Thallium-207m

Properties and data of the isotope ^207mTl.

Contents

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

General data

Name of the isotope:Thallium-207m; Tl-207mSymbol:^207mTl or 207m81TlMass number A:207 (= number of nucleons)Atomic number Z:81 (= number of protons)Neutrons N:126Nucleon pairing (Z - N):odd - evenNuclear ratio (N/Z ratio):1.5555555555556 (= neutron-proton ratio)Neutron excess (N-Z):45Excitation energy:1348.18(16) keVIsotopic mass:206.977419(6) u (atomic weight of Thallium-207m)Nuclide mass:206.932989 u (calculated nuclear mass without electrons)Mass excess:-21.03407 MeVMass defect:1.748188008 u (per nucleus)Nuclear binding energy:1628.42664032 MeV (per nucleus)
7.86679536 MeV (average binding energy per nucleon)Half-life:1.33(11) sDecay constant λ:0.52116329365409 s^-1Specific activity α:1.523552798744 × 10⁺²¹ Bq g^-1
41177102668.768 Ci g^-1Spin and parity:
(nuclear angular momentum)11/2-

Radioactive Decay

Half-life T_½ = 1.33(11) s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
Iso	²⁰⁷Tl	100 %

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
²⁰⁷Tl		4.77(3) min	1/2+

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 126) and isobaric (same nucleon number A = 207) with Thallium-207m. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 126	Isobar A = 207
76	²⁰²Os
77	²⁰³Ir
78	²⁰⁴Pt	²⁰⁷Pt
79	²⁰⁵Au	²⁰⁷Au
80	²⁰⁶Hg	²⁰⁷Hg
81	²⁰⁷Tl	²⁰⁷Tl
82	²⁰⁸Pb	²⁰⁷Pb
83	²⁰⁹Bi	²⁰⁷Bi
84	²¹⁰Po	²⁰⁷Po
85	²¹¹At	²⁰⁷At
86	²¹²Rn	²⁰⁷Rn
87	²¹³Fr	²⁰⁷Fr
88	²¹⁴Ra	²⁰⁷Ra
89	²¹⁵Ac	²⁰⁷Ac
90	²¹⁶Th	²⁰⁷Th
91	²¹⁷Pa
92	²¹⁸U
93	²¹⁹Np