Indium-121m

Properties and data of the isotope ^121mIn.

Contents

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

General data

Name of the isotope:Indium-121m; In-121mSymbol:^121mIn or 121m49InMass number A:121 (= number of nucleons)Atomic number Z:49 (= number of protons)Neutrons N:72Isotopic mass:120.907851(29) u (atomic weight of Indium-121m)
Excitation energy: 313.68(7) keVNuclide mass:120.8809721 u (calculated nuclear mass without electrons)Mass excess:-85.83624 MeVMass defect:1.09944952 u (per nucleus)Nuclear binding energy:1024.13063118 MeV (per nucleus)
8.46388951 MeV (average binding energy per nucleon)Half-life:3.88(10) minDecay constant λ:0.0029774363426114 s^-1Specific activity α:1.494211754725 × 10⁺¹⁹ Bq g^-1
403841014.79057 Ci g^-1Spin and parity:
(nuclear angular momentum)1/2-Magnetic dipole moment:μ(μ_N) = - 0.354(4)Nuclear g-factor:g_l = -0.708

Radioactive Decay

Half-life T_½ = 3.88(10) min (minutes) respectively 2.328 × 10² seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
β^-	¹²¹Sn	98.8(2) %
Iso	¹²¹In	1.2(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
¹²¹In		23.1(6) s	9/2+

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 72) and isobaric (same nucleon number A = 121) with Indium-121m. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 72	Isobar A = 121
40	¹¹²Zr
41	¹¹³Nb
42	¹¹⁴Mo
43	¹¹⁵Tc	¹²¹Tc
44	¹¹⁶Ru	¹²¹Ru
45	¹¹⁷Rh	¹²¹Rh
46	¹¹⁸Pd	¹²¹Pd
47	¹¹⁹Ag	¹²¹Ag
48	¹²⁰Cd	¹²¹Cd
49	¹²¹In	¹²¹In
50	¹²²Sn	¹²¹Sn
51	¹²³Sb	¹²¹Sb
52	¹²⁴Te	¹²¹Te
53	¹²⁵I	¹²¹I
54	¹²⁶Xe	¹²¹Xe
55	¹²⁷Cs	¹²¹Cs
56	¹²⁸Ba	¹²¹Ba
57	¹²⁹La	¹²¹La
58	¹³⁰Ce	¹²¹Ce
59	¹³¹Pr	¹²¹Pr
60	¹³²Nd
61	¹³³Pm
62	¹³⁴Sm
63	¹³⁵Eu
64	¹³⁶Gd
65	¹³⁷Tb
66	¹³⁸Dy