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Isotopes of Europium

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

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

All atomic nuclei of the chemical element europium are summarized under europium isotopes; these all consist of an atomic nucleus with 63 protons and, in the uncharged state, 63 electrons. The difference between each europium isotope is based on the number of neutrons in the nucleus.

 

Naturally Occurring Europium Isotopes

Europium is a chemical element from the group of rare earth metals (see under rare earths).

Natural occurrences of europium consist of 2 nuclides, the stable europium-153 and the radioisotope europium-151.

Atomic Mass maQuantityHalf-lifeSpin
Europium
Isotopic mixture		151,964 u100 %
Isotope 151Eu150,9198566(13) u47,81(6) %1.7 × 1018 a5/2+
Isotope 153Eu152,92124(2) u52,19(6) %stable5/2+

 

In addition, more than 30 other europium isotopes and a whole series of nuclear isomers have been characterized, all of which are unstable and are listed in the following isotope table:

 

Isotope Table: Europium

The two following tables list the most important data and properties of the Europium isotopes. Further information on the individual Europium 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
Europium-13013063Eu67129.96384(54) u
[129.9292822 u]
{-33.68282 MeV}		(1+)
Europium-13113163Eu68130.95784(43) u
[130.9232822 u]
{-39.27179 MeV}		3/2+
Europium-13213263Eu69131.95470(43) u
[131.9201422 u]
{-42.19668 MeV}		(0)
Europium-13313363Eu70132.94924(32) u
[132.9146822 u]
{-47.28264 MeV}		11/2-
Europium-13413463Eu71133.94640(32) u
[133.9118422 u]
{-49.92808 MeV}
Europium-13513563Eu72134.94187(21) u
[134.9073122 u]
{-54.14775 MeV}		11/2-
Europium-13613663Eu73135.93962(21) u
[135.9050622 u]
{-56.24361 MeV}		(7+)
Europium-136m136m63Eu73135.93962(21) u
[135.9050622 u]
{-56.24361 MeV}		(3+)
Europium-13713763Eu74136.935431(5) u
[136.9008732 u]
{-60.14564 MeV}		(11/2-)
Europium-13813863Eu75137.93371(3) u
[137.8991522 u]
{-61.74874 MeV}		(6-)138Gd
Europium-13913963Eu76138.929792(14) u
[138.8952342 u]
{-65.39833 MeV}		(11/2)-139Gd
Europium-139m139m63Eu76138.929792(14) u
[138.8952342 u]
{-65.39833 MeV}		(7/2+)
Europium-14014063Eu77139.92809(6) u
[139.8935322 u]
{-66.98373 MeV}		1+140Gd
Europium-140m140m63Eu77139.92809(6) u
[139.8935322 u]
{-66.98373 MeV}		(5-)
Europium-14114163Eu78140.924932(14) u
[140.8903742 u]
{-69.92539 MeV}		5/2+141Gd
Europium-141m141m63Eu78140.924932(14) u
[140.8903742 u]
{-69.92539 MeV}		11/2-
Europium-14214263Eu79141.92344(3) u
[141.8888822 u]
{-71.31518 MeV}		1+142Gd
Europium-142m142m63Eu79141.92344(3) u
[141.8888822 u]
{-71.31518 MeV}		8-
Europium-14314363Eu80142.920299(12) u
[142.8857412 u]
{-74.241 MeV}		5/2+143Gd
Europium-143m143m63Eu80142.920299(12) u
[142.8857412 u]
{-74.241 MeV}		11/2-
Europium-14414463Eu81143.918820(12) u
[143.8842622 u]
