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Isotopes of Einsteinium

List, data and properties of all known isotopes of Einsteinium.

Content
Atomic properties
Decay properties
NMR active nuclides
Radiation protection
References
Einsteinium isotopes

Einsteinium isotopes include all of the atomic nuclei of the chemical element einsteinium; these consist of an atomic nucleus with 99 protons and in the uncharged state of 99 electrons. The difference between the individual einsteinium isotopes lies in the number of neutrons in the nucleus - and thus in the mass number.

Einsteinium

is an artificially created chemical element, of which 17 different isotopes have been created and characterized so far. Einsteinium-253 was the first nuclide to be discovered in the nuclear fallout of a hydrogen bomb test in 1952.

Einsteinium-252 has the longest half-life at 472 days.

 

Isotope Table: Einsteinium

The two following tables list the most important data and properties of the Einsteinium isotopes. Further information on the individual Einsteinium isotopes is listed on separate pages and can be accessed via the link in column 1.

 

Atomic Properties

Isotope
Nuclide		ENAtomic Mass
[Nuclear Mass]
{Mass Excess}		Spin I
(h/2π)		Parent
123456
Einsteinium-24024099Es141240.06892(43) u
[240.0146185 u]
{64.19857 MeV}		(1+)
Einsteinium-24124199Es142241.06856(24) u
[241.0142585 u]
{63.86323 MeV}		(3/2-)245Md
Einsteinium-24224299Es143242.06957(27) u
[242.0152685 u]
{64.80404 MeV}		246Md
Einsteinium-24324399Es144243.06951(22) u
[243.0152085 u]
{64.74815 MeV}		(7/2+)247Md
Einsteinium-24424499Es145244.07088(19) u
[244.0165785 u]
{66.02429 MeV}		248Md
Einsteinium-24524599Es146245.07125(21) u
[245.0169485 u]
{66.36895 MeV}		(3/2-)249Md
Einsteinium-24624699Es147246.07289(24) u
[246.0185885 u]
{67.8966 MeV}		250Md
Einsteinium-24724799Es148247.073622(21) u
[247.0193205 u]
{68.57845 MeV}		(7/2+)251Md
247Fm
Einsteinium-24824899Es149248.07547(6) u
[248.0211685 u]
{70.29985 MeV}		(2-,0+)
Einsteinium-24924999Es150249.07641(3) u
[249.0221085 u]
{71.17546 MeV}		7/2+
Einsteinium-25025099Es151250.07861(11) u
[250.0243085 u]
{73.22474 MeV}		(6+)250Fm
Einsteinium-250m250m99Es151250.07861(11) u
[250.0243085 u]
{73.22474 MeV}		1(-)
Einsteinium-25125199Es152251.079992(6) u
[251.0256905 u]
{74.51207 MeV}		3/2-255Md
251Fm
Einsteinium-25225299Es153252.08298(5) u
[252.0286785 u]
{77.29537 MeV}		(5-)256Md
Einsteinium-25325399Es154253.0848213(13) u
[253.0305198 u]
{79.01053 MeV}		7/2+257Md
253Fm
253Cf
Einsteinium-25425499Es155254.088021(4) u
[254.0337195 u]
{81.99103 MeV}		(7+)258Md
Einsteinium-254m254m99Es155254.088021(4) u
[254.0337195 u]
{81.99103 MeV}		2+
Einsteinium-25525599Es156255.090274(12) u
[255.0359725 u]
{84.08969 MeV}		(7/2+)255Cf
Einsteinium-25625699Es157256.09360(11) u
[256.0392985 u]
{87.18784 MeV}		(1+,0-)
Einsteinium-256m256m99Es157256.09360(11) u
[256.0392985 u]
{87.18784 MeV}		(8+)
Einsteinium-25725799Es158257.09598(44) u
[257.0416785 u]
{89.40479 MeV}		(7/2+)

 

Radioactive Decay Properties

IsotopeRadioactive DecayExtern
Half-lifeDecay ModeProbabilityEnergy
789101112
Es-2406(2) sα → 236Bk
EC/β+ → 240Cf
EC, SS div		70(10) %
30(10) %
8.23(57) MeV
Es-241ca. 8 sα → 237Bk
EC/β+ → 241Cf		?
?		8.25(2) MeV
4.54(28) MeV		AL
Es-24213.5(25) sα → 238Bk
EC/β+ → 242Cf		> 0 %
> 0 %		8.16(2) MeV
5.41(26) MeV		AL
Es-24321(2) sα → 239Bk
EC/β+ → 243Cf
SF 		61(6) %
39(6) %
< 1 %		8.072(10) MeV
3.76(24) MeV
AL
Es-24437(4) sα → 240Bk
EC → 244Cf		ca. 4 %
ca. 96 %		7.94(10) MeV
4.55(18) MeV		AL
Es-2451.1(1) minα → 241Bk
EC → 245Cf		40(10) %
60(10) %		7.9090(3) MeV
2.98(20) MeV		AL
Es-2467.5(5) minα → 242Bk
EC/β+ → 246Cf		9.9(18) %
90.1(18) %		7.74(10) MeV
3.81(22) MeV		AL
Es-2474.55(26) minα → 243Bk
EC/β+ → 247Cf		7 %
93 %
AL
Es-24824(3) minα → 244Bk
EC → 248Cf		0.25 %
99.7(3) %		7.16(5) MeV
3.06(5) MeV		AL
Es-249102.2(6) minα → 245Bk
EC/β+ → 249Cf		0.57(8) %
99.43(8) %		6.94(3) MeV
1.45(3)		AL
Es-2508.6(1) hα → 246Bk
EC → 250Cf		< 3 %
> 97 %		6.834(117) MeV
2.055(100) MeV		AL
Es-250m2.22(5) hEC → 250Cf≤ 100 %AL
Es-25133(1) hα → 247Bk
EC → 251Cf		0.5(2) %
99.5(2) %		6.598(3) MeV
0.377(7) MeV		AL
Es-252471.7(19) dα → 248Bk
EC → 252Cf		78(2) %
22(2) %		6.79(5) MeV
1.26(5) MeV		AL
Es-25320.47(3) dα → 249Bk
SF div		< 100 %
0.0000087 %		6.73924(5) MeV
AL
Es-254275.7(5) dα → 250Bk
EC → 254Cf
SF div
β- → 254Fm		ca. 100 %
?
< 1 %
< 1 %		6.6157(15) MeV
0.649(12) MeV

