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Isotopes of Caesium

List, data and properties of all known isotopes of Caesium as well as radioactive decay products and intermediate products.

 

Caesium isotopes

All atomic nuclei of the chemical element cesium (also: caesium) are summarized under cesium isotopes; these all consist of an atomic nucleus with 55 protons and, in the uncharged state, 55 electrons. The difference between the individual cesium isotopes is based on the number of neutrons in the nucleus.

Cesium, Cs, is a so-called mononuclide element or pure element, i. H. Cesium occurs in nature only in the form of the cesium isotope 133Cs; a total of 39 cesium isotopes and 23 nuclear isomers are known.

 

Isotope Table: Caesium

 

Atomic Properties

Isotope
Nuclide
ZANNameAtomic Mass
[Nuclear Mass]
{Mass Excess}
Spin I
(h/2π)
μParent
123456789
112Cs5511257Caesium-112111.95031(9) u
[111.9201401 u]
{-46.28594 MeV}
(1+)
113Cs5511358Caesium-113112.944428(9) u
[112.9142581 u]
{-51.76498 MeV}
(3/2+)
114Cs5511459Caesium-114113.94130(8) u
[113.9111301 u]
{-54.6787 MeV}
(1+)114Ba
115Cs5511560Caesium-115114.93591(11) u
[114.9057401 u]
{-59.69945 MeV}
(9/2+)115Ba
116Cs5511661Caesium-116159.3339(11) u
[159.3037301 u]
{40365.26785 MeV}
(1+)116Ba
116mCs5511661Caesium-116m159.3339(11) u
[159.3037301 u]
{40365.26785 MeV}
4+,5,6
117Cs5511762Caesium-117116.92862(7) u
[116.8984501 u]
{-66.49004 MeV}
(9/2+)117Ba
117mCs5511762Caesium-117m116.92862(7) u
[116.8984501 u]
{-66.49004 MeV}
(3/2+)
118Cs5511863Caesium-118117.926560(14) u
[117.8963901 u]
{-68.40892 MeV}
2+ 3.870(5)118Ba
118mCs5511863Caesium-118m117.926560(14) u
[117.8963901 u]
{-68.40892 MeV}
(6,7,8)5.4(11)
119Cs5511964Caesium-119118.922377(15) u
[118.8922071 u]
{-72.30536 MeV}
9/2++ 5.45(3)119Ba
119mCs5511964Caesium-119m118.922377(15) u
[118.8922071 u]
{-72.30536 MeV}
3/2(+)+ 0.837(5)
120Cs5512065Caesium-120119.920677(11) u
[119.8905071 u]
{-73.8889 MeV}
2(+)+ 3.86(2)120Ba
120mCs5512065Caesium-120m119.920677(11) u
[119.8905071 u]
{-73.8889 MeV}
(7-)
121Cs5512166Caesium-121120.917227(15) u
[120.8870571 u]
{-77.10255 MeV}
(3/2)++ 0.769(4)121Ba
121mCs5512166Caesium-121m120.917227(15) u
[120.8870571 u]
{-77.10255 MeV}
9/2(+)+ 5.40(3)
122Cs5512267Caesium-122121.91611(4) u
[121.8859401 u]
{-78.14303 MeV}
1+- 0.133(2)122Ba
122m1Cs5512267Caesium-122m1121.91611(4) u
[121.8859401 u]
{-78.14303 MeV}
(3)+
122m2Cs5512267Caesium-122m2121.91611(4) u
[121.8859401 u]
{-78.14303 MeV}
8(-)+ 4.76(2)
122m3Cs5512267Caesium-122m3121.91611(4) u
[121.8859401 u]
{-78.14303 MeV}
(5)-
123Cs5512368Caesium-123122.912996(13) u
[122.8828261 u]
{-81.0437 MeV}
1/2++ 1.375(7)123Ba
123m1Cs5512368Caesium-123m1122.912996(13) u
[122.8828261 u]
{-81.0437 MeV}
(11/2)-
123m2Cs5512368Caesium-123m2122.912996(13) u
[122.8828261 u]
{-81.0437 MeV}
(9/2+)
124Cs5512469Caesium-124123.912258(9) u
[123.8820881 u]
{-81.73115 MeV}
1++ 0.672(3)124Ba
124mCs5512469Caesium-124m123.912258(9) u
[123.8820881 u]
{-81.73115 MeV}
(7)+
125Cs5512570Caesium-125124.909728(8) u
[124.8795581 u]
{-84.08783 MeV}
1/2(+)+ 1.407(7)125Ba
