Promethium-139

Properties and data of the isotope ¹³⁹Pm.

Content

General data

Name of the isotope:Promethium-139; Pm-139Symbol:¹³⁹Pm or 13961PmMass number A:139 (= number of nucleons)Atomic number Z:61 (= number of protons)Neutrons N:78Isotopic mass:138.91680(15) u (atomic weight of Promethium-139)Nuclide mass:138.8833392 u (calculated nuclear mass without electrons)Mass excess:-77.5003 MeVMass defect:1.2363904 u (per nucleus)Nuclear binding energy:1151.69023926 MeV (per nucleus)
8.28554129 MeV (average binding energy per nucleon)Separation energy:S_N = 10.63(3) MeV (first neutron)
S_P = 2.771(18) MeV (first proton)Half-life:4.15(5) minDecay constant λ:0.0027837236167066 s^-1Specific activity α:1.21478085035 × 10⁺¹⁹ Bq g^-1
328319148.74541 Ci g^-1Spin and parity:
(nuclear angular momentum)(5/2)+Year of discovery:1967

Radioactive Decay

Half-life T_½ = 4.15(5) min (minutes) respectively 2.49 × 10² seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
EE/β⁺	¹³⁹Nd	100%	4.51(3) MeV

Parent Nuclides

Direct parent isotope is: ¹³⁹Sm.

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
^139mPm	188.7(3) keV	0.18(2) s	(11/2)-

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 78) and isobaric (same nucleon number A = 139) with Promethium-139. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 78	Isobar A = 139
43	¹²¹Tc
44	¹²²Ru
45	¹²³Rh
46	¹²⁴Pd
47	¹²⁵Ag
48	¹²⁶Cd
49	¹²⁷In
50	¹²⁸Sn	¹³⁹Sn
51	¹²⁹Sb	¹³⁹Sb
52	¹³⁰Te	¹³⁹Te
53	¹³¹I	¹³⁹I
54	¹³²Xe	¹³⁹Xe
55	¹³³Cs	¹³⁹Cs
56	¹³⁴Ba	¹³⁹Ba
57	¹³⁵La	¹³⁹La
58	¹³⁶Ce	¹³⁹Ce
59	¹³⁷Pr	¹³⁹Pr
60	¹³⁸Nd	¹³⁹Nd
61	¹³⁹Pm	¹³⁹Pm
62	¹⁴⁰Sm	¹³⁹Sm
63	¹⁴¹Eu	¹³⁹Eu
64	¹⁴²Gd	¹³⁹Gd
65	¹⁴³Tb	¹³⁹Tb
66	¹⁴⁴Dy	¹³⁹Dy
67	¹⁴⁵Ho
68	¹⁴⁶Er
69	¹⁴⁷Tm
70	¹⁴⁸Yb
71	¹⁴⁹Lu