Selenium-77

Properties and data of the isotope ⁷⁷Se.

Contents

General Data

Parent Nuclides

NMR Data

Isotones und Isobares

Literature

Selenium-77 is a stable isotope of the chemical element selenium, which has 43 neutrons in its atomic nucleus in addition to the element-specific 34 protons; the sum of the number of these atomic nucleus building blocks results in a mass number of 77. Se-77 accounts for 7.6% of natural terrestrial selenium deposits.

The discovery was reported in 1922 [1]: According to this report, selenium-77 was first detected by mass spectrometric analysis of Se vapors produced in a discharge tube.

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

General data

Name of the isotope:Selenium-77; Se-77Symbol:⁷⁷Se or 7734SeMass number A:77 (= number of nucleons)Atomic number Z:34 (= number of protons)Neutrons N:43Nucleon pairing (Z - N):even - oddNuclear ratio (N/Z ratio):1.2647058823529 (= neutron-proton ratio)Neutron excess (N-Z):9Isotopic mass:76.91991415(7) u (atomic weight of Selenium-77)Nuclide mass:76.9012631 u (calculated nuclear mass without electrons)Mass excess:-74.59949 MeVMass defect:0.718728326 u (per nucleus)Nuclear binding energy:669.4911233 MeV (per nucleus)
8.69468991 MeV (average binding energy per nucleon)Separation energy:S_N = 7.41886(6) MeV (first neutron)
S_P = 9.5971(9) MeV (first proton)Half-life:stableSpin and parity:
(nuclear angular momentum)1/2-Magnetic dipole moment:μ(μ_N) = +0.53356(5)Charge radius:4.1395(18) femtometer fmYear of discovery:1922

Parent Nuclides

Direct parent isotopes are: ⁷⁷Br, ⁷⁷As.

Occurrence

Comparison of the natural Selenium isotopes including isotopic abundance (mole fraction of the isotope mixture in percent):

	Atomic Mass m_a	Quantity	Half-life	Spin
Selenium Isotopic mixture	78.971 u	100 %
Isotope ⁷⁴Se	73.9224759(1) u	0.86(3) %	stable	0+
Isotope ⁷⁶Se	75.9192137(2) u	9.23(7) %	stable	0+
Isotope ⁷⁸Se	77.917309(2) u	23.69(22) %	stable	0+
Isotope ⁸⁰Se	79.916522(8) u	49.80(36) %	stable	0+
Isotope ⁸²Se	81.916700(9) u	8.82(15) %	9.39(17) × 10¹⁹ a	0+
Isotope ⁷⁷Se	76.91991415(7) u	7.60(7) %	stable	1/2-

NMR data

Nuclear magnetic properties and parameters of the NMR active Nuclide ⁷⁷Se

Isotope:⁷⁷Se-NMRQuantity:7.60(7) %Spin:1/2-Nuclearmagnetic moment
μ/μ_N:+0.53356(5)Gyromagnetic ratio γ:5.1253857 · 10⁷ rad T^-1 s^-1
8.15730 MHz T^-1Nuclear g-factor:g_l = 1.06712Resonance frequency:v₀ = 8.1568 MHz at 1 TRelative Sensitivity:[related to ¹H = 1.000]:
0.00703 (H₀ = const.)
0.1916 (v₀ = const.)
0.000537 (at natural abundance)
relative receptivity as compared to ¹³C:
3.15 (at natural abundance)
41.3 (enriched)Reference compound:
(conditions)Pure dimethyl selenide Se(CH₃)₂ containing less than 10% benzene-d6 C₆D₆.Frequency ratio:Ξ(⁷⁷Se) = 19.071513 % [based on the reference substance]Chemical shift range:ca. 3000 ppm [-1000 to 2000]

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
^77mSe	161.9223(10) keV	17.36(5) s	7/2+

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 43) and isobaric (same nucleon number A = 77) with Selenium-77. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 43	Isobar A = 77
22	⁶⁵Ti
23	⁶⁶V
24	⁶⁷Cr
25	⁶⁸Mn
26	⁶⁹Fe
27	⁷⁰Co
28	⁷¹Ni	⁷⁷Ni
29	⁷²Cu	⁷⁷Cu
30	⁷³Zn	⁷⁷Zn
31	⁷⁴Ga	⁷⁷Ga
32	⁷⁵Ge	⁷⁷Ge
33	⁷⁶As	⁷⁷As
34	⁷⁷Se	⁷⁷Se
35	⁷⁸Br	⁷⁷Br
36	⁷⁹Kr	⁷⁷Kr
37	⁸⁰Rb	⁷⁷Rb
38	⁸¹Sr	⁷⁷Sr
39	⁸²Y	⁷⁷Y
40	⁸³Zr	⁷⁷Zr
41	⁸⁴Nb
42	⁸⁵Mo
43	⁸⁶Tc
44	⁸⁷Ru