125mCs5512570Caesium-125m124.909728(8) u
[124.8795581 u]
{-84.08783 MeV}
(11/2-)
126Cs5512671Caesium-126125.909446(11) u
[125.8792761 u]
{-84.35051 MeV}
1++ 0.776(4)126Ba
126m1Cs5512671Caesium-126m1125.909446(11) u
[125.8792761 u]
{-84.35051 MeV}
126m2Cs5512671Caesium-126m2125.909446(11) u
[125.8792761 u]
{-84.35051 MeV}
127Cs5512772Caesium-127126.907417(6) u
[126.8772471 u]
{-86.24051 MeV}
1/2++ 1.457(7)127Ba
127mCs5512772Caesium-127m126.907417(6) u
[126.8772471 u]
{-86.24051 MeV}
(11/2)-
128Cs5512873Caesium-128127.907749(6) u
[127.8775791 u]
{-85.93125 MeV}
1++ 0.972(5)128Ba
129Cs5512974Caesium-129128.906066(5) u
[128.8758961 u]
{-87.49896 MeV}
1/2++ 1.489(8)129Ba
130Cs5513075Caesium-130129.906709(9) u
[129.8765391 u]
{-86.90001 MeV}
1++1.458(7)
130mCs5513075Caesium-130m129.906709(9) u
[129.8765391 u]
{-86.90001 MeV}
5-+ 0.628(4)
131Cs5513176Caesium-131130.905465(5) u
[130.8752951 u]
{-88.05879 MeV}
5/2++ 3.536(3)131Ba
132Cs5513277Caesium-132131.9064377(11) u
[131.8762678 u]
{-87.15272 MeV}
2++ 2.219(7)
133Cs5513378Caesium-133132.90545196(6) u
[132.8752821 u]
{-88.07093 MeV}
7/2++2.5778(14)133Ba
133Xe
134Cs5513479Caesium-134133.906718503(17) u
[133.8765486 u]
{-86.89115 MeV}
4++2.9893(14)134Ba
134Xe
134mCs5513479Caesium-134m133.906718503(17) u
[133.8765486 u]
{-86.89115 MeV}
8-+ 1.0959(6)
135Cs5513580Caesium-135134.9059772(11) u
[134.8758073 u]
{-87.58167 MeV}
7/2++ 2.7283(13)135Xe
135mCs5513580Caesium-135m134.9059772(11) u
[134.8758073 u]
{-87.58167 MeV}
19/2-+ 2.18(1)
136Cs5513681Caesium-136135.9073116(20) u
[135.8771417 u]
{-86.33869 MeV}
5++ 3.705(15)
136mCs5513681Caesium-136m135.9073116(20) u
[135.8771417 u]
{-86.33869 MeV}
8-+ 1.317(7)
137Cs5513782Caesium-137136.9070893(3) u
[136.8769194 u]
{-86.54576 MeV}
7/2++ 2.8374(14)137Xe
252Cf
138Cs5513883Caesium-138137.911017(10) u
[137.8808471 u]
{-82.88713 MeV}
3-+ 0.699(4)138Xe
138m1Cs5513883Caesium-138m1137.911017(10) u
[137.8808471 u]
{-82.88713 MeV}
6-+1.710(9)
139Cs5513984Caesium-139138.913364(3) u
[138.8831941 u]
{-80.70091 MeV}
7/2++2.688(4)139Xe
140Cs5514085Caesium-140139.917283(9) u
[139.8871131 u]
{-77.05039 MeV}
1-+ 0.134(1)140Xe
141Cs5514186Caesium-141140.920045(10) u
[140.8898751 u]
{-74.4776 MeV}
7/2++ 2.431(10)141Xe
142Cs5514287Caesium-142141.924300(8) u
[141.8941301 u]
{-70.5141 MeV}
0-142Xe
143Cs5514388Caesium-143142.927347(8) u
[142.8971771 u]
{-67.67583 MeV}
3/2++ 0.869(4)143Xe
144Cs5514489Caesium-144143.932075(22) u
[143.9019051 u]
{-63.27173 MeV}
1(-)- 0.545(3)144Xe
144mCs5514489Caesium-144m143.932075(22) u
[143.9019051 u]
{-63.27173 MeV}
(>3)
145Cs5514590Caesium-145144.935529(10) u
[144.9053591 u]
{-60.05435 MeV}
3/2++ 0.783(4)145Xe
146Cs5514691Caesium-146145.940622(3) u
[145.9104521 u]
{-55.31025 MeV}
1-- 0.514(2)146Xe
147Cs5514792Caesium-147146.944262(9) u
[146.9140921 u]
{-51.91961 MeV}
(3/2+)147Xe
148Cs5514893Caesium-148147.949639(14) u
[147.9194691 u]
{-46.91097 MeV}
149Cs5514994Caesium-149148.95357(43) u
[148.9234001 u]
{-43.24927 MeV}
150Cs5515095Caesium-150149.95902(43) u
[149.9288501 u]
{-38.17262 MeV}
151Cs5515196Caesium-151150.96325(54) u
[150.9330801 u]
{-34.2324 MeV}