{-75.61868 MeV}		1+144Gd
Europium-144m144m63Eu81143.918817(12) u
[143.8842592 u]
{-75.62148 MeV}		(8-)
Europium-14514563Eu82144.916273(3) u
[144.8817152 u]
{-77.9912 MeV}		5/2+145Gd
149Tb
Europium-145m145m63Eu82144.916273(3) u
[144.8817152 u]
{-77.9912 MeV}		11/2-
Europium-14614663Eu83145.917211(6) u
[145.8826532 u]
{-77.11746 MeV}		4-146Gd
150Tb
Europium-146m146m63Eu83145.917211(6) u
[145.8826532 u]
{-77.11746 MeV}		9+
Europium-14714763Eu84146.9167523(2) u
[146.8821945 u]
{-77.54473 MeV}		5/2+147Gd
151Tb
Europium-147m147m63Eu84146.9167523(2) u
[146.8821945 u]
{-77.54473 MeV}
Europium-14814863Eu85147.918089(11) u
[147.8835312 u]
{-76.29961 MeV}		5-
Europium-148m148m63Eu85147.918089(11) u
[147.8835312 u]
{-76.29961 MeV}		9+
Europium-14914963Eu86148.917937(4) u
[148.8833792 u]
{-76.44119 MeV}		5/2+149Gd
Europium-149m149m63Eu86148.917937(4) u
[148.8833792 u]
{-76.44119 MeV}		11/2-
Europium-15015063Eu87149.919707(7) u
[149.8851492 u]
{-74.79245 MeV}		5-
Europium-150m150m63Eu87149.919707(7) u
[149.8851492 u]
{-74.79245 MeV}		0-
Europium-15115163Eu88150.9198566(13) u
[150.8852988 u]
{-74.6531 MeV}		5/2+151Gd
151Sm
Europium-151m151m63Eu88150.9198569(14) u
[150.8852991 u]
{-74.65282 MeV}		11/2-
Europium-15215263Eu89151.9217512(14) u
[151.8871934 u]
{-72.88829 MeV}		3-
Europium-152m1152m163Eu89151.9217512(14) u
[151.8871934 u]
{-72.88829 MeV}		0-
Europium-152m2152m263Eu89151.9217512(14) u
[151.8871934 u]
{-72.88829 MeV}		1-
Europium-15315363Eu90152.92124(2) u
[152.8866822 u]
{-73.36447 MeV}		5/2+
Europium-153m153m63Eu90152.92124(2) u
[152.8866822 u]
{-73.36447 MeV}		19/2-
Europium-15415463Eu91153.9229860(14) u
[153.8884282 u]
{-71.73808 MeV}		3-
Europium-154m1154m163Eu91153.9229860(14) u
[153.8884282 u]
{-71.73808 MeV}		2+
Europium-154m2154m263Eu91153.9229860(14) u
[153.8884282 u]
{-71.73808 MeV}		8-
Europium-15515563Eu92154.9229001(15) u
[154.8883423 u]
{-71.81809 MeV}		5/2+155Sm
Europium-15615663Eu93155.924763(4) u
[155.8902052 u]
{-70.08281 MeV}		0+156Sm
Europium-15715763Eu94156.925433(5) u
[156.8908752 u]
{-69.45871 MeV}		5/2+157Sm
Europium-15815863Eu95157.927799(11) u
[157.8932412 u]
{-67.2548 MeV}		(1-)158Sm
252Cf
Europium-15915963Eu96158.929100(5) u
[158.8945422 u]
{-66.04292 MeV}		5/2+159Sm
Europium-16016063Eu97159.931851(10) u
[159.8972932 u]
{-63.48038 MeV}		1160Sm
Europium-16116163Eu98160.933664(11) u
[160.8991062 u]
{-61.79159 MeV}		5/2+161Sm
Europium-16216263Eu99161.93698(4) u
[161.9024222 u]
{-58.70275 MeV}		162Sm
Europium-16316363Eu100162.93936(7) u
[162.9048022 u]
{-56.4858 MeV}		5/2+
Europium-16416463Eu101163.94269(12) u
[163.9081322 u]
{-53.38392 MeV}		(3)
Europium-16516563Eu102164.94555(15) u
[164.9109922 u]
{-50.71985 MeV}		5/2+
Europium-16616663Eu103165.94932(38) u
[165.9147622 u]
{-47.20812 MeV}
Europium-16716763Eu104166.95275(43) u
[166.9181922 u]
{-44.01309 MeV}		(5/2+)
Europium-16816863Eu105167.95734(54) u
[167.9227822 u]
{-39.73753 MeV}		(6-)

