Krypton-81m

Properties and data of the isotope ^81mKr.

Contents

General Data

Radioactive Decay

Use in Medicine

Isotones und Isobares

Literature

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

General data

Name of the isotope:Krypton-81m; Kr-81mSymbol:^81mKr or 81m36KrMass number A:81 (= number of nucleons)Atomic number Z:36 (= number of protons)Neutrons N:45Isotopic mass:80.9165897(12) u (atomic weight of Krypton-81m)
Excitation energy: 190.64(4) keVNuclide mass:80.8968416 u (calculated nuclear mass without electrons)Mass excess:-77.69619 MeVMass defect:0.755032672 u (per nucleus)Nuclear binding energy:703.30840377 MeV (per nucleus)
8.6828198 MeV (average binding energy per nucleon)Half-life:13.10(3) sDecay constant λ:0.052911998516026 s^-1Specific activity α:3.983043853053 × 10⁺²⁰ Bq g^-1
10764983386.631 Ci g^-1Spin and parity:
(nuclear angular momentum)1/2-Magnetic dipole moment:μ(μ_N) = + 0.586(2)Nuclear g-factor:g_l = 1.172

Radioactive Decay

Half-life T_½ = 13.10(3) s respectively 1.310 × 10¹ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
Iso	⁸¹Kr	99.9975(4) %	0.1906(6) MeV	0.19046(16) MeV 67.6983(3) %
EC	⁸¹Br	0.0025(4) %

Krypton-81m as a Radionuclide in Medicine

Krypton-81m is a radioactive, chemically inert noble gas and approved in nuclear medicine as a radiodiagnostic for the respiratory tract (ATC code V09EX01). In detail, it is used to test lung function through the breathing air of ventilated regions and is only suitable for inhalation in diagnostic studies.

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
⁸¹Kr		2.29(11) × 10⁵ a	7/2+

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 45) and isobaric (same nucleon number A = 81) with Krypton-81m. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 45	Isobar A = 81
23	⁶⁸V
25	⁷⁰Mn
26	⁷¹Fe
27	⁷²Co
28	⁷³Ni
29	⁷⁴Cu	⁸¹Cu
30	⁷⁵Zn	⁸¹Zn
31	⁷⁶Ga	⁸¹Ga
32	⁷⁷Ge	⁸¹Ge
33	⁷⁸As	⁸¹As
34	⁷⁹Se	⁸¹Se
35	⁸⁰Br	⁸¹Br
36	⁸¹Kr	⁸¹Kr
37	⁸²Rb	⁸¹Rb
38	⁸³Sr	⁸¹Sr
39	⁸⁴Y	⁸¹Y
40	⁸⁵Zr	⁸¹Zr
41	⁸⁶Nb	⁸¹Nb
42	⁸⁷Mo	⁸¹Mo
43	⁸⁸Tc
44	⁸⁹Ru
45	⁹⁰Rh
46	⁹¹Pd
47	⁹²Ag

External data and identifiers

CAS:15678-91-8PubChem:ID 66380Adopted Levels, Gammas:NuDat 81Kr

Literature and References

[1] - R. Pommet, F. Therain:
The Use of Kr-81M in Ventilation Imaging.
In: Clinical Nuclear Medicine, 7(3), 122-130, (1982), DOI 10.1097/00003072-198203000-00008.