Barium-137m

Properties and data of the isotope ^137mBa.

Contents

General Data

Radioactive Decay

Parent Nuclides

Isotones und Isobares

Literature

See also: List of individual Barium isotopes (and general data sources).

General data

Name of the isotope:Barium-137m; Ba-137mSymbol:^137mBa or 137m56BaMass number A:137 (= number of nucleons)Atomic number Z:56 (= number of protons)Neutrons N:81Nucleon pairing (Z - N):even - oddNuclear ratio (N/Z ratio):1.4464285714286 (= neutron-proton ratio)Neutron excess (N-Z):25Excitation energy:661.659(3) keVIsotopic mass:136.905827(2) u (atomic weight of Barium-137m)Nuclide mass:136.8751086 u (calculated nuclear mass without electrons)Mass excess:-87.72158 MeVMass defect:1.234232988 u (per nucleus)Nuclear binding energy:1149.68062292 MeV (per nucleus)
8.39182936 MeV (average binding energy per nucleon)Half-life:2.552(1) minDecay constant λ:0.004526823279519 s^-1Specific activity α:2.004497605684 × 10⁺¹⁹ Bq g^-1
541756109.64435 Ci g^-1Spin and parity:
(nuclear angular momentum)11/2-Magnetic dipole moment:μ(μ_N) = -0.99(3)Quadrupole moment Q:+0.78(9) barn (100 fm²)Nuclear g-factor:g_l = -0.18

Radioactive Decay

Half-life T_½ = 2.552(1) min (minutes) respectively 1.5312 × 10² seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
Iso	¹³⁷Ba	100 %

Parent Nuclides

Direct parent isotope is: ¹³⁷Cs.

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
¹³⁷Ba		stable	3/2+
^137m2Ba	2349.1(5) keV	0.59(10) μs	(17/2-)

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 81) and isobaric (same nucleon number A = 137) with Barium-137m. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 81	Isobar A = 137
45	¹²⁶Rh
46	¹²⁷Pd
47	¹²⁸Ag
48	¹²⁹Cd
49	¹³⁰In	¹³⁷In
50	¹³¹Sn	¹³⁷Sn
51	¹³²Sb	¹³⁷Sb
52	¹³³Te	¹³⁷Te
53	¹³⁴I	¹³⁷I
54	¹³⁵Xe	¹³⁷Xe
55	¹³⁶Cs	¹³⁷Cs
56	¹³⁷Ba	¹³⁷Ba
57	¹³⁸La	¹³⁷La
58	¹³⁹Ce	¹³⁷Ce
59	¹⁴⁰Pr	¹³⁷Pr
60	¹⁴¹Nd	¹³⁷Nd
61	¹⁴²Pm	¹³⁷Pm
62	¹⁴³Sm	¹³⁷Sm
63	¹⁴⁴Eu	¹³⁷Eu
64	¹⁴⁵Gd	¹³⁷Gd
65	¹⁴⁶Tb	¹³⁷Tb
66	¹⁴⁷Dy
67	¹⁴⁸Ho
68	¹⁴⁹Er
69	¹⁵⁰Tm
70	¹⁵¹Yb
71	¹⁵²Lu
72	¹⁵³Hf

External data and identifiers

Adopted Levels, Gammas:NuDat 137Ba

Literature and References

[1] - C. Walz, H. Scheit, N. Pietralla, T. Aumann, R. Lefol, V. Yu. Ponomarev :
Observation of the competitive double-gamma nuclear decay.
In: Nature, (2015), DOI 10.1038/nature15543.

[2] - P.-A. Söderström, L. Capponi, E. Açıksöz, T. Otsuka, N. Tsoneva, Y. Tsunoda, D. L. Balabanski, N. Pietralla, G. L. Guardo, D. Lattuada, H. Lenske, C. Matei, D. Nichita, A. Pappalardo, T. Petruse:
Electromagnetic character of the competitive γγ/γ-decay from ^137mBa.
In: Nature Communications, (2020), DOI 10.1038/s41467-020-16787-4.