Terbium-139

Properties and data of the isotope ¹³⁹Tb.

Content

General data

Name of the isotope:Terbium-139; Tb-139Symbol:¹³⁹Tb or 13965TbMass number A:139 (= number of nucleons)Atomic number Z:65 (= number of protons)Neutrons N:74Isotopic mass:138.94833(32) u (atomic weight of Terbium-139)Nuclide mass:138.9126753 u (calculated nuclear mass without electrons)Mass excess:-48.13029 MeVMass defect:1.201500864 u (per nucleus)Nuclear binding energy:1119.19084581 MeV (per nucleus)
8.0517327 MeV (average binding energy per nucleon)Separation energy:S_N = 12.53(42) MeV (first neutron)Half-life:1.6(2) sDecay constant λ:0.43321698784997 s^-1Specific activity α:1.890502698369 × 10⁺²¹ Bq g^-1
51094667523.503 Ci g^-1Spin and parity:
(nuclear angular momentum)Year of discovery:1999

Radioactive Decay

Half-life T_½ = 1.6(2) s.

Decay mode	Daughter	Probability	Decay energy
EE/β⁺	¹³⁹Gd	> 0 %	9.50(36) MeV
EE, p	¹³⁸Eu	?
p	¹³⁸Gd	?

Parent Nuclides

Direct parent isotope is: ¹³⁹Dy.

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 74) and isobaric (same nucleon number A = 139) with Terbium-139. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 74	Isobar A = 139
41	¹¹⁵Nb
42	¹¹⁶Mo
43	¹¹⁷Tc
44	¹¹⁸Ru
45	¹¹⁹Rh
46	¹²⁰Pd
47	¹²¹Ag
48	¹²²Cd
49	¹²³In
50	¹²⁴Sn	¹³⁹Sn
51	¹²⁵Sb	¹³⁹Sb
52	¹²⁶Te	¹³⁹Te
53	¹²⁷I	¹³⁹I
54	¹²⁸Xe	¹³⁹Xe
55	¹²⁹Cs	¹³⁹Cs
56	¹³⁰Ba	¹³⁹Ba
57	¹³¹La	¹³⁹La
58	¹³²Ce	¹³⁹Ce
59	¹³³Pr	¹³⁹Pr
60	¹³⁴Nd	¹³⁹Nd
61	¹³⁵Pm	¹³⁹Pm
62	¹³⁶Sm	¹³⁹Sm
63	¹³⁷Eu	¹³⁹Eu
64	¹³⁸Gd	¹³⁹Gd
65	¹³⁹Tb	¹³⁹Tb
66	¹⁴⁰Dy	¹³⁹Dy
67	¹⁴¹Ho