 style="text-align:right" | 100 | rowspan=3 style="text-align:right" | 143 | rowspan=3|243.07447(23)# | rowspan=3|231(9) ms | α (91%) | 239Cf | rowspan=3|(7/2−) |- | SF (9%) | (various) |- | β+ (<10%) | 243Es |- | rowspan=2|244Fm[1] | rowspan=2 style="text-align:right" | 100 | rowspan=2 style="text-align:right" | 144 | rowspan=2|244.07404(22)# | rowspan=2|3.12(8) ms | SF | (various) | rowspan=2|0+ |- | α (<1%) | 240Cf |- | rowspan=3|245Fm[3] | rowspan=3 style="text-align:right" | 100 | rowspan=3 style="text-align:right" | 145 | rowspan=3|245.07535(21)# | rowspan=3|5.5(7) s | α (88.5%) | 241Cf | rowspan=3|(1/2+) |- | β+ (11.5%) | 245Es |- | SF (<0.3%)[2] | (various) |- | rowspan=3|246Fm[4] | rowspan=3 style="text-align:right" | 100 | rowspan=3 style="text-align:right" | 146 | rowspan=3|246.075350(17) | rowspan=3|1.54(4) s | α (93.2%) | 242Cf | rowspan=3|0+ |- | SF (6.8%) | (various) |- | β+ (<1.3%) | 246Es |- | rowspan=2|247Fm[5] | rowspan=2 style="text-align:right" | 100 | rowspan=2 style="text-align:right" | 147 | rowspan=2|247.07695(12)# | rowspan=2|31(1) s | α (64%) | 243Cf | rowspan=2|(7/2+) |- | β+ (36%) | 247Es |- | rowspan=3 style="text-indent:1em" | 247mFm | rowspan=3 colspan="3" style="text-indent:2em" | 45(7) keV | rowspan=3| 5.1(2) s | α (88%) | 243Cf | rowspan=3|(1/2+) |- | IT (12%) | 247Fm |- | β+? | 247Es |- | rowspan=3|248Fm | rowspan=3 style="text-align:right" | 100 | rowspan=3 style="text-align:right" | 148 | rowspan=3|248.077186(9) | rowspan=3|35.1(8) s | α (93%) | 244Cf | rowspan=3|0+ |- | β+ (7%) | 248Es |- | SF (.10%) | (various) |- | rowspan=2|249Fm | rowspan=2 style="text-align:right" | 100 | rowspan=2 style="text-align:right" | 149 | rowspan=2|249.078928(7) | rowspan=2|1.6(1) min | β+ (84.4%) | 249Es | rowspan=2|(7/2+) |- | α (15.6%)[6] | 245Cf |- | rowspan=3|250Fm | rowspan=3 style="text-align:right" | 100 | rowspan=3 style="text-align:right" | 150 | rowspan=3|250.079521(9) | rowspan=3|30.4(15) min | α (90%) | 246Cf | rowspan=3|0+ |- | EC (10%) | 250Es |- | SF (6.9×10−3%) | (various) |- | style="text-indent:1em" | 250mFm | colspan="3" style="text-indent:2em" | 1199.2(10) keV | 1.92(5) s | IT | 250Fm | (8−) |- | rowspan=2|251Fm | rowspan=2 style="text-align:right" | 100 | rowspan=2 style="text-align:right" | 151 | rowspan=2|251.081540(16) | rowspan=2|5.30(8) h | β+ (98.2%) | 251Es | rowspan=2|(9/2−) |- | α (1.8%) | 247Cf |- | style="text-indent:1em" | 251mFm | colspan="3" style="text-indent:2em" | 200.09(11) keV | 21.1(16) μs | IT | 251Fm | (5/2+) |- | rowspan=2|252Fm | rowspan=2 style="text-align:right" | 100 | rowspan=2 style="text-align:right" | 152 | rowspan=2|252.082467(6) | rowspan=2|25.39(4) h | α (99.99%)Шаблон:R | 248Cf | rowspan=2|0+ |- | SF (.0023%) | (various) |- | rowspan=2|253Fm | rowspan=2 style="text-align:right" | 100 | rowspan=2 style="text-align:right" | 153 | rowspan=2|253.085185(4) | rowspan=2|3.00(12) d | EC (88%) | 253Es | rowspan=2|(1/2)+ |- | α (12%) | 249Cf |- | style="text-indent:1em" | 253mFm[7] | colspan="3" style="text-indent:2em" | ~351 keV | 0.56(6) μs | IT | 253Fm | (11/2-) |- | rowspan=2|254Fm | rowspan=2 style="text-align:right" | 100 | rowspan=2 style="text-align:right" | 154 | rowspan=2|254.0868544(30) | rowspan=2|3.240(2) h | α (99.94%) | 250Cf | rowspan=2|0+ |- | SF (.0592%) | (various) |- | rowspan=2|255Fm | rowspan=2 style="text-align:right" | 100 | rowspan=2 style="text-align:right" | 155 | rowspan=2|255.089964(5) | rowspan=2|20.07(7) h | α | 251Cf | rowspan=2|7/2+ |- | SF (2.4×10−5%) | (various) |- | rowspan=2|256Fm | rowspan=2 style="text-align:right" | 100 | rowspan=2 style="text-align:right" | 156 | rowspan=2|256.091774(8) | rowspan=2|157.6(13) min | SF (91.9%) | (various) | rowspan=2|0+ |- | α (8.1%) | 252Cf |- | rowspan=2|257Fm[n 1] | rowspan=2 style="text-align:right" | 100 | rowspan=2 style="text-align:right" | 157 | rowspan=2|257.095106(7) | rowspan=2|100.5(2) d | α (99.79%) | 253Cf | rowspan=2|(9/2+) |- | SF (.21%) | (various) |- | 258Fm | style="text-align:right" | 100 | style="text-align:right" | 158 | 258.09708(22)# | 370(14) μs | SF | (various) | 0+ |- | 259Fm | style="text-align:right" | 100 | style="text-align:right" | 159 | 259.1006(3)# | 1.5(3) s | SF | (various) | 3/2+# |- | 260Fm[n 2][n 3] | style="text-align:right" | 100 | style="text-align:right" | 160 | 260.10281(55)# | 4 ms | SF | (various) | 0+ Шаблон:Isotopes table/footer

Chronology of isotope discovery

Isotope Discovered Reaction
241Fm 2008 204Pb(40Ar,3n)
242Fm 1975 204Pb(40Ar,2n), 206Pb(40Ar,4n)
243Fm 1981 206Pb(40Ar,3n)
244Fm 1967 233U(16O,5n)
245Fm 1967 233U(16O,4n)
246Fm 1966 235U(16O,5n)
247Fm 1967 239Pu(12C,4n)
248Fm 1958 240Pu(12C,4n)
249Fm 1960 238U(16O,5n)
250Fm 1954 238U(16O,4n)
251Fm 1957 249Cf(α,2n)
252Fm 1956 249Cf(α,n)
253Fm 1957 252Cf(α,3n)
254Fm 1954 Neutron capture
255Fm 1954 Neutron capture
256Fm 1955 Neutron capture
257Fm 1964 Neutron capture
258Fm 1971 257Fm(d,p)
259Fm 1980 257Fm(t,p)
260Fm? 1992? 254Es+18O, 22Ne — transfer (EC of 260Md)

260Fm was not confirmed in 1997.

References

Шаблон:Navbox element isotopes


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