Thallium-177

Properties and data of the isotope ¹⁷⁷Tl.

Content

General data

Name of the isotope:Thallium-177; Tl-177Symbol:¹⁷⁷Tl or 17781TlMass number A:177 (= number of nucleons)Atomic number Z:81 (= number of protons)Neutrons N:96Isotopic mass:176.996414(23) u (atomic weight of Thallium-177)Nuclide mass:176.951984 u (calculated nuclear mass without electrons)Mass excess:-3.34034 MeVMass defect:1.469245528 u (per nucleus)Nuclear binding energy:1368.59339386 MeV (per nucleus)
7.73216607 MeV (average binding energy per nucleon)Separation energy:S_N = 11.99(8) MeV (first neutron)Half-life:18(5) msDecay constant λ:38.508176697775 s^-1Specific activity α:1.31762309280 × 10⁺²³ Bq g^-1
3561143494062.2 Ci g^-1Spin and parity:
(nuclear angular momentum)(1/2+)Year of discovery:1999

Radioactive Decay

Half-life T_½ = 18(5) ms respectively 1.8 × 10^-2 seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
α	¹⁷³Au	73(13) %	7.067(7) MeV
p	¹⁷⁶Hg	27(13) %	9.45 MeV

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
^177mTl	807(23) keV	230(40) μs	(11/2-)

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 96) and isobaric (same nucleon number A = 177) with Thallium-177. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 96	Isobar A = 177
55	¹⁵¹Cs
56	¹⁵²Ba
57	¹⁵³La
58	¹⁵⁴Ce
59	¹⁵⁵Pr
60	¹⁵⁶Nd
61	¹⁵⁷Pm
62	¹⁵⁸Sm
63	¹⁵⁹Eu
64	¹⁶⁰Gd
65	¹⁶¹Tb
66	¹⁶²Dy
67	¹⁶³Ho
68	¹⁶⁴Er	¹⁷⁷Er
69	¹⁶⁵Tm	¹⁷⁷Tm
70	¹⁶⁶Yb	¹⁷⁷Yb
71	¹⁶⁷Lu	¹⁷⁷Lu
72	¹⁶⁸Hf	¹⁷⁷Hf
73	¹⁶⁹Ta	¹⁷⁷Ta
74	¹⁷⁰W	¹⁷⁷W
75	¹⁷¹Re	¹⁷⁷Re
76	¹⁷²Os	¹⁷⁷Os
77	¹⁷³Ir	¹⁷⁷Ir
78	¹⁷⁴Pt	¹⁷⁷Pt
79	¹⁷⁵Au	¹⁷⁷Au
80	¹⁷⁶Hg	¹⁷⁷Hg
81	¹⁷⁷Tl	¹⁷⁷Tl
82	¹⁷⁸Pb