Isotopes of fermium

Last updated
Isotopes of fermium  (100Fm)
Main isotopes [1] Decay
abun­dance half-life (t1/2) mode pro­duct
252Fm synth 25.39 h SF –
α 248Cf
253Fmsynth3 d ε 253Es
α 249Cf
255Fmsynth20.07 hSF–
α 251Cf
257Fmsynth100.5 dα 253Cf
SF–

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.

Contents

List of isotopes

Nuclide
[n 1] 		Z N Isotopic mass (Da)
[n 2] [n 3] 		Half-life
Decay
mode
[n 4] 		Daughter
isotope
Spin and
parity
[n 5] [n 6]
Excitation energy
241Fm100141241.07421(32)#730(60) μs SF (various)5/2+#
α (<14%)237Cf
242Fm100142242.07343(43)#<4 μs [2] SF(various)0+
243Fm [3] 100143243.07447(23)#231(9) msα (91%)239Cf(7/2−)
SF (9%)(various)
β+ (<10%)243Es
244Fm [4] 100144244.07404(22)#3.12(8) msSF(various)0+
α (<1%)240Cf
245Fm [5] 100145245.07535(21)#5.5(7) sα (88.5%)241Cf(1/2+)
β+ (11.5%)245Es
SF (<0.3%) [6] (various)
246Fm [7] 100146246.075350(17)1.54(4) sα (93.2%)242Cf0+
SF (6.8%)(various)
β+ (<1.3%)246Es
247Fm [8] 100147247.07695(12)#31(1) sα (64%)243Cf(7/2+)
β+ (36%)247Es
247mFm45(7) keV5.1(2) sα (88%)243Cf(1/2+)
IT (12%)247Fm
β+?247Es
248Fm100148248.077186(9)35.1(8) sα (93%)244Cf0+
β+ (7%)248Es
SF (.10%)(various)
249Fm100149249.078928(7)1.6(1) minβ+ (84.4%)249Es(7/2+)
α (15.6%) [9] 245Cf
250Fm100150250.079521(9)30.4(15) minα (90%)246Cf0+
EC (10%)250Es
SF (6.9×10−3%)(various)
250mFm1199.2(10) keV1.92(5) sIT250Fm(8−)
251Fm100151251.081540(16)5.30(8) hβ+ (98.2%)251Es(9/2−)
α (1.8%)247Cf
251mFm200.09(11) keV21.1(16) μsIT251Fm(5/2+)
252Fm100152252.082467(6)25.39(4) hα (99.99%)248Cf0+
SF (.0023%)(various)
253Fm100153253.085185(4)3.00(12) dEC (88%)253Es(1/2)+
α (12%)249Cf
253mFm [10] ~351 keV0.56(6) μsIT253Fm(11/2-)
254Fm100154254.0868544(30)3.240(2) hα (99.94%)250Cf0+
SF (.0592%)(various)
255Fm100155255.089964(5)20.07(7) hα251Cf7/2+
SF (2.4×10−5%)(various)
256Fm100156256.091774(8)157.6(13) minSF (91.9%)(various)0+
α (8.1%)252Cf
257Fm [n 7] 100157257.095106(7)100.5(2) dα (99.79%)253Cf(9/2+)
SF (.21%)(various)
258Fm100158258.09708(22)#370(14) μsSF(various)0+
259Fm100159259.1006(3)#1.5(3) sSF(various)3/2+#
260Fm [n 8] [n 9] 100160260.10281(55)#4 msSF(various)0+
This table header & footer:
  1. ↑ mFm – Excited nuclear isomer.
  2. ↑ ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
  3. ↑ # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
  4. ↑ Modes of decay:
    EC: Electron capture
    IT: Isomeric transition
    SF: Spontaneous fission
  5. ↑ ( ) spin value – Indicates spin with weak assignment arguments.
  6. ↑ # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
  7. ↑ Heaviest nuclide produced via neutron capture
  8. ↑ Discovery of this isotope is unconfirmed
  9. ↑ Not directly synthesized, occurs as decay product of 260Md

Chronology of isotope discovery

IsotopeDiscoveredReaction
241Fm2008204Pb(40Ar,3n)
242Fm1975204Pb(40Ar,2n), 206Pb(40Ar,4n)
243Fm1981206Pb(40Ar,3n)
244Fm1967233U(16O,5n)
245Fm1967233U(16O,4n)
246Fm1966235U(16O,5n)
247Fm1967239Pu(12C,4n)
248Fm1958240Pu(12C,4n)
249Fm1960238U(16O,5n)
250Fm1954238U(16O,4n)
251Fm1957249Cf(α,2n)
252Fm1956249Cf(α,n)
253Fm1957252Cf(α,3n)
254Fm1954Neutron capture
255Fm1954Neutron capture
256Fm1955Neutron capture
257Fm1964Neutron capture
258Fm1971257Fm(d,p)
259Fm1980257Fm(t,p)
260Fm?1992?254Es+18O, 22Ne — transfer (EC of 260Md)

260Fm was not confirmed in 1997.

