Cesium-122m3

Properties and data of the isotope ¹²²Cs.

Content

General data

Name of the isotope:Cesium-122m3; Cs-122m3Symbol:¹²²Cs or 12255CsMass number A:122 (= number of nucleons)Atomic number Z:55 (= number of protons)Neutrons N:67Isotopic mass:121.91611(4) u (atomic weight of Cesium-122m3)
Excitation energy: 127.07(16) keVNuclide mass:121.8859401 u (calculated nuclear mass without electrons)Mass excess:-78.14303 MeVMass defect:1.094816132 u (per nucleus)Nuclear binding energy:1019.81465806 MeV (per nucleus)
8.35913654 MeV (average binding energy per nucleon)Half-life:0.36(2) sDecay constant λ:1.9254088348887 s^-1Specific activity α:9.582713402203 × 10⁺²¹ Bq g^-1
258992254113.62 Ci g^-1Spin and parity:
(nuclear angular momentum)(5)-

Radioactive Decay

Half-life T_½ = 0.36(2) s respectively 3.6 × 10^-1 seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
Iso	¹²²Cs	100 %

Nuclear Isomers

Nuclear isomers or excited states with the activation energy in keV related to the ground state.

Nuclear Isomer	Excitation Energy	Half-life	Spin
¹²²Cs		21.18(19) s	1+
^122m1Cs	45.87(12) keV	1 μs	(3)+
^122m2Cs	140(3) keV	3.70(11) min	8(-)

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 67) and isobaric (same nucleon number A = 122) with Cesium-122m3. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 67	Isobar A = 122
38	¹⁰⁵Sr
39	¹⁰⁶Y
40	¹⁰⁷Zr
41	¹⁰⁸Nb
42	¹⁰⁹Mo
43	¹¹⁰Tc
44	¹¹¹Ru	¹²²Ru
45	¹¹²Rh	¹²²Rh
46	¹¹³Pd	¹²²Pd
47	¹¹⁴Ag	¹²²Ag
48	¹¹⁵Cd	¹²²Cd
49	¹¹⁶In	¹²²In
50	¹¹⁷Sn	¹²²Sn
51	¹¹⁸Sb	¹²²Sb
52	¹¹⁹Te	¹²²Te
53	¹²⁰I	¹²²I
54	¹²¹Xe	¹²²Xe
55	¹²²Cs	¹²²Cs
56	¹²³Ba	¹²²Ba
57	¹²⁴La	¹²²La
58	¹²⁵Ce	¹²²Ce
59	¹²⁶Pr	¹²²Pr
60	¹²⁷Nd
61	¹²⁸Pm
62	¹²⁹Sm
63	¹³⁰Eu