Chromium-45m

Properties and data of the isotope ^45mCr.

Contents

Chromium-45m is an excited nuclear state of the nuclide ⁴⁵Cr, characterized by a defined excitation energy of 107 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 Cr-45 in the ground state with a half-life of more than 80 microseconds.

Chromium-45m was first described in a 2011 article [1].

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

General data

Name of the isotope:Chromium-45m; Cr-45mSymbol:^45mCr or 45m24CrMass number A:45 (= number of nucleons)Atomic number Z:24 (= number of protons)Neutrons N:21Nucleon pairing (Z - N):even - oddNuclear ratio (N/Z ratio):0.875 (= neutron-proton ratio)Neutron excess (N-Z):-3Excitation energy:107(1) keVIsotopic mass:44.97905(4) u (atomic weight of Chromium-45m)Nuclide mass:44.9658844 u (calculated nuclear mass without electrons)Mass excess:-19.5148 MeVMass defect:0.390714004 u (per nucleus)Nuclear binding energy:363.94775044 MeV (per nucleus)
8.08772779 MeV (average binding energy per nucleon)Half-life:> 80 μsDecay constant λ:8664.3397569993 s^-1Specific activity α:1.160048369387 × 10⁺²⁶ Bq g^-1
3.135265863210 × 10⁺¹⁵ Ci g^-1Spin and parity:
(nuclear angular momentum)(3/2)Mirror nucleus:scandium-45mYear of discovery:2011

Radioactive Decay

Half-life T_½ = > 80 μs respectively 8 × 10^-5 seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
Iso	⁴⁵Cr	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
⁴⁵Cr		60.9(4) ms	(7/2-)

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 21) and isobaric (same nucleon number A = 45) with Chromium-45m. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 21	Isobar A = 45
9	³⁰F
10	³¹Ne
11	³²Na
12	³³Mg
13	³⁴Al
14	³⁵Si
15	³⁶P	⁴⁵P
16	³⁷S	⁴⁵S
17	³⁸Cl	⁴⁵Cl
18	³⁹Ar	⁴⁵Ar
19	⁴⁰K	⁴⁵K
20	⁴¹Ca	⁴⁵Ca
21	⁴²Sc	⁴⁵Sc
22	⁴³Ti	⁴⁵Ti
23	⁴⁴V	⁴⁵V
24	⁴⁵Cr	⁴⁵Cr
25	⁴⁶Mn	⁴⁵Mn
26	⁴⁷Fe	⁴⁵Fe
27	⁴⁸Co
28	⁴⁹Ni

External data and identifiers

Adopted Levels, Gammas:NuDat 45Cr

Literature and References

[1] - R. Hoischen, D. Rudolph, H. L. Ma et al.:
Isomeric mirror states as probes for effective charges in the lower pf shell.
In: Journal of Physics G, 38, 035104, (2011), DOI 10.1088/0954-3899/38/3/035104.