Xenon-131m

Properties and data of the isotope ¹³¹Xe.

Content

General data

Name of the isotope:Xenon-131m; Xe-131mSymbol:¹³¹Xe or 13154XeMass number A:131 (= number of nucleons)Atomic number Z:54 (= number of protons)Neutrons N:77Isotopic mass:130.905084(2) u (atomic weight of Xenon-131m)
Excitation energy: 163.930(8) keVNuclide mass:130.8754626 u (calculated nuclear mass without electrons)Mass excess:-88.41368 MeVMass defect:1.18466626 u (per nucleus)Nuclear binding energy:1103.50951319 MeV (per nucleus)
8.42373674 MeV (average binding energy per nucleon)Half-life:11.84(4) dDecay constant λ:6.775791226382 × 10^-7 s^-1Specific activity α:3.138828400215 × 10⁺¹⁵ Bq g^-1
84833.200005814 Ci g^-1Spin and parity:
(nuclear angular momentum)11/2-Magnetic dipole moment:μ(μ_N) = -0.993989(12)Quadrupole moment Q:+0.73(3) barn (100 fm²)Nuclear g-factor:g_l = -0.18072527272727

Radioactive Decay

Half-life T_½ = 11.84(4) d respectively 1.022976 × 10⁶ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
Iso	¹³¹Xe	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
¹³¹Xe		stable	3/2+

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 77) and isobaric (same nucleon number A = 131) with Xenon-131m. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 77	Isobar A = 131
43	¹²⁰Tc
44	¹²¹Ru
45	¹²²Rh
46	¹²³Pd
47	¹²⁴Ag	¹³¹Ag
48	¹²⁵Cd	¹³¹Cd
49	¹²⁶In	¹³¹In
50	¹²⁷Sn	¹³¹Sn
51	¹²⁸Sb	¹³¹Sb
52	¹²⁹Te	¹³¹Te
53	¹³⁰I	¹³¹I
54	¹³¹Xe	¹³¹Xe
55	¹³²Cs	¹³¹Cs
56	¹³³Ba	¹³¹Ba
57	¹³⁴La	¹³¹La
58	¹³⁵Ce	¹³¹Ce
59	¹³⁶Pr	¹³¹Pr
60	¹³⁷Nd	¹³¹Nd
61	¹³⁸Pm	¹³¹Pm
62	¹³⁹Sm	¹³¹Sm
63	¹⁴⁰Eu	¹³¹Eu
64	¹⁴¹Gd
65	¹⁴²Tb
66	¹⁴³Dy
67	¹⁴⁴Ho
68	¹⁴⁵Er
69	¹⁴⁶Tm