Indium-123m

Properties and data of the isotope ¹²³In.

Content

General data

Name of the isotope:Indium-123m; In-123mSymbol:¹²³In or 12349InMass number A:123 (= number of nucleons)Atomic number Z:49 (= number of protons)Neutrons N:74Isotopic mass:122.910434(21) u (atomic weight of Indium-123m)
Excitation energy: 327.21(4) keVNuclide mass:122.8835551 u (calculated nuclear mass without electrons)Mass excess:-83.43019 MeVMass defect:1.114196352 u (per nucleus)Nuclear binding energy:1037.86721671 MeV (per nucleus)
8.43794485 MeV (average binding energy per nucleon)Half-life:47.4(4) sDecay constant λ:0.014623358239661 s^-1Specific activity α:7.218354357750 × 10⁺¹⁹ Bq g^-1
1950906583.1758 Ci g^-1Spin and parity:
(nuclear angular momentum)(1/2)-Magnetic dipole moment:μ(μ_N) = - 0.399(4)Nuclear g-factor:g_l = -0.798

Radioactive Decay

Half-life T_½ = 47.4(4) s respectively 4.74 × 10¹ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
β^-	¹²³Sn	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
¹²³In		6.17(5) s	(9/2)+

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 74) and isobaric (same nucleon number A = 123) with Indium-123m. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 74	Isobar A = 123
41	¹¹⁵Nb
42	¹¹⁶Mo
43	¹¹⁷Tc
44	¹¹⁸Ru	¹²³Ru
45	¹¹⁹Rh	¹²³Rh
46	¹²⁰Pd	¹²³Pd
47	¹²¹Ag	¹²³Ag
48	¹²²Cd	¹²³Cd
49	¹²³In	¹²³In
50	¹²⁴Sn	¹²³Sn
51	¹²⁵Sb	¹²³Sb
52	¹²⁶Te	¹²³Te
53	¹²⁷I	¹²³I
54	¹²⁸Xe	¹²³Xe
55	¹²⁹Cs	¹²³Cs
56	¹³⁰Ba	¹²³Ba
57	¹³¹La	¹²³La
58	¹³²Ce	¹²³Ce
59	¹³³Pr	¹²³Pr
60	¹³⁴Nd
61	¹³⁵Pm
62	¹³⁶Sm
63	¹³⁷Eu
64	¹³⁸Gd
65	¹³⁹Tb
66	¹⁴⁰Dy
67	¹⁴¹Ho