Potassium-38m1

Properties and data of the isotope ^38m1K.

Contents

Potassium-38m1 is an excited nuclear state of the nuclide ³⁸K, characterized by a defined excitation energy (130.15 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 primarily via radioactive EE/β+ decay and less frequently via an isomeric transition to K-28 in the ground state, with a half-life of approximately 924 milliseconds.

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

General data

Name of the isotope:Potassium-38m1; K-38m1Symbol:^38m1K or 38m119KMass number A:38 (= number of nucleons)Atomic number Z:19 (= number of protons)Neutrons N:19Nucleon pairing (Z - N):odd - oddNuclear ratio (N/Z ratio):1 (= neutron-proton ratio)Neutron excess (N-Z):0Excitation energy:130.15(4) keVIsotopic mass:37.96908111(21) u (atomic weight of Potassium-38m1)Nuclide mass:37.9586583 u (calculated nuclear mass without electrons)Mass excess:-28.80076 MeVMass defect:0.344227902 u (per nucleus)Nuclear binding energy:320.64622535 MeV (per nucleus)
8.43805856 MeV (average binding energy per nucleon)Half-life:924.4(3) msDecay constant λ:0.7498346825616 s^-1Specific activity α:1.220435156770 × 10⁺²² Bq g^-1
329847339667.78 Ci g^-1Spin and parity:
(nuclear angular momentum)0+Isobaric spin: 1Year of discovery:1953

Radioactive Decay

Half-life T_½ = 924.4(3) ms respectively 9.244 × 10^-1 seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
EC/β⁺	³⁸Ar	99.9670(43) %	6.742 MeV
Iso	³⁸K	0.0330(43) %

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
³⁸K		7.651(19) min	3+
^38m2K	3458.10(17) keV	21.95(11) μs	(7)+

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 19) and isobaric (same nucleon number A = 38) with Potassium-38m1. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 19	Isobar A = 38
8	²⁷O
9	²⁸F
10	²⁹Ne
11	³⁰Na	³⁸Na
12	³¹Mg	³⁸Mg
13	³²Al	³⁸Al
14	³³Si	³⁸Si
15	³⁴P	³⁸P
16	³⁵S	³⁸S
17	³⁶Cl	³⁸Cl
18	³⁷Ar	³⁸Ar
19	³⁸K	³⁸K
20	³⁹Ca	³⁸Ca
21	⁴⁰Sc	³⁸Sc
22	⁴¹Ti	³⁸Ti
23	⁴²V
24	⁴³Cr
25	⁴⁴Mn
26	⁴⁵Fe
27	⁴⁶Co