Thallium-189m

Properties and data of the isotope ^189mTl.

Contents

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

General data

Name of the isotope:Thallium-189m; Tl-189mSymbol:^189mTl or 189m81TlMass number A:189 (= number of nucleons)Atomic number Z:81 (= number of protons)Neutrons N:108Nucleon pairing (Z - N):odd - evenNuclear ratio (N/Z ratio):1.3333333333333 (= neutron-proton ratio)Neutron excess (N-Z):27Excitation energy:281(7) keVIsotopic mass:188.973574(9) u (atomic weight of Thallium-189m)Nuclide mass:188.929144 u (calculated nuclear mass without electrons)Mass excess:-24.61566 MeVMass defect:1.59606452 u (per nucleus)Nuclear binding energy:1486.72452399 MeV (per nucleus)
7.86626732 MeV (average binding energy per nucleon)Half-life:1.4(1) minDecay constant λ:0.0082517521495232 s^-1Specific activity α:2.643256052431 × 10⁺¹⁹ Bq g^-1
714393527.68422 Ci g^-1Spin and parity:
(nuclear angular momentum)(9/2-)Magnetic dipole moment:μ(μ_N) = + 3.878(6)Quadrupole moment Q:- 2.29(4) barn (100 fm²)Nuclear g-factor:g_l = 0.86177777777778

Radioactive Decay

Half-life T_½ = 1.4(1) min (minutes) respectively 8.4 × 10¹ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
EC/β⁺	¹⁸⁹Hg	98(2) %
Iso	¹⁸⁹Tl	2 % ?

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
¹⁸⁹Tl		2.3(2) min	(1/2+)

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 108) and isobaric (same nucleon number A = 189) with Thallium-189m. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 108	Isobar A = 189
66	¹⁷⁴Dy
67	¹⁷⁵Ho
68	¹⁷⁶Er
69	¹⁷⁷Tm
70	¹⁷⁸Yb
71	¹⁷⁹Lu
72	¹⁸⁰Hf	¹⁸⁹Hf
73	¹⁸¹Ta	¹⁸⁹Ta
74	¹⁸²W	¹⁸⁹W
75	¹⁸³Re	¹⁸⁹Re
76	¹⁸⁴Os	¹⁸⁹Os
77	¹⁸⁵Ir	¹⁸⁹Ir
78	¹⁸⁶Pt	¹⁸⁹Pt
79	¹⁸⁷Au	¹⁸⁹Au
80	¹⁸⁸Hg	¹⁸⁹Hg
81	¹⁸⁹Tl	¹⁸⁹Tl
82	¹⁹⁰Pb	¹⁸⁹Pb
83	¹⁹¹Bi	¹⁸⁹Bi
84	¹⁹²Po	¹⁸⁹Po
85	¹⁹³At	¹⁸⁹At
86	¹⁹⁴Rn