Iron-61

Properties and data of the isotope ⁶¹Fe.

Contents

General data

Name of the isotope:Iron-61; Fe-61Symbol:⁶¹Fe or 6126FeMass number A:61 (= number of nucleons)Atomic number Z:26 (= number of protons)Neutrons N:35Isotopic mass:60.9367462(28) u (atomic weight of Iron-61)Nuclide mass:60.9224835 u (calculated nuclear mass without electrons)Mass excess:-58.92054 MeVMass defect:0.569976692 u (per nucleus)Nuclear binding energy:530.92986874 MeV (per nucleus)
8.70376834 MeV (average binding energy per nucleon)Separation energy:S_N = 5.579(4) MeV (first neutron)
S_P = 13.242(4) MeV (first proton)Half-life:5.98(6) minDecay constant λ:0.0019318483293198 s^-1Specific activity α:1.938977126532 × 10⁺¹⁹ Bq g^-1
524047872.03592 Ci g^-1Spin and parity:
(nuclear angular momentum)(3/2-)Year of discovery:1957

Radioactive Decay

Half-life T_½ = 5.98(6) min (minutes) respectively 3.588 × 10² seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
β^-	⁶¹Co	100 %	3.9776(27) MeV

Parent Nuclides

Direct parent isotope is: ⁶¹Mn.

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
^61mFe	861.67(11) keV	0.238(5) μs	(9/2+)

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 35) and isobaric (same nucleon number A = 61) with Iron-61. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 35	Isobar A = 61
18	⁵³Ar
19	⁵⁴K
20	⁵⁵Ca
21	⁵⁶Sc	⁶¹Sc
22	⁵⁷Ti	⁶¹Ti
23	⁵⁸V	⁶¹V
24	⁵⁹Cr	⁶¹Cr
25	⁶⁰Mn	⁶¹Mn
26	⁶¹Fe	⁶¹Fe
27	⁶²Co	⁶¹Co
28	⁶³Ni	⁶¹Ni
29	⁶⁴Cu	⁶¹Cu
30	⁶⁵Zn	⁶¹Zn
31	⁶⁶Ga	⁶¹Ga
32	⁶⁷Ge	⁶¹Ge
33	⁶⁸As
34	⁶⁹Se
35	⁷⁰Br
36	⁷¹Kr
37	⁷²Rb
38	⁷³Sr