Promethium-139m

Properties and data of the isotope ^139mPm.

Contents

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

General data

Name of the isotope:Promethium-139m; Pm-139mSymbol:^139mPm or 139m61PmMass number A:139 (= number of nucleons)Atomic number Z:61 (= number of protons)Neutrons N:78Excitation energy:188.7(3) keVIsotopic mass:138.91680(15) u (atomic weight of Promethium-139m)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)Half-life:0.18(2) sDecay constant λ:3.8508176697775 s^-1Specific activity α:1.680446842995 × 10⁺²² Bq g^-1
454174822431.14 Ci g^-1Spin and parity:
(nuclear angular momentum)(11/2)-

Radioactive Decay

Half-life T_½ = 0.18(2) s respectively 1.8 × 10^-1 seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
EC/β⁺	¹³⁹Nd	< 0.05 %
Iso	¹³⁹Pm	& gt; 99.95 %

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
¹³⁹Pm		4.15(5) min	(5/2)+

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-139m. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	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