Physics:Isotopes of einsteinium

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Short description: Nuclides with atomic number of 99 but with different mass numbers
Main isotopes of Chemistry:einsteinium (99Es)
Iso­tope Decay
abun­dance half-life (t1/2) mode pro­duct
252Es syn 471.7 d α 248Bk
ε 252Cf
β 252Fm
253Es syn 20.47 d SF
α 249Bk
254Es syn 275.7 d ε 254Cf
β 254Fm
α 250Bk
255Es syn 39.8 d β 255Fm
α 251Bk
SF
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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 (in nuclear fallout from the Ivy Mike H-bomb test) was 253Es in 1952. There are 18 known radioisotopes from 240Es to 257Es, and 3 nuclear isomers (250mEs, 254mEs, and 256mEs). The longest-lived isotope is 252Es with a half-life of 471.7 days, or around 1.293 years.

List of isotopes

Nuclide
[n 1]
Z N Isotopic mass (u)
[n 2][n 3]
Half-life
Decay
mode

[n 4]
Daughter
isotope

Spin and
parity
[n 5][n 6]
Excitation energy[n 6]
240Es[1] 99 141 240.06892(43)# 6(2) s α (70%) 236Bk
β+ (25.2%) 240Cf
β+, SF (4.8%) (various)
241Es[2] 99 142 241.06854(24)# 4.3+2.4
−1.2
 s
α 237Bk 3/2−#
β+ 241Cf
242Es[3] 99 143 242.06975(35)# 17.8(16) s α (57%) 238Bk
β+ (41.7%) 242Cf
β+, SF (1.3%) (various)
243Es[3] 99 144 243.06955(25)# 23(3) s β+ (61%) 243Cf (7/2+,3/2−)
α (39%) 239Bk
244Es 99 145 244.07088(20)# 37(4) s β+ (94.69%) 244Cf
α (5.3%) 240Bk
β+, SF (0.011%) (various)
245Es[4] 99 146 245.07132(22)# 1.11(6) min β+ (51%) 245Cf (3/2−)
α (49%) 241Bk
246Es 99 147 246.07290(24)# 7.7(5) min β+ (90.1%) 246Cf 4−#
α (9.9%) 242Bk
β+, SF (.003%) (various)
247Es 99 148 247.07366(3)# 4.55(26) min β+ (93%) 247Cf 7/2+#
α (7%) 243Bk
SF (9×10−5%) (various)
248Es 99 149 248.07547(6)# 27(5) min β+ (99.75%) 248Cf 2−#, 0+#
α (.25%) 244Bk
β+, SF (3×10−5%) (various)
249Es 99 150 249.07641(3)# 102.2(6) min β+ (99.43%) 249Cf 7/2+
α (.57%) 245Bk
250Es 99 151 250.07861(11)# 8.6(1) h β+ (97%) 250Cf (6+)
α (3%) 246Bk
250mEs 200(150)# keV 2.22(5) h EC (99%) 250Cf 1(−)
α (1%) 246Bk
251Es 99 152 251.079992(7) 33(1) h EC (99.51%) 251Cf (3/2−)
α (.49%) 247Bk
252Es 99 153 252.08298(5) 471.7(19) d α (76%) 248Bk (5−)
EC (24%) 252Cf
β (.01%) 252Fm
253Es[n 7] 99 154 253.0848247(28) 20.47(3) d α 249Bk 7/2+
SF (8.7×10−6%) (various)
254Es 99 155 254.088022(5) 275.7(5) d α 250Bk (7+)
EC (10−4%) 254Cf
SF (3×10−6%) (various)
β (1.74×10−6%) 254Fm
254mEs 84.2(25) keV 39.3(2) h β (98%) 254Fm 2+
IT (3%) 254Es
α (.33%) 250Bk
EC (.078%) 254Cf
SF (.0045%) (various)
255Es 99 156 255.090273(12) 39.8(12) d β (92%) 255Fm (7/2+)
α (8%) 251Bk
SF (.0041%) (various)
256Es 99 157 256.09360(11)# 25.4(24) min β 256Fm (1+, 0−)
256mEs 0(100)# keV 7.6 h β (99.99%) 256Fm (8+)
β, SF (.002%) (various)
257Es 99 158 257.09598(44)# 7.7(2) d β 257Fm 7/2+#
α 253Bk
  1. mEs – 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. 6.0 6.1 # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
  7. Most common isotope

References

  1. Konki, J. (10 Jan 2017). "Towards saturation of the electron-capture delayed fission probability: The new isotopes 240Es and 236Bk". Physics Letters B 764: 265–270. doi:10.1016/j.physletb.2016.11.038. ISSN 0370-2693. Bibcode2017PhLB..764..265K. 
  2. Khuyagbaatar, J.; Albers, H. M.; Block, M.; Brand, H.; Cantemir, R. A.; Di Nitto, A.; Düllmann, Ch. E.; Götz, M. et al. (1 October 2020). "Search for Electron-Capture Delayed Fission in the New Isotope 244Md". Physical Review Letters 125 (14): 142504. doi:10.1103/PhysRevLett.125.142504. PMID 33064498. Bibcode2020PhRvL.125n2504K. http://urn.fi/URN:NBN:fi:jyu-202010066084. 
  3. 3.0 3.1 Antalic, S.; Heßberger, F. P.; Hofmann, S.; Ackermann, D.; Heinz, S.; Kindler, B.; Kojouharov, I.; Kuusiniemi, P. et al. (20 November 2009). "Studies of neutron-deficient mendelevium isotopes at SHIP". The European Physical Journal A 43 (1): 35. doi:10.1140/epja/i2009-10896-0. ISSN 1434-601X. Bibcode2010EPJA...43...35A. 
  4. Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (1 March 2021). "The NUBASE2020 evaluation of nuclear physics properties *" (in English). Chinese Physics C, High Energy Physics and Nuclear Physics 45 (3): 030001. doi:10.1088/1674-1137/abddae. ISSN 1674-1137. Bibcode2021ChPhC..45c0001K.