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Einsteinium (99Es) is a synthetic element, and thus a standard atomic weight cannot be given. Like all synthetic elements, it has no stable isotopes. The first isotope to be discovered was 253Es in 1952. There are 18 known radioisotopes from 240Es to 257Es, and 3 nuclear isomers. The longest-lived isotope is 252Es with a half-life of 471.7 days, or around 1.293 years.

Mendelevium (101Md) 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 synthesized was 256Md in 1955. There are 17 known radioisotopes, ranging in atomic mass from 244Md to 260Md, and 5 isomers. The longest-lived isotope is 258Md with a half-life of 51.3 days, and the longest-lived isomer is 258mMd with a half-life of 57 minutes.

Nobelium (102No) is a synthetic element, and thus a standard atomic weight cannot be given. Like all synthetic elements, it has no stable isotopes. The first isotope to be synthesized was 254No in 1966. There are thirteen known radioisotopes, which are 249No to 260No and 262No, and many isomers. The longest-lived isotope is 259No with a half-life of 58 minutes. The longest-lived isomer is 251m1No with a half-life of 1.02 seconds.

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Rutherfordium (104Rf) is a synthetic element and thus has no stable isotopes. A standard atomic weight cannot be given. The first isotope to be synthesized was either 259Rf in 1966 or 257Rf in 1969. There are 16 known radioisotopes from 253Rf to 270Rf and several isomers. The longest-lived isotope is 267Rf with a half-life of 48 minutes, and the longest-lived isomer is 263mRf with a half-life of 8 seconds.

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Roentgenium (111Rg) is a synthetic element, and thus a standard atomic weight cannot be given. Like all synthetic elements, it has no stable isotopes. The first isotope to be synthesized was 272Rg in 1994, which is also the only directly synthesized isotope; all others are decay products of heavier elements. There are seven known radioisotopes, having mass numbers of 272, 274, and 278–282. The longest-lived isotope is 282Rg with a half-life of about 2 minutes, although the unconfirmed 283Rg and 286Rg may have longer half-lives of about 5.1 minutes and 10.7 minutes respectively.

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Nihonium (113Nh) is a synthetic element. Being synthetic, a standard atomic weight cannot be given and like all artificial elements, it has no stable isotopes. The first isotope to be synthesized was 284Nh as a decay product of 288Mc in 2003. The first isotope to be directly synthesized was 278Nh in 2004. There are 6 known radioisotopes from 278Nh to 286Nh, along with the unconfirmed 287Nh and 290Nh. The longest-lived isotope is 286Nh with a half-life of 9.5 seconds.

Livermorium (116Lv) is an artificial element, and thus a standard atomic weight cannot be given. Like all artificial elements, it has no stable isotopes. The first isotope to be synthesized was 293Lv in 2000. There are four known radioisotopes from 290Lv to 293Lv, as well as a few suggestive indications of a possible heavier isotope 294Lv. The longest-lived of the four well-characterised isotopes is 293Lv with a half-life of 53 ms.