 

Radioactive Decay Properties

IsotopeRadioactive DecayExtern
Half-lifeDecay ModeProbabilityEnergy
789101112
Eu-1300.90(+49-29) msp → 129Sm100 %AL
Eu-13117.8(19) msp → 130Sm
EC/β+ → 131Sm		89(9) %
11(9) %
10.86(57) MeV		AL
Eu-132p → 131Sm
EC/β+ → 132Sm		?
?
12.88(50) MeV		AL
Eu-133ungelistetAL
Eu-1340.5(2) sEC/β+ → 134Sm
EC, p 133Pm		100 %
> 0 %		11.45(36) MeV
AL
Eu-1351.5(2) sEC/β+ → 135Sm
EC, p 134Pm		100 %
?		8.71(25) MeV
AL
Eu-1363.3(3) sEC/β+ → 136Sm
β+, p → 135Pm		99.91 %
0.09 %		10.57(20) MeV
AL
Eu-136m3.8(3) sEC/β+ → 136Sm
β+, p → 135Pm		99.91 %
0.09 %
AL
Eu-13711(2) sEC/β+ → 137Sm100 %7.88(4) MeVAL
Eu-13812.1(6) sEC/β+ → 138Sm100 %9.75(3) MeVAL
Eu-13917.9(6) sEC/β+ → 139Sm100 %6.982(17) MeVAL
Eu-139m10(2) μsIso → 139Eu100 %
Eu-1401.51(2) sEC/β+ → 140Sm100 %8.47(5) MeVAL
Eu-140m125(2) msEC/β+ → 140Sm
Iso → 140Eu		< 1 %
> 99 %
AL
Eu-14140.7(7) sEC/β+ → 141Sm100 %6.008(15) MeVAL
Eu-141m2.7(3) sEC/β+ → 141Sm
Iso → 141Eu		13 %
87 %
AL
Eu-1422.34(12) sEC/β+ → 142Sm100 %4.35 MeVAL
Eu-142m1.223(8) minEC/β+ → 142Sm100 %AL
Eu-1432.59(2) minEC/β+ → 143Sm100 %5.276(11) MeVAL
Eu-143m50.0(5) μsAL
Eu-14410.2(1) sEC/β+ → 144Sm100 %6.346(11) MeVAL
Eu-144m1.0(1) μsAL
Eu-1455.93(4) dEC/β+ → 145Sm100 %2.66(3) MeVAL
Eu-145m490(30) nsAL
Eu-1464.61(3) dEC/β+ → 146Sm100 %3.879(7) MeVAL
Eu-146m235(3) μsIso → 146Eu100 %AL
Eu-14724.1(6) dEC → 147Sm
α → 143Pm		99.9978(6) %
0.0022(6) %		1.722(3) MeV
2.991(3) MeV		AL
Eu-147m0.765(15) μs
Eu-14854.5(5) dEC/β+ → 148Sm
α → 144Pm		> 99 %
<< 1 %		3.037(10) MeV
2.692(10) MeV		AL
Eu-148m162(8) nsIso → 148Eu100.0 %
Eu-14993.1(4) dEC → 149Sm100 %0.695(4) MeVAL
Eu-1492.45(5) μsIso → 149Eu?
Eu-15036.9(9) aEC/β+ → 150Sm100 %2.259(6) MeVAL
Eu-150m12.8(1) hEC/β+ → 151Sm
β- → 150Gd
Iso → 150Eu		11(2) %
89(2) %
<< 1 %

