Polonium-201

Properties and data of the isotope ²⁰¹Po.

Contents

General Data

Radioactive Decay

Parent Nuclides

Isotones und Isobares

Literature

Polonium-201 is a radioisotope of the chemical element polonium, which has 117 neutrons in its atomic nucleus in addition to the element-specific 84 protons; the sum of the number of these atomic nucleus building blocks results in a mass number of 201. The very short-lived, only artificially produced, unstable and thus radioactive nuclide has no practical significance; the study of ²⁰¹Po is exclusively for academic purposes and experimental research.

A report on the first observation of the nuclide Po-201 was published in 1951 [1].

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

General data

Name of the isotope:Polonium-201; Po-201Symbol:²⁰¹Po or 20184PoMass 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):33Isotopic mass:200.982264(5) u (atomic weight of Polonium-201)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)Separation energy:S_N = 7.651(9) MeV (first neutron)
S_P = 3.440(23) MeV (first proton)Half-life:15.6(1) minDecay constant λ:0.00074054185957259 s^-1Specific activity α:2.229823695512 × 10⁺¹⁸ Bq g^-1
60265505.28413 Ci g^-1Spin and parity:
(nuclear angular momentum)3/2-Magnetic dipole moment:μ(μ_N) = 0.984(70)Gyromagnetic ratio γ:+10(10) · 10⁷ rad T^-1 s^-1Nuclear g-factor:g_l = 0.656Year of discovery:1951

Radioactive Decay

Half-life T_½ = 15.6(1) min (minutes) respectively 9.36 × 10² seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
α	¹⁹⁷Pb	1.13(3) %	5.7993(17) MeV
EC/β⁺	²⁰¹Bi	98.87(3) %	4.908(13) MeV

Parent Nuclides

Direct parent isotopes are: ²⁰⁵Rn, ²⁰¹At.

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
^201mPo	424.41(22) keV	8.96(12) min	13/2+

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-201. 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

External data and identifiers

Adopted Levels, Gammas:NuDat 201Po

Literature and References

[1] - D. G. Karraker, A. Ghiorso, D. H. Templeton:
Alpha-Decay Energies of Polonium Isotopes.
In: Physical Review, 83, 390, (1951), DOI 10.1103/PhysRev.83.390.