Lead-191m

Properties and data of the isotope ^191mPb.

Contents

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

General data

Name of the isotope:Lead-191m; Pb-191mSymbol:^191mPb or 191m82PbMass number A:191 (= number of nucleons)Atomic number Z:82 (= number of protons)Neutrons N:109Nucleon pairing (Z - N):even - oddNuclear ratio (N/Z ratio):1.3292682926829 (= neutron-proton ratio)Neutron excess (N-Z):27Excitation energy:+x keVIsotopic mass:190.97828(4) u (atomic weight of Lead-191m)Nuclide mass:190.9333016 u (calculated nuclear mass without electrons)Mass excess:-20.23205 MeVMass defect:1.607848468 u (per nucleus)Nuclear binding energy:1497.70120085 MeV (per nucleus)
7.84136754 MeV (average binding energy per nucleon)Half-life:2.18(8) minDecay constant λ:0.0052992903712534 s^-1Specific activity α:1.679635424915 × 10⁺¹⁹ Bq g^-1
453955520.24743 Ci g^-1Spin and parity:
(nuclear angular momentum)(13/2+)Magnetic dipole moment:μ(μ_N) = -1.176(8)Quadrupole moment Q:0.085(5) barn (100 fm²)Nuclear g-factor:g_l = -0.18092307692308

Radioactive Decay

Half-life T_½ = 2.18(8) min (minutes) respectively 1.308 × 10² seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
β⁺	¹⁹¹Tl	99.98 %
α	¹⁸⁷Hg	0.02 %

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
¹⁹¹Pb		1.33(8) min	(3/2-)

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 109) and isobaric (same nucleon number A = 191) with Lead-191m. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 109	Isobar A = 191
68	¹⁷⁷Er
69	¹⁷⁸Tm
70	¹⁷⁹Yb
71	¹⁸⁰Lu
72	¹⁸¹Hf
73	¹⁸²Ta	¹⁹¹Ta
74	¹⁸³W	¹⁹¹W
75	¹⁸⁴Re	¹⁹¹Re
76	¹⁸⁵Os	¹⁹¹Os
77	¹⁸⁶Ir	¹⁹¹Ir
78	¹⁸⁷Pt	¹⁹¹Pt
79	¹⁸⁸Au	¹⁹¹Au
80	¹⁸⁹Hg	¹⁹¹Hg
81	¹⁹⁰Tl	¹⁹¹Tl
82	¹⁹¹Pb	¹⁹¹Pb
83	¹⁹²Bi	¹⁹¹Bi
84	¹⁹³Po	¹⁹¹Po
85	¹⁹⁴At	¹⁹¹At
86	¹⁹⁵Rn