Polonium-201m

Properties and data of the isotope ^201mPo.

Contents

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

General data

Name of the isotope:Polonium-201m; Po-201mSymbol:^201mPo or 201m84PoMass number A:201 (= number of nucleons)Atomic number Z:84 (= number of protons)Neutrons N:117Nucleon pairing (Z - N):even - oddNuclear ratio (N/Z ratio):1.3928571428571 (= neutron-proton ratio)Neutron excess (N-Z):33Excitation energy:424.41(22) keVIsotopic mass:200.982264(5) u (atomic weight of Polonium-201m)Nuclide mass:200.9361887 u (calculated nuclear mass without electrons)Mass excess:-16.52098 MeVMass defect:1.68883386 u (per nucleus)Nuclear binding energy:1573.13860759 MeV (per nucleus)
7.82656024 MeV (average binding energy per nucleon)Half-life:8.96(12) minDecay constant λ:0.001289336273363 s^-1Specific activity α:3.882282327008 × 10⁺¹⁸ Bq g^-1
104926549.37862 Ci g^-1Spin and parity:
(nuclear angular momentum)13/2+Magnetic dipole moment:μ(μ_N) = 1.002(70)Quadrupole moment Q:+1.26(20) barn (100 fm²)Nuclear g-factor:g_l = 0.15415384615385Year of discovery:1962

Radioactive Decay

Half-life T_½ = 8.96(12) min (minutes) respectively 5.376 × 10² seconds s.

Decay mode	Daughter	Probability
α	¹⁹⁷Pb	2.4(5) %
EC/β⁺	²⁰¹Bi	41.4(7) %
Iso	²⁰¹Po	56.2(12) %

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
²⁰¹Po		15.6(1) min	3/2-

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 117) and isobaric (same nucleon number A = 201) with Polonium-201m. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 117	Isobar A = 201
71	¹⁸⁸Lu
72	¹⁸⁹Hf
73	¹⁹⁰Ta
74	¹⁹¹W
75	¹⁹²Re
76	¹⁹³Os	²⁰¹Os
77	¹⁹⁴Ir	²⁰¹Ir
78	¹⁹⁵Pt	²⁰¹Pt
79	¹⁹⁶Au	²⁰¹Au
80	¹⁹⁷Hg	²⁰¹Hg
81	¹⁹⁸Tl	²⁰¹Tl
82	¹⁹⁹Pb	²⁰¹Pb
83	²⁰⁰Bi	²⁰¹Bi
84	²⁰¹Po	²⁰¹Po
85	²⁰²At	²⁰¹At
86	²⁰³Rn	²⁰¹Rn
87	²⁰⁴Fr	²⁰¹Fr
88	²⁰⁵Ra	²⁰¹Ra
89	²⁰⁶Ac
90	²⁰⁷Th