References

  1. ↑ Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.
  2. ↑ Khuyagbaatar, J.; Hofmann, S.; Heßberger, F. P.; Ackermann, D.; Burkhard, H. G.; Heinz, S.; Kindler, B.; Kojouharov, I.; Lommel, B.; Mann, R.; Maurer, J.; Nishio, K.; Novikov, Yu. (1 August 2008). "Spontaneous fission of neutron-deficient fermium isotopes and the new nucleus 241Fm" (PDF). The European Physical Journal A. 37 (2): 177–183. Bibcode:2008EPJA...37..177K. doi:10.1140/epja/i2008-10608-4. ISSN   1434-601X. S2CID   18977014 . Retrieved 24 June 2023.
  3. ↑ Khuyagbaatar, J.; Heßberger, F. P.; Hofmann, S.; Ackermann, D.; Burkhard, H. G.; Heinz, S.; Kindler, B.; Kojouharov, I.; Lommel, B.; Mann, R.; Maurer, J.; Nishio, K. (12 October 2020). "α decay of Fm 243 143 and Fm 245 145 , and of their daughter nuclei". Physical Review C. 102 (4): 044312. doi:10.1103/PhysRevC.102.044312. ISSN   2469-9985. S2CID   241259726 . Retrieved 24 June 2023.
  4. ↑ Khuyagbaatar, J.; Hofmann, S.; Heßberger, F. P.; Ackermann, D.; Burkhard, H. G.; Heinz, S.; Kindler, B.; Kojouharov, I.; Lommel, B.; Mann, R.; Maurer, J.; Nishio, K.; Novikov, Yu. (1 August 2008). "Spontaneous fission of neutron-deficient fermium isotopes and the new nucleus 241Fm" (PDF). The European Physical Journal A. 37 (2): 177–183. Bibcode:2008EPJA...37..177K. doi:10.1140/epja/i2008-10608-4. ISSN   1434-601X. S2CID   18977014 . Retrieved 24 June 2023.
  5. ↑ Tezekbayeva, M. S.; Yeremin, A. V.; Svirikhin, A. I.; Lopez-Martens, A.; Chelnokov, M. L.; Chepigin, V. I.; Isaev, A. V.; Izosimov, I. N.; Karpov, A. V.; Kuznetsova, A. A.; Malyshev, O. N.; Mukhin, R. S.; Popeko, A. G.; Popov, Yu. A.; Rachkov, V. A.; Sailaubekov, B. S.; Sokol, E. A.; Hauschild, K.; Jacob, H.; Chakma, R.; Dorvaux, O.; Forge, M.; Gall, B.; Kessaci, K.; Andel, B.; Antalic, S.; Bronis, A.; Mosat, P. (24 March 2022). "Study of the production and decay properties of neutron-deficient nobelium isotopes". The European Physical Journal A. 58 (3): 52. arXiv: 2203.15659 . Bibcode:2022EPJA...58...52T. doi:10.1140/epja/s10050-022-00707-9. ISSN   1434-601X. S2CID   247720708 . Retrieved 24 June 2023.
  6. ↑ Khuyagbaatar, J.; Heßberger, F. P.; Hofmann, S.; Ackermann, D.; Burkhard, H. G.; Heinz, S.; Kindler, B.; Kojouharov, I.; Lommel, B.; Mann, R.; Maurer, J.; Nishio, K. (12 October 2020). "α decay of Fm 243 143 and Fm 245 145 , and of their daughter nuclei". Physical Review C. 102 (4): 044312. doi:10.1103/PhysRevC.102.044312. ISSN   2469-9985. S2CID   241259726 . Retrieved 24 June 2023.
  7. ↑ Venhart, M.; Heßberger, F. P.; Ackermann, D.; Antalic, S.; Gray-Jones, C.; Greenlees, P. T.; Heinz, S.; Herzberg, R. -D.; Hofmann, S.; Ketelhut, S.; Kindler, B.; Kojouharov, I.; Leino, M.; Lommel, B.; Mann, R.; Papadakis, P.; Rostron, D.; Rudolph, D.; Šáro, Š.; Sulignano, B. (4 February 2011). "Decay study of 246Fm at SHIP" (PDF). The European Physical Journal A. 47 (2): 20. Bibcode:2011EPJA...47...20V. doi:10.1140/epja/i2011-11020-9. ISSN   1434-601X. S2CID   119353521 . Retrieved 24 June 2023.
  8. ↑ Heßberger, F. P.; Hofmann, S.; Ackermann, D.; Antalic, S.; Kindler, B.; Kojouharov, I.; Kuusiniemi, P.; Leino, M.; Lommel, B.; Mann, R.; Nishio, K.; Popeko, A. G.; Sulignano, B.; Saro, S.; Streicher, B.; Venhart, M.; Yeremin, A. V. (1 December 2006). "Alpha-gamma decay studies of 255Rf, 251No and 247Fm" (PDF). The European Physical Journal A - Hadrons and Nuclei. 30 (3): 561–569. Bibcode:2006EPJA...30..561H. doi:10.1140/epja/i2006-10137-2. ISSN   1434-601X. S2CID   123871572 . Retrieved 24 June 2023.
  9. ↑ Heßberger, F. P.; Antalic, S.; Ackermann, D.; Kalaninová, Z.; Heinz, S.; Hofmann, S.; Streicher, B.; Kindler, B.; Kojouharov, I.; Kuusiniemi, P.; Leino, M.; Lommel, B.; Mann, R.; Nishio, K.; Šáro, Š.; Sulignano, B.; Venhart, M. (29 May 2012). "Alpha-gamma decay studies of 253No and its daughter products 253Md , 249Fm" (PDF). The European Physical Journal A. 48 (5): 75. Bibcode:2012EPJA...48...75H. doi:10.1140/epja/i2012-12075-8. ISSN   1434-601X. S2CID   254111959 . Retrieved 25 June 2023.
  10. ↑ Antalic, S.; Heßberger, F. P.; Ackermann, D.; Heinz, S.; Hofmann, S.; Kalaninová, Z.; Kindler, B.; Khuyagbaatar, J.; Kojouharov, I.; Kuusiniemi, P.; Leino, M.; Lommel, B.; Mann, R.; Nishio, K.; Šáro, Š.; Streicher, B.; Sulignano, B.; Venhart, M. (20 May 2011). "Isomeric states in 253No and 253Fm" (PDF). The European Physical Journal A. 47 (5): 62. Bibcode:2011EPJA...47...62A. doi:10.1140/epja/i2011-11062-y. ISSN   1434-601X. S2CID   121080273 . Retrieved 25 June 2023.
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