Promethium-161

Properties and data of the isotope ¹⁶¹Pm.

Contents

General data

Name of the isotope:Promethium-161; Pm-161Symbol:¹⁶¹Pm or 16161PmMass number A:161 (= number of nucleons)Atomic number Z:61 (= number of protons)Neutrons N:100Isotopic mass:160.94607(32) u (atomic weight of Promethium-161)Nuclide mass:160.9126092 u (calculated nuclear mass without electrons)Mass excess:-50.23547 MeVMass defect:1.397748552 u (per nucleus)Nuclear binding energy:1301.9943897 MeV (per nucleus)
8.08692168 MeV (average binding energy per nucleon)Separation energy:S_N = 5.30(36) MeV (first neutron)
S_P = 10.39(42) MeV (first proton)Half-life:1.05(15) sDecay constant λ:0.66014017196185 s^-1Specific activity α:2.484660689285 × 10⁺²¹ Bq g^-1
67152991602.316 Ci g^-1Spin and parity:
(nuclear angular momentum)(5/2-)Year of discovery:2012

Radioactive Decay

Half-life T_½ = 1.05(15) s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
β^-	¹⁶¹Sm	100 %	6.44(30) MeV
β^-, n	¹⁶⁰Sm	?	1.93(30) MeV

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 100) and isobaric (same nucleon number A = 161) with Promethium-161. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 100	Isobar A = 161
58	¹⁵⁸Ce
59	¹⁵⁹Pr
60	¹⁶⁰Nd	¹⁶¹Nd
61	¹⁶¹Pm	¹⁶¹Pm
62	¹⁶²Sm	¹⁶¹Sm
63	¹⁶³Eu	¹⁶¹Eu
64	¹⁶⁴Gd	¹⁶¹Gd
65	¹⁶⁵Tb	¹⁶¹Tb
66	¹⁶⁶Dy	¹⁶¹Dy
67	¹⁶⁷Ho	¹⁶¹Ho
68	¹⁶⁸Er	¹⁶¹Er
69	¹⁶⁹Tm	¹⁶¹Tm
70	¹⁷⁰Yb	¹⁶¹Yb
71	¹⁷¹Lu	¹⁶¹Lu
72	¹⁷²Hf	¹⁶¹Hf
73	¹⁷³Ta	¹⁶¹Ta
74	¹⁷⁴W	¹⁶¹W
75	¹⁷⁵Re	¹⁶¹Re
76	¹⁷⁶Os	¹⁶¹Os
77	¹⁷⁷Ir
78	¹⁷⁸Pt
79	¹⁷⁹Au
80	¹⁸⁰Hg
81	¹⁸¹Tl
82	¹⁸²Pb