Manganese-50m

Properties and data of the isotope ^50mMn.

Contents

Manganese-50m is an excited nuclear state of the nuclide ⁵⁰Mn, characterized by a defined excitation energy of 225.28 keV. Its spin and parity quantum numbers differ from those of the ground state (gs). Simultaneously, this metastable nuclear isomer possesses an independent, experimentally measurable lifetime: The decay occurs via an EE β⁺ decay to chromium-50 with a half-life of about 1.75 minutes.

Manganese-50m was first mentioned in a doctoral thesis from 1962 [D. C. Sutton, Half-Lives of and Isomerism in V⁴⁶, Mn⁵⁰, Co⁵⁴ and Cu⁵⁸, Princeton University, (1962)].

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

General data

Name of the isotope:Manganese-50m; Mn-50mSymbol:^50mMn or 50m25MnMass number A:50 (= number of nucleons)Atomic number Z:25 (= number of protons)Neutrons N:25Nucleon pairing (Z - N):odd - oddNuclear ratio (N/Z ratio):1 (= neutron-proton ratio)Neutron excess (N-Z):0Excitation energy:225.28(9) keVIsotopic mass:49.95423816(12) u (atomic weight of Manganese-50m)Nuclide mass:49.940524 u (calculated nuclear mass without electrons)Mass excess:-42.62688 MeVMass defect:0.45801054 u (per nucleus)Nuclear binding energy:426.63406995 MeV (per nucleus)
8.5326814 MeV (average binding energy per nucleon)Half-life:1.75(3) minDecay constant λ:0.0066014017196185 s^-1Specific activity α:7.958197709174 × 10⁺¹⁹ Bq g^-1
2150864245.7229 Ci g^-1Spin and parity:
(nuclear angular momentum)5+Isobaric spin: 0Magnetic dipole moment:μ(μ_N) = +2.76(1)Quadrupole moment Q:+0.83(12) barn (100 fm²)Nuclear g-factor:g_l = 0.552Year of discovery:1962

Radioactive Decay

Half-life T_½ = 1.75(3) min (minutes) respectively 1.05 × 10² seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
EC β⁺	⁵⁰Cr	100 %	7.887 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
⁵⁰Mn		283.19(10) ms	0+

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 25) and isobaric (same nucleon number A = 50) with Manganese-50m. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 25	Isobar A = 50
11	³⁶Na
12	³⁷Mg
13	³⁸Al
14	³⁹Si
15	⁴⁰P
16	⁴¹S
17	⁴²Cl	⁵⁰Cl
18	⁴³Ar	⁵⁰Ar
19	⁴⁴K	⁵⁰K
20	⁴⁵Ca	⁵⁰Ca
21	⁴⁶Sc	⁵⁰Sc
22	⁴⁷Ti	⁵⁰Ti
23	⁴⁸V	⁵⁰V
24	⁴⁹Cr	⁵⁰Cr
25	⁵⁰Mn	⁵⁰Mn
26	⁵¹Fe	⁵⁰Fe
27	⁵²Co	⁵⁰Co
28	⁵³Ni	⁵⁰Ni
29	⁵⁴Cu
30	⁵⁵Zn