 

Radioactive Decay Properties

IsotopeRadioactive DecayAEExtern
Half-lifeDecay ModeProbabilityEnergy
1101112131415
Cs-1120.49(3) msp → 111Xe
α → 108I
> 97.4 %
< 0.26 %

3.93(12) MeV
AL
Cs-11317.7(4) μsp → 112Xe100 %AL
Cs-1140.57(2) sEC/β+114Xe
EC, p → 113I
EC, α → 110Te
α → 110I
99.982(6) %
8.7(13) %
0.19(3) %
0.018(6) %
12.40(7) MeV


3.36(5) MeV
AL
Cs-1151.4(8) sEC/β+115Xe
β+, p → 114I
99.93 %
0.07 %
8.96(10) MeV
AL
Cs-1160.70(4) sEC/β+116Xe
EC, p → 115I
EC, α → 112Te
97.1 %
2.8(7) %
0.049(25) %
11.0(1) MeV

AL
Cs-116m3.85(13) sβ+116Xe
β+, p → 115I
EC, α → 112Te
99.5 %
0.51(15) %
0.008(2) %


100 keVAL
Cs-1178.4(6) sEC/β+117Xe100 %7.69(6) MeV+yAL
Cs-117m6.5(4) sEC/β+117Xe?+z keVAL
Cs-11814(2) sEC/β+118Xe
EC, p → 117I
EC, α → 114Te
99.95 %
0.042 %
0.0024 %
9.670(16) MeV

AL
Cs-118m17(3) sβ+118Xe
β+, p → 117I
EC, α → 114Te
99.95 %
0.042 %
0.0024 %


180 keVAL
Cs-11943.0(2) sEC/β+119Xe100 %6.489(17) MeVAL
Cs-119m30.4(1) sEC/β+119Xe100 %50 keVAL
Cs-12061.3(11) sβ+120Xe
β+, p → 118I
β+, α → 116Te
< 100 %
<< 1%
<<
8.284(15) MeV