1.088(3) MeV		AL
Es-254m39.3(2) hβ- → 254Fm
Iso → 254Es
α → 250Bk
EC → 254Cf
SF div
< 3 %
0.32(1) %
0.076(7) %
< 0.045 %



AL
Es-25539.8(12) dα → 251Bk
SF div
β- → 255Fm		8.0(4) %
0.0041(2) %
92 %		6.4363(13) MeV

0.290(10) MeV		AL
Es-25625.4(24) minβ- → 256Fm100 %1.70(10) MeVAL
Es-256m7.6 hβ- → 256Fm
SF, β- → 		99.998 %
0.002 %
AL
Es-2577.7(2) dβ- → 257Fm
SF div		?
?		0.81(41) MeV
AL

 

Notes (related to the columns):

1 - name of the nuclide, isotope.
2 - E: isotope symbol with mass number (superscript; number of nucleons) and Atomic number (subscript; number of protons).
3 - N: number of neutrons.
4 - relative atomic mass of the Einsteinium isotope (isotopic mass including electrons) and the mass of the atomic nucleus in square brackets (nuclear mass, nuclide mass without electrons), each related to 12C = 12.00000 [2]. In addition, the mass excess is given in MeV.
5 - nuclear spin I, unit: h/2π.
6 - source nuclides: Possible, assumed or actual source nuclides (mother nuclides, parent nuclides). If applicable, the corresponding decay modes can be found in the data for the respective starting nuclide.

7 - isotope notation in short form.
8 - decay: half-live of the Einsteinium isotope (a = years; ; d = days; h = hours; min = minutes; s = seconds).
9 - decay mode: type of decay into the respective daughter nuclides with n = neutron emission; p = proton emission; α = alpha decay; β- = beta minus decay with electron emission; EC = electron capture; β+ = positron emission; ε = β+ and/or EC; Iso = isomeric transition; CD = cluster decay; SF = spontaneous decay.
10 - decay probability in percent (%).
11 - decay energy; Particle energy related to decay type.
12 - other information and notes: AL = Adopted Levels (link to external data [1]).

Miscellaneous:

()- Numbers in brackets: uncertainty to represent the spread of the reported value.
~ - Theoretical values or systematic trends.
  - unlisted-: Nuclides that have already been mentioned in the literature but for some reason can no longer be found in the current nuclide tables because their discovery e.g. has not confirmed.

 

Radiation Protection

According to the Radiation Protection Ordinance (StrlSchV 2018, Germany), the following values (columns 1 to 7) apply to the handling of Einsteinium radionuclides:

NuclideLimit ValueHASS limitSCDaughter NuclidesHalf-life
Es-250106 Bq100 Bq/g8.6 h
Es-251107 Bq100 Bq/g33.0 h
Es-253105 Bq100 Bq/g1 Bq cm-220.5 d
Es-254+104 Bq0,1 Bq/g1 Bq cm-2Bk-250275.7 d
Es-254m+106 Bq10 Bq/g1 Bq cm-2Bk-250, Fm-25439.3 h

(HASS = High-Activity Sealed Radioactive Sources; SC = surface contamination)

 

Literature Sources and References

Properties of the Einsteinium nucleides

[1] - NuDat: National Nuclear Data Center, Brookhaven National Laboratory, based on ENSDF and the Nuclear Wallet Cards.

[2] - G. Audi et. al.: The NUBASE evaluation of nuclear and decay properties. Nuclear Physics, (2003), DOI 10.1016/j.nuclphysa.2003.11.001.

[3] - Live Chart of Nuclides. Nuclear structure and decay data.

Einsteinium: NMR properties

[4] - N. J. Stone: Table of nuclear magnetic dipole and electric quadrupole moments. Atomic Data and Nuclear Data Tables, (2005), DOI 10.1016/j.adt.2005.04.001.

[5] - Pekka Pyykkö: Year-2008 nuclear quadrupole moments. Molecular Physics, (2008), DOI 10.1080/00268970802018367.

[6] - Pekka Pyykkö: Year-2017 nuclear quadrupole moments. Molecular Physics, (2018), DOI 10.1080/00268976.2018.1426131.

[7] - N. J. Stone: Table of recommended nuclear magnetic dipole moments. IAEA, (2019).

More sources:

[8] - Isotopic abundances, atomic weights and isotopic masses: see respective keyword.

 

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Last update: 2022-12-12

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