Promethium-140

Properties and data of the isotope ¹⁴⁰Pm.

Content

General data

Name of the isotope:Promethium-140; Pm-140Symbol:¹⁴⁰Pm or 14061PmMass number A:140 (= number of nucleons)Atomic number Z:61 (= number of protons)Neutrons N:79Isotopic mass:139.916034(26) u (atomic weight of Promethium-140)Nuclide mass:139.8825732 u (calculated nuclear mass without electrons)Mass excess:-78.21383 MeVMass defect:1.245821316 u (per nucleus)Nuclear binding energy:1160.47508093 MeV (per nucleus)
8.28910772 MeV (average binding energy per nucleon)Separation energy:S_N = 8.785(28) MeV (first neutron)
S_P = 3.49(4) MeV (first proton)Half-life:9.2(2) sDecay constant λ:0.075342084843472 s^-1Specific activity α:3.264177320925 × 10⁺²⁰ Bq g^-1
8822100867.3673 Ci g^-1Spin and parity:
(nuclear angular momentum)1+Year of discovery:1966

Radioactive Decay

Half-life T_½ = 9.2(2) s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
EE/β⁺	¹⁴⁰Nd	100 %	6.045(24) MeV

Parent Nuclides

Direct parent isotope is: ¹⁴⁰Sm.

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
^140mPm	+x keV	5.95(5) min	8-

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 79) and isobaric (same nucleon number A = 140) with Promethium-140. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 79	Isobar A = 140
44	¹²³Ru
45	¹²⁴Rh
46	¹²⁵Pd
47	¹²⁶Ag
48	¹²⁷Cd
49	¹²⁸In
50	¹²⁹Sn
51	¹³⁰Sb	¹⁴⁰Sb
52	¹³¹Te	¹⁴⁰Te
53	¹³²I	¹⁴⁰I
54	¹³³Xe	¹⁴⁰Xe
55	¹³⁴Cs	¹⁴⁰Cs
56	¹³⁵Ba	¹⁴⁰Ba
57	¹³⁶La	¹⁴⁰La
58	¹³⁷Ce	¹⁴⁰Ce
59	¹³⁸Pr	¹⁴⁰Pr
60	¹³⁹Nd	¹⁴⁰Nd
61	¹⁴⁰Pm	¹⁴⁰Pm
62	¹⁴¹Sm	¹⁴⁰Sm
63	¹⁴²Eu	¹⁴⁰Eu
64	¹⁴³Gd	¹⁴⁰Gd
65	¹⁴⁴Tb	¹⁴⁰Tb
66	¹⁴⁵Dy	¹⁴⁰Dy
67	¹⁴⁶Ho	¹⁴⁰Ho
68	¹⁴⁷Er
69	¹⁴⁸Tm
70	¹⁴⁹Yb
71	¹⁵⁰Lu