AL
Cs-120m57(6) sEC/β+120Xe100 %100 keVAL
Cs-121155(4) sβ+121Xe100 %5.379(18) MeVAL
Cs-121m122(3) sβ+121Xe
Iso → 121Cs
83 %
17 %

68.5(3) keVAL
Cs-12221.18(19) sEC/β+122Xe100 %7.21(4) MeVAL
Cs-122m11 μs45.87(12) keVAL
Cs-122m23.70(11) minEC/β+122Xe100 %140(3) keVAL
Cs-122m30.36(2) sIso → 122Cs100 %127.07(16) keVAL
Cs-1235.88(3) minEC/β+123Xe100 %4.205(15) MeVAL
Cs-123m11.64(12) sIso → 123Cs100 %156.27(5) keVAL
Cs-123m2114(5) ns231.63+x keVAL
Cs-12430.9(4) sEC/β+124Xe100 %5.93(8) MeVAL
Cs-124m6.3(2) sIso → 124Cs100 %462.63(14) keVAL
Cs-12546.7(1) minEC/β+125Xe100 %3.105(8) MeVAL
Cs-125m0.90(3) msIso → 125Cs100 %266.1(11) keVAL
Cs-1261.64(2) minEC/β+126Xe100 %4.796(11) MeVAL
Cs-126m11 μs273.0(7) keVAL
Cs-126m2171(14) μs596.1(11) keVAL
Cs-1276.25(10) hEC/β+127Xe100 %2.081(7) MeVAL
Cs-127m55(3) μsIso → 127Cs100 %452.23(21) keVAL
Cs-1283.640(14) minEC/β+128Xe100 %3.929(6) MeVAL
Cs-12932.06(6) hEC/β+129Xe100 %1.197(5) MeVAL
Cs-13029.21(4) minEC/β+130Xe
β-130Ba
98.4 %
1.6 %
2.981(8) MeV
0.362(9) MeV
AL
Cs-130m3.46(6) minIso → 130Cs
β+130Xe
99.83 %
0.16 %

163.25(11) keVAL
Cs-1319.689(16) dEC → 131Xe100 %0.355(5) MeVAL
Cs-1326.480(6) dEC/β+132Xe
β-132Ba
98.13(9) %
1.87(9) %
2.1263(10) MeV
1.2823(15) MeV
AL
Cs-133stableAL
Cs-1342.0652(4) aβ-134Ba
EC → 134Xe
99.9997(1) %
0.0003(1) %
2.0587(3) MeV
1.234668(18) MeV
AL
Cs-134m2.912(2) hIso → 134Cs100 %138.7441(26) keVAL
Cs-1352.3(3) × 106 aβ-135Ba100 %2.689(10) MeVAL
Cs-135m53(2) minIso → 135Cs100 %1632.9(15) keVAL
Cs-13613.01(5) dβ-136Ba100 %2.5482(19) MeVAL
Cs-136m17.5(2) sβ-136Ba
Iso → 136Cs
?
?

517.9(1) keVAL
Cs-13730.08(9) aβ-137Ba100 %1.17563(17) MeVAL
Cs-13832.5(2) minβ-138Ba100 %5.375(9) MeVAL
Cs-138m12.91(8) minβ-138Ba
Iso → 138Cs
19(2) %
81(2) %

