Potassium-50m

Properties and data of the isotope ^50mK.

Contents

Potassium-50m is an excited nuclear state of the nuclide ⁵⁰K, characterized by a defined excitation energy (172.0 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: decay occurs via an isomeric transition to K-50 in the ground state with a half-life of approximately 131 nanoseconds.

Potassium-50m was first mentioned in a doctoral thesis in 1999 [1].

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

General data

Name of the isotope:Potassium-50m; K-50mSymbol:^50mK or 50m19KMass number A:50 (= number of nucleons)Atomic number Z:19 (= number of protons)Neutrons N:31Nucleon pairing (Z - N):odd - oddNuclear ratio (N/Z ratio):1.6315789473684 (= neutron-proton ratio)Neutron excess (N-Z):12Excitation energy:172.0(4) keVIsotopic mass:49.972380(8) u (atomic weight of Potassium-50m)Nuclide mass:49.9619572 u (calculated nuclear mass without electrons)Mass excess:-25.72786 MeVMass defect:0.444908004 u (per nucleus)Nuclear binding energy:414.42913628 MeV (per nucleus)
8.28858273 MeV (average binding energy per nucleon)Half-life:131(40) nsDecay constant λ:5291199.8516026 s^-1Specific activity α:6.502928739679 × 10⁺²⁸ Bq g^-1
1.757548308021 × 10⁺¹⁸ Ci g^-1Spin and parity:
(nuclear angular momentum)(2-)Year of discovery:1999

Radioactive Decay

Half-life T_½ = 131(40) ns respectively 1.31 × 10^-7 seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
Iso	⁴⁰K	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
⁵⁰K		472(4) ms	0(-)

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 31) and isobaric (same nucleon number A = 50) with Potassium-50m. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 31	Isobar A = 50
15	⁴⁶P
16	⁴⁷S
17	⁴⁸Cl	⁵⁰Cl
18	⁴⁹Ar	⁵⁰Ar
19	⁵⁰K	⁵⁰K
20	⁵¹Ca	⁵⁰Ca
21	⁵²Sc	⁵⁰Sc
22	⁵³Ti	⁵⁰Ti
23	⁵⁴V	⁵⁰V
24	⁵⁵Cr	⁵⁰Cr
25	⁵⁶Mn	⁵⁰Mn
26	⁵⁷Fe	⁵⁰Fe
27	⁵⁸Co	⁵⁰Co
28	⁵⁹Ni	⁵⁰Ni
29	⁶⁰Cu
30	⁶¹Zn
31	⁶²Ga
32	⁶³Ge
33	⁶⁴As
34	⁶⁵Se
35	⁶⁶Br
36	⁶⁷Kr