Molybdenum-93

Properties and data of the isotope ⁹³Mo.

Contents

General Data

Radioactive Decay

Parent Nuclides

Isotones und Isobares

Literature

Molybdenum-93 is a radioisotope of the chemical element molybdenum, which has 51 neutrons in its atomic nucleus in addition to the element-specific 42 protons, resulting in a mass number of 93. The very short-lived, only artificially produced, unstable and thus radioactive nuclide has no practical applications; however, the nuclide ⁹³Mo occurs as a decay product in various processes (e.g. neutron activation of Mo and in proton-irradiated Nb components through (p,n) reactions) in nuclear facilities such as nuclear power plants. The long-lived radionuclide thus ends up in the nuclear waste and must therefore be measured or separated in order to characterize decommissioning waste.

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

General data

Name of the isotope:Molybdenum-93; Mo-93Symbol:⁹³Mo or 9342MoMass number A:93 (= number of nucleons)Atomic number Z:42 (= number of protons)Neutrons N:51Nucleon pairing (Z - N):even - oddNuclear ratio (N/Z ratio):1.2142857142857 (= neutron-proton ratio)Neutron excess (N-Z):9Isotopic mass:92.90680877(19) u (atomic weight of Molybdenum-93)Nuclide mass:92.8837695 u (calculated nuclear mass without electrons)Mass excess:-86.80707 MeVMass defect:0.86375329000001 u (per nucleus)Nuclear binding energy:804.58100712 MeV (per nucleus)
8.65140868 MeV (average binding energy per nucleon)Separation energy:S_N = 8.06981(9) MeV (first neutron)
S_P = 7.6427(18) MeV (first proton)Half-life:4839(63) aDecay constant λ:4.542168404564 × 10^-12 s^-1Specific activity α:29732149936.786 Bq g^-1
0.80357161991314 Ci g^-1Spin and parity:
(nuclear angular momentum)5/2+Year of discovery:1946

Radioactive Decay

The half-life of molybdenum-93 was first directly determined in 2021 [2] and adopted here; until then, t_1/2 was given as 4000 ± 800 years.

The direct radioactive decay product after electron capture (EC) of Mo-93 is the stable isotope Niobium-93.

Half-life T_½ = 4839(63) a respectively 1.52602704 × 10¹¹ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
EC	⁹³Nb	100 %	0.4058(15) MeV

Parent Nuclides

Direct parent isotope is: ⁹³Tc.

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
^93mMo	2424.95(4) keV	6.85(7) h	21/2+

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 51) and isobaric (same nucleon number A = 93) with Molybdenum-93. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 51	Isobar A = 93
28	⁷⁹Ni
29	⁸⁰Cu
30	⁸¹Zn
31	⁸²Ga
32	⁸³Ge
33	⁸⁴As
34	⁸⁵Se	⁹³Se
35	⁸⁶Br	⁹³Br
36	⁸⁷Kr	⁹³Kr
37	⁸⁸Rb	⁹³Rb
38	⁸⁹Sr	⁹³Sr
39	⁹⁰Y	⁹³Y
40	⁹¹Zr	⁹³Zr
41	⁹²Nb	⁹³Nb
42	⁹³Mo	⁹³Mo
43	⁹⁴Tc	⁹³Tc
44	⁹⁵Ru	⁹³Ru
45	⁹⁶Rh	⁹³Rh
46	⁹⁷Pd	⁹³Pd
47	⁹⁸Ag	⁹³Ag
48	⁹⁹Cd
49	¹⁰⁰In
50	¹⁰¹Sn

External data and identifiers

Adopted Levels, Gammas:NuDat 93Mo

Literature and References

[1] - Szabolcs Osváth, Jixin Qiao, Xiaolin Hou:
Preparation of ⁹³Mo solution using proton irradiated Nb.
In: Journal of Radioanalytical and Nuclear Chemistry, 322, (2019), DOI 10.1007/s10967-019-06758-5.

[2] - I. Kajan, S. Heinitz, K. Kossert, P. Sprung, R. Dressler, D. Schumann:
First direct determination of the ⁹³Mo half-life.
In: Scientific Reports, 11, 19788, (2021), DOI 10.1038/s41598-021-99253-5.