79.9(3) keVAL
Cs-1399.27(5) minβ-139Ba100 %4.213(3) MeVAL
Cs-14063.7(3) sβ-140Ba100 %6.219(10) MeVAL
Cs-14124.84(16) sβ-141Ba
β-, n → 140Ba
99.96 %
0.035(3) %
5.255(10) MeV
0.721(12) MeV
AL
Cs-1421.684(14) sβ-142Ba
β-, n → 141Ba
99.9 %
0.090(4) %
7.328(8) MeV
1.147(9) MeV
AL
Cs-1431.791(7) sβ-143Ba
β-, n → 142Ba
98.36 %
1.64(7) %
6.262(10) MeV
2.095(10) MeV
AL
Cs-144994(6) msβ-144Ba
β-, n → 143Ba
96.97 %
3.03(13) %
8.496(20) MeV
2.595(21) MeV
AL
Cs-144m< 1 sβ-144Ba?300 keVAL
Cs-145587(5) msβ-145Ba
β-, n → 144Ba
85.3 %
14.7(9) %
7.462(12) MeV
3.641(11) MeV
AL
Cs-146322.0(13) msβ-146Ba
β-, n → 145Ba
85.8 %
14.2(5) %
9.637(21) MeV
4.134(9) MeV
AL
Cs-147230(1) msβ-147Ba
β-, n → 146Ba
71.5 %
28.5(17) %
8.344(21) MeV
4.956(22) MeV
AL
Cs-148146(6) msβ-148Ba
β-, n → 147Ba
74.9 %
25.1(25) %
10.68(6) MeV
5.282(24) MeV
AL
Cs-149113(8) msβ-149Ba
β-, n → 148Ba
100 %
?
9.87(59) MeV
6.27(40) MeV
AL
Cs-15084(8) msβ-150Ba
β-, n → 149Ba
80 %
20(10)
11.73(50) MeV
6.88(59) MeV
AL
Cs-15169(26) msβ-151Ba
β-, n → 150Ba
100 %
?
10.71(64) MeV
7.60(58) MeV
AL

 

Notes (related to the columns):

1 - nuclide, isotope symbol.
2 - Z = number of protons (atomic number).
3 - Mass number A.
4 - N = number of neutrons.
5 - Identification of the Caesium isotope.
6 - Relative atomic mass of the Caesium 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.
7 - Nuclear spin I, unit: h/2π.
8 - Nuclear magnetic moment μmag.
9 - 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.
10 - Decay: Half-live of the Caesium isotope (a = years; ; d = days; h = hours; min = minutes; s = seconds).
11 - Decay: 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.
12 - Decay percentage in percent (%).
13 - Decay energy; Particle energy related to decay type.
14 - AE = Excitation energy for metastable nuclei.
15 - 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 Caesium nuclides

Nuclide
quantity 1)
spin
Nuclear magnetic
moment
μ/μN
Gyromagnetic
ratio
107 rad T-1 s-1
Quadrupole
moment
Q fm-2
Resonant
frequency
v0 bei 1 T
Relative
sensitivity
H0 = const.
v0 = const. 2)
133Cs
100 %
7/2+
+2,5778(14)3,5339- 0,343(10)5,62340,04838
2,7736

1) Quantity Percentage of natural occurrence.

2) 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 Caesium radionuclides:

NuclideLimit ValueHASS limitSCDaughter NuclidesHalf-life
Cs-125104 Bq10 Bq/g46.7 min
Cs-127105 Bq100 Bq/g6.3 h
Cs-129105 Bq10 Bq/g10 Bq cm-232.2 h
Cs-130106 Bq100 Bq/g29.2 min
Cs-131106 Bq1000 Bq/g20 TBq100 Bq cm-29.7 d
Cs-132105 Bq10 Bq/g1 Bq cm-26.5 d
Cs-134104 Bq0,1 Bq/g1 Bq cm-22.1 a
Cs-134m105 Bq1000 Bq/g100 Bq cm-22.9 h
Cs-135107 Bq100 Bq/g100 Bq cm-22.3 × 106 a
Cs-136105 Bq1 Bq/g0,03 TBq1 Bq cm-213.0 d
Cs-137+104 Bq0,1 Bq/g0,1 TBq1 Bq cm-2Ba-137m30.2 a
Cs-138104 Bq10 Bq/g1 Bq cm-233.4 min

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

 

Literature Sources and References

Properties of the Caesium 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.

Caesium: NMR properties - 133Cs-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.

 


Category: Isotopes

Last update: 05.07.2020



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