Yttrium-91

Properties and data of the isotope ⁹¹Y.

Contents

General Data

Radioactive Decay

Parent Nuclides

Isotones und Isobares

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

General data

Name of the isotope:Yttrium-91; Y-91Symbol:⁹¹Y or 9139YMass number A:91 (= number of nucleons)Atomic number Z:39 (= number of protons)Neutrons N:52Nucleon pairing (Z - N):odd - evenNuclear ratio (N/Z ratio):1.3333333333333 (= neutron-proton ratio)Neutron excess (N-Z):13Isotopic mass:90.9072981(20) u (atomic weight of Yttrium-91)Nuclide mass:90.8859044 u (calculated nuclear mass without electrons)Mass excess:-86.35126 MeVMass defect:0.84845377999999 u (per nucleus)Nuclear binding energy:790.32960535 MeV (per nucleus)
8.68494072 MeV (average binding energy per nucleon)Separation energy:S_N = 7.9285(24) MeV (first neutron)
S_P = 7.6921(28) MeV (first proton)Half-life:58.51(6) dDecay constant λ:1.371139431214 × 10^-7 s^-1Specific activity α:9.174660881541 × 10⁺¹⁴ Bq g^-1
24796.380760924 Ci g^-1Spin and parity:
(nuclear angular momentum)1/2-Magnetic dipole moment:μ(μ_N) = 0.1639(8)Nuclear g-factor:g_l = 0.3278Year of discovery:1943

Radioactive Decay

Half-life T_½ = 58.51(6) d respectively 5.055264 × 10⁶ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
β^-	⁹¹Zr	100 %	1.5443(18) MeV

Parent Nuclides

Direct parent isotope is: ⁹¹Sr.

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
^91mY	555.58(5) keV	49.71(4) min	9/2+

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 52) and isobaric (same nucleon number A = 91) with Yttrium-91. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 52	Isobar A = 91
28	⁸⁰Ni
29	⁸¹Cu
30	⁸²Zn
31	⁸³Ga
32	⁸⁴Ge
33	⁸⁵As	⁹¹As
34	⁸⁶Se	⁹¹Se
35	⁸⁷Br	⁹¹Br
36	⁸⁸Kr	⁹¹Kr
37	⁸⁹Rb	⁹¹Rb
38	⁹⁰Sr	⁹¹Sr
39	⁹¹Y	⁹¹Y
40	⁹²Zr	⁹¹Zr
41	⁹³Nb	⁹¹Nb
42	⁹⁴Mo	⁹¹Mo
43	⁹⁵Tc	⁹¹Tc
44	⁹⁶Ru	⁹¹Ru
45	⁹⁷Rh	⁹¹Rh
46	⁹⁸Pd	⁹¹Pd
47	⁹⁹Ag
48	¹⁰⁰Cd
49	¹⁰¹In
50	¹⁰²Sn
51	¹⁰³Sb