Thallium-195m

Properties and data of the isotope ^195mTl.

Contents

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

General data

Name of the isotope:Thallium-195m; Tl-195mSymbol:^195mTl or 195m81TlMass number A:195 (= number of nucleons)Atomic number Z:81 (= number of protons)Neutrons N:114Nucleon pairing (Z - N):odd - evenNuclear ratio (N/Z ratio):1.4074074074074 (= neutron-proton ratio)Neutron excess (N-Z):33Excitation energy:482.63(17) keVIsotopic mass:194.969774(12) u (atomic weight of Thallium-195m)Nuclide mass:194.925344 u (calculated nuclear mass without electrons)Mass excess:-28.15534 MeVMass defect:1.651854016 u (per nucleus)Nuclear binding energy:1538.69210478 MeV (per nucleus)
7.89072874 MeV (average binding energy per nucleon)Half-life:3.6(4) sDecay constant λ:0.19254088348887 s^-1Specific activity α:5.976847018900 × 10⁺²⁰ Bq g^-1
16153640591.622 Ci g^-1Spin and parity:
(nuclear angular momentum)9/2-Magnetic dipole moment:μ(μ_N) = 3.869(39)Nuclear g-factor:g_l = 0.85977777777778

Radioactive Decay

Half-life T_½ = 3.6(4) s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
Iso	¹⁹⁵Tl	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
¹⁹⁵Tl		1.16(5) h	1/2+

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 114) and isobaric (same nucleon number A = 195) with Thallium-195m. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 114	Isobar A = 195
70	¹⁸⁴Yb
71	¹⁸⁵Lu
72	¹⁸⁶Hf
73	¹⁸⁷Ta
74	¹⁸⁸W	¹⁹⁵W
75	¹⁸⁹Re	¹⁹⁵Re
76	¹⁹⁰Os	¹⁹⁵Os
77	¹⁹¹Ir	¹⁹⁵Ir
78	¹⁹²Pt	¹⁹⁵Pt
79	¹⁹³Au	¹⁹⁵Au
80	¹⁹⁴Hg	¹⁹⁵Hg
81	¹⁹⁵Tl	¹⁹⁵Tl
82	¹⁹⁶Pb	¹⁹⁵Pb
83	¹⁹⁷Bi	¹⁹⁵Bi
84	¹⁹⁸Po	¹⁹⁵Po
85	¹⁹⁹At	¹⁹⁵At
86	²⁰⁰Rn	¹⁹⁵Rn
87	²⁰¹Fr
88	²⁰²Ra
89	²⁰³Ac