Polonium-211m1

Properties and data of the isotope ²¹¹Po.

Content

General data

Name of the isotope:Polonium-211m1; Po-211m1Symbol:²¹¹Po or 21184PoMass number A:211 (= number of nucleons)Atomic number Z:84 (= number of protons)Neutrons N:127Isotopic mass:210.9866531(13) u (atomic weight of Polonium-211m1)
Excitation energy: 1462(5) keVNuclide mass:210.9405778 u (calculated nuclear mass without electrons)Mass excess:-12.43256 MeVMass defect:1.77109392 u (per nucleus)Nuclear binding energy:1649.76335992 MeV (per nucleus)
7.8187837 MeV (average binding energy per nucleon)Half-life:25.2(6) sDecay constant λ:0.027505840498411 s^-1Specific activity α:7.887811712018 × 10⁺¹⁹ Bq g^-1
2131841003.2481 Ci g^-1Spin and parity:
(nuclear angular momentum)(25/2+)

Radioactive Decay

Half-life T_½ = 25.2(6) s respectively 2.52 × 10¹ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
α	²⁰⁷Pb	99.984(4) %
Iso	²¹¹Po	0.016(4) %

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
²¹¹Po		0.516(3) s	9/2+
^211m2Po	2135(5) keV	243(21) ns	(31/2-)
^211m3Po	4872(6) keV	2.8(7) μs	(43/2+)

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 127) and isobaric (same nucleon number A = 211) with Polonium-211m1. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 127	Isobar A = 211
76	²⁰³Os
77	²⁰⁴Ir
78	²⁰⁵Pt
79	²⁰⁶Au
80	²⁰⁷Hg	²¹¹Hg
81	²⁰⁸Tl	²¹¹Tl
82	²⁰⁹Pb	²¹¹Pb
83	²¹⁰Bi	²¹¹Bi
84	²¹¹Po	²¹¹Po
85	²¹²At	²¹¹At
86	²¹³Rn	²¹¹Rn
87	²¹⁴Fr	²¹¹Fr
88	²¹⁵Ra	²¹¹Ra
89	²¹⁶Ac	²¹¹Ac
90	²¹⁷Th	²¹¹Th
91	²¹⁸Pa
92	²¹⁹U