Strontium-91

Properties and data of the isotope ⁹¹Sr.

Contents

General data

Name of the isotope:Strontium-91; Sr-91Symbol:⁹¹Sr or 9138SrMass number A:91 (= number of nucleons)Atomic number Z:38 (= number of protons)Neutrons N:53Isotopic mass:90.910196(6) u (atomic weight of Strontium-91)Nuclide mass:90.8893508 u (calculated nuclear mass without electrons)Mass excess:-83.65189 MeVMass defect:0.84639576400001 u (per nucleus)Nuclear binding energy:788.41257579 MeV (per nucleus)
8.66387446 MeV (average binding energy per nucleon)Separation energy:S_N = 5.775(6) MeV (first neutron)
S_P = 11.576(8) MeV (first proton)Half-life:9.65(6) hDecay constant λ:1.995242315946 × 10^-5 s^-1Specific activity α:1.335070030704 × 10⁺¹⁷ Bq g^-1
3608297.3802819 Ci g^-1Spin and parity:
(nuclear angular momentum)5/2+Magnetic dipole moment:μ(μ_N) = -0.885(2)Quadrupole moment Q:0.045(11) barn (100 fm²)Nuclear g-factor:g_l = -0.354Charge radius:4.2740(46) femtometer fmYear of discovery:1943

Radioactive Decay

Half-life T_½ = 9.65(6) h (hours) respectively 3.4740 × 10⁴ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
β^-	⁹¹Y	100%	2.699(5) MeV

Parent Nuclides

Direct parent isotope is: ⁹¹Rb.

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 53) and isobaric (same nucleon number A = 91) with Strontium-91. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 53	Isobar A = 91
29	⁸²Cu
30	⁸³Zn
31	⁸⁴Ga
32	⁸⁵Ge
33	⁸⁶As	⁹¹As
34	⁸⁷Se	⁹¹Se
35	⁸⁸Br	⁹¹Br
36	⁸⁹Kr	⁹¹Kr
37	⁹⁰Rb	⁹¹Rb
38	⁹¹Sr	⁹¹Sr
39	⁹²Y	⁹¹Y
40	⁹³Zr	⁹¹Zr
41	⁹⁴Nb	⁹¹Nb
42	⁹⁵Mo	⁹¹Mo
43	⁹⁶Tc	⁹¹Tc
44	⁹⁷Ru	⁹¹Ru
45	⁹⁸Rh	⁹¹Rh
46	⁹⁹Pd	⁹¹Pd
47	¹⁰⁰Ag
48	¹⁰¹Cd
49	¹⁰²In
50	¹⁰³Sn
51	¹⁰⁴Sb
52	¹⁰⁵Te