Cesium-119m

Properties and data of the isotope ¹¹⁹Cs.

Content

General data

Name of the isotope:Cesium-119m; Cs-119mSymbol:¹¹⁹Cs or 11955CsMass number A:119 (= number of nucleons)Atomic number Z:55 (= number of protons)Neutrons N:64Isotopic mass:118.922377(15) u (atomic weight of Cesium-119m)
Excitation energy: 50 keVNuclide mass:118.8922071 u (calculated nuclear mass without electrons)Mass excess:-72.30536 MeVMass defect:1.062554384 u (per nucleus)Nuclear binding energy:989.76303337 MeV (per nucleus)
8.31733641 MeV (average binding energy per nucleon)Half-life:30.4(1) sDecay constant λ:0.022800894097367 s^-1Specific activity α:1.163645728702 × 10⁺²⁰ Bq g^-1
3144988455.9516 Ci g^-1Spin and parity:
(nuclear angular momentum)3/2(+)Magnetic dipole moment:μ(μ_N) = + 0.837(5)Quadrupole moment Q:+ 0.90(1) barn (100 fm²)Nuclear g-factor:g_l = 0.558

Radioactive Decay

Half-life T_½ = 30.4(1) s respectively 3.04 × 10¹ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
EE/β⁺	¹¹⁹Xe	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
¹¹⁹Cs		43.0(2) s	9/2+

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 64) and isobaric (same nucleon number A = 119) with Cesium-119m. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 64	Isobar A = 119
36	¹⁰⁰Kr
37	¹⁰¹Rb
38	¹⁰²Sr
39	¹⁰³Y
40	¹⁰⁴Zr
41	¹⁰⁵Nb
42	¹⁰⁶Mo
43	¹⁰⁷Tc	¹¹⁹Tc
44	¹⁰⁸Ru	¹¹⁹Ru
45	¹⁰⁹Rh	¹¹⁹Rh
46	¹¹⁰Pd	¹¹⁹Pd
47	¹¹¹Ag	¹¹⁹Ag
48	¹¹²Cd	¹¹⁹Cd
49	¹¹³In	¹¹⁹In
50	¹¹⁴Sn	¹¹⁹Sn
51	¹¹⁵Sb	¹¹⁹Sb
52	¹¹⁶Te	¹¹⁹Te
53	¹¹⁷I	¹¹⁹I
54	¹¹⁸Xe	¹¹⁹Xe
55	¹¹⁹Cs	¹¹⁹Cs
56	¹²⁰Ba	¹¹⁹Ba
57	¹²¹La	¹¹⁹La
58	¹²²Ce	¹¹⁹Ce
59	¹²³Pr
60	¹²⁴Nd