AL
Eu-1511.7 × 1018 aα → 147Pm?1.9640(11) MeVAL
Eu-151m58.9(5) µsIso → 151Eu100 %AL
Eu-15213.517(9) aEC/β+ → 152Sm
β- → 152Gd		72.08(13) %
27.92(13) %		1.8743(18) MeV
1.8187(7) MeV		AL
Eu-152m19.3116(13) hEC/β+ → 152Sm
β- → 152Gd		27(3) %
73(3) %
AL
Eu-152m20.94(8) μsIso → 152Eu100 %0.1478 MeVAL
Eu-153stableAL
Eu-153m475(19) ns
Eu-1548.601(10) aEC/β+ → 154Sm
β- → 154Gd		0.018(12) %
99.982(12) %		0.717(20) MeV
1.9678(8) MeV		AL
Eu-154m12.2(1) μsIso → 154Eu?AL
Eu-154m246.3(4) minIso → 154Eu100 %
Eu-1554.753(14) aβ- → 155Gd100 %0.2518(9) MeVAL
Eu-15615.19(8) dβ- → 156Gd100 %2.452(3) MeVAL
Eu-15715.18(3) hβ- → 157Gd100 %1.365(4) MeVAL
Eu-15845.9(2) minβ- → 158Gd100 %3.434(10) MeVAL
Eu-15918.1(1) minβ- → 159Gd100 %2.518(4) MeVAL
Eu-16038(4) sβ- → 160Gd100 %4.461(10) MeVAL
Eu-16126(3) sβ- → 161Gd100 %3.714(11) MeVAL
Eu-16210.6(10) sβ- → 162Gd100 %5.58(3) MeVAL
Eu-1637.7(4) sβ- → 163Gd100 %4.83(6) MeVAL
Eu-1644.15(20) sβ- → 164Gd100 %6.39(5) MeVAL
Eu-1652.3(2) sβ- → 165Gd100 %5.73(6) MeVAL
Eu-1661.7(3) sβ- → 166Gd
β-, n 165Gd		100 %
?		7.32(30) MeV
1.17(38) MeV		AL
Eu-1671.3(5) sβ- → 167Gd
β-, n → 166Gd		100 %
?		6.8(5) MeV
2.45(44) MeV
Eu-1680.2(1) sβ- → 169Gd
β-, n → 168Gd		100 %
?		8.62(64) MeV
3.00(58) MeV

 

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 Europium 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 Europium 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.

 

NMR active Europium nuclides

Nuclide
quantity 1)
spin		Nuclear
magnetic
moment
μ/μN		Gyromagnetic ratio
{Quadrupole moment}		Resonant
frequency
v0 bei 1 T		Relative
sensitivity
H0 = const.
v0 = const. 3)
151Eu
47,81(6) %
5/2+		+ 3,4717(6)6,5477
{90,3(10)}		10,58560,17929
2,9006
153Eu
52,19(6) %
5/2+		+ 1,5324(3)2,9371
{241,2(21)}		4,67450,01544
1,2809

1) Quantity Percentage of natural occurrence.

2) Gyromagnetic ratio: 107 rad T-1 s-1
    Quadrupole moment: Q fm-2

3) Related to 1H = 1,000.

 

Radiation Protection

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

NuclideLimit ValueHASS limitSCDaughter NuclidesHalf-life
Eu-145106 Bq10 Bq/g5.9 d
Eu-146106 Bq10 Bq/g4.6 d
Eu-147106 Bq10 Bq/g0,2 TBq24.0 d
Eu-148106 Bq1 Bq/g0,03 TBq54.5 d
Eu-149107 Bq10 Bq/g2 TBq93.1 d
Eu-150106 Bq0,1 Bq/g36.4 d
Eu-152106 Bq0,1 Bq/g0,06 TBq1 Bq cm-213.5 a
Eu-152m106 Bq100 Bq/g0,2 TBq10 Bq cm-29.3 h
Eu-154106 Bq0,1 Bq/g0,06 TBq1 Bq cm-28.6 a
Eu-155107 Bq1 Bq/g2 TBq10 Bq cm-24.8 a
Eu-156106 Bq10 Bq/g15.2 d
Eu-157106 Bq100 Bq/g15.2 h
Eu-158105 Bq10 Bq/g45.9 min

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

 

Literature Sources and References

Properties of the Europium 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.

Europium: NMR properties - 151Eu-NMR, 153Eu-NMR

[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.

[9] - E. May, M. Thoennessen:
Discovery of samarium, europium, Dysprosium, and Dysprosium isotopes.
In: Atomic Data and Nuclear Data Tables, (2013), DOI 10.1016/j.adt.2012.01.007.

 

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