Bismuth-201m

Properties and data of the isotope ²⁰¹Bi.

Content

General data

Name of the isotope:Bismuth-201m; Bi-201mSymbol:²⁰¹Bi or 20183BiMass number A:201 (= number of nucleons)Atomic number Z:83 (= number of protons)Neutrons N:118Isotopic mass:200.977009(16) u (atomic weight of Bismuth-201m)
Excitation energy: 846.35(18) keVNuclide mass:200.9314821 u (calculated nuclear mass without electrons)Mass excess:-21.41598 MeVMass defect:1.694928744 u (per nucleus)Nuclear binding energy:1578.81595546 MeV (per nucleus)
7.85480575 MeV (average binding energy per nucleon)Half-life:57.5(21) minDecay constant λ:0.00020091222624926 s^-1Specific activity α:6.049608634782 × 10⁺¹⁷ Bq g^-1
16350293.607521 Ci g^-1Spin and parity:
(nuclear angular momentum)1/2+

Radioactive Decay

Half-life T_½ = 57.5(21) min (minutes) respectively 3.450 × 10³ seconds s.

Decay mode	Daughter	Probability
EE/β⁺	²⁰¹Pb	≥ 91.1 %
α	¹⁹⁷Tl	ca. 0.3 %
Iso	²⁰¹Bi	≤ 8.6 %

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
²⁰¹Bi		103(3) min	9/2-

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 118) and isobaric (same nucleon number A = 201) with Bismuth-201m. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 118	Isobar A = 201
72	¹⁹⁰Hf
73	¹⁹¹Ta
74	¹⁹²W
75	¹⁹³Re
76	¹⁹⁴Os	²⁰¹Os
77	¹⁹⁵Ir	²⁰¹Ir
78	¹⁹⁶Pt	²⁰¹Pt
79	¹⁹⁷Au	²⁰¹Au
80	¹⁹⁸Hg	²⁰¹Hg
81	¹⁹⁹Tl	²⁰¹Tl
82	²⁰⁰Pb	²⁰¹Pb
83	²⁰¹Bi	²⁰¹Bi
84	²⁰²Po	²⁰¹Po
85	²⁰³At	²⁰¹At
86	²⁰⁴Rn	²⁰¹Rn
87	²⁰⁵Fr	²⁰¹Fr
88	²⁰⁶Ra	²⁰¹Ra
89	²⁰⁷Ac
90	²⁰⁸Th