Selenium-81m

Properties and data of the isotope ^81mSe.

Contents

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

General data

Name of the isotope:Selenium-81m; Se-81mSymbol:^81mSe or 81m34SeMass number A:81 (= number of nucleons)Atomic number Z:34 (= number of protons)Neutrons N:47Isotopic mass:80.9179930(11) u (atomic weight of Selenium-81m)
Excitation energy: 103.00(6) keVNuclide mass:80.8993419 u (calculated nuclear mass without electrons)Mass excess:-76.38903 MeVMass defect:0.75530914000001 u (per nucleus)Nuclear binding energy:703.56593206 MeV (per nucleus)
8.68599916 MeV (average binding energy per nucleon)Half-life:57.28(2) minDecay constant λ:0.00020168388633611 s^-1Specific activity α:1.518210965869 × 10⁺¹⁸ Bq g^-1
41032728.807281 Ci g^-1Spin and parity:
(nuclear angular momentum)7/2+

Radioactive Decay

Half-life T_½ = 57.28(2) min (minutes) respectively 3.4368 × 10³ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
β^-	⁸¹Br	0.051(14) %
Iso	⁸¹Se	99.949(14) %

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
⁸¹Se		18.45(12) min	1/2-

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 47) and isobaric (same nucleon number A = 81) with Selenium-81m. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 47	Isobar A = 81
26	⁷³Fe
27	⁷⁴Co
28	⁷⁵Ni
29	⁷⁶Cu	⁸¹Cu
30	⁷⁷Zn	⁸¹Zn
31	⁷⁸Ga	⁸¹Ga
32	⁷⁹Ge	⁸¹Ge
33	⁸⁰As	⁸¹As
34	⁸¹Se	⁸¹Se
35	⁸²Br	⁸¹Br
36	⁸³Kr	⁸¹Kr
37	⁸⁴Rb	⁸¹Rb
38	⁸⁵Sr	⁸¹Sr
39	⁸⁶Y	⁸¹Y
40	⁸⁷Zr	⁸¹Zr
41	⁸⁸Nb	⁸¹Nb
42	⁸⁹Mo	⁸¹Mo
43	⁹⁰Tc
44	⁹¹Ru
45	⁹²Rh
46	⁹³Pd
47	⁹⁴Ag
48	⁹⁵Cd
49	⁹⁶In