Strontium-87m

Properties and data of the isotope ^87mSr.

Contents

Strontium-87m is a metastable (m) nuclear isomer nuclide of the stable isotope strontium-87, which has an energy 388.5 keV higher than the ground state. ^87mSr can be produced in different ways - including from ⁸⁷Sr by excitation with neutrons in a nuclear reactor:

⁸⁷Sr(n,n′)^87mSr.

The common method for producing strontium-87m, however, is production using a ⁸⁷Y/^87mSr generator in a cyclotron, which initially produces yttrium-87, which decays to Sr-87m under the reaction conditions:

⁸⁷Sr(p,n)⁸⁷Y → ^87mSr → ⁸⁷Sr, or

^natRb(α,xn)⁸⁷Y → ^87mSr → ⁸⁷Sr

^87mSr can be produced directly from rubidium-87 or from strontium-86:

⁸⁷Rb(p,n)^87mSr
:⁸⁶Sr(n,γ)^87mSr.

General data

Name of the isotope:Strontium-87m; Sr-87mSymbol:^87mSr or 87m38SrMass number A:87 (= number of nucleons)Atomic number Z:38 (= number of protons)Neutrons N:49Isotopic mass:86.908878(8) u (atomic weight of Strontium-87m)
Excitation energy: 388.5287(23) keVNuclide mass:86.8880328 u (calculated nuclear mass without electrons)Mass excess:-84.8796 MeVMass defect:0.8130541 u (per nucleus)Nuclear binding energy:757.35501583 MeV (per nucleus)
8.70523007 MeV (average binding energy per nucleon)Half-life:2.815(12) hDecay constant λ:6.839818241167 × 10^-5 s^-1Specific activity α:4.789575454032 × 10⁺¹⁷ Bq g^-1
12944798.524411 Ci g^-1Spin and parity:
(nuclear angular momentum)1/2-Magnetic dipole moment:μ(μ_N) = +0.624(4)Nuclear g-factor:g_l = 1.248

Radioactive Decay

Strontium-87 decays radioactively in two different ways: 99.70% undergoes an isomer transition with the emission of gamma radiation to the ground state of ⁸⁷Sr. The remaining 0.3% is converted into ⁸⁷Rb after electron capture.

Half-life T_½ = 2.815(12) h (hours) respectively 1.0134 × 10⁴ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
Iso	⁸⁷Sr	99.70(8) %	0.388533(3) MeV	0.388531(3) MeVbr/>[82.19(22) %]
EC	⁸⁷Rb	0.30(8) %	0.106333(3) MeV

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
⁸⁷Sr		stable	9/2+

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 49) and isobaric (same nucleon number A = 87) with Strontium-87m. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 49	Isobar A = 87
27	⁷⁶Co
28	⁷⁷Ni
29	⁷⁸Cu
30	⁷⁹Zn
31	⁸⁰Ga	⁸⁷Ga
32	⁸¹Ge	⁸⁷Ge
33	⁸²As	⁸⁷As
34	⁸³Se	⁸⁷Se
35	⁸⁴Br	⁸⁷Br
36	⁸⁵Kr	⁸⁷Kr
37	⁸⁶Rb	⁸⁷Rb
38	⁸⁷Sr	⁸⁷Sr
39	⁸⁸Y	⁸⁷Y
40	⁸⁹Zr	⁸⁷Zr
41	⁹⁰Nb	⁸⁷Nb
42	⁹¹Mo	⁸⁷Mo
43	⁹²Tc	⁸⁷Tc
44	⁹³Ru	⁸⁷Ru
45	⁹⁴Rh
46	⁹⁵Pd
47	⁹⁶Ag
48	⁹⁷Cd
49	⁹⁸In
50	⁹⁹Sn