Isotopes of manganese (25Mn)
Main isotopes[1] Decay
abun­dance half-life (t1/2) mode pro­duct
52Mn synth 5.591 d β+ 52Cr
53Mn trace 3.7×106 y ε 53Cr
54Mn synth 312.081 d ε 54Cr
β 54Fe
β+ 54Cr
55Mn 100% stable
Standard atomic weight Ar°(Mn)
  • 54.938043±0.000002
  • 54.938±0.001 (abridged)[2][3]

Naturally occurring manganese (25Mn) is composed of one stable isotope, 55Mn. 26 radioisotopes have been characterized, with the most stable being 53Mn with a half-life of 3.7 million years, 54Mn with a half-life of 312.3 days, and 52Mn with a half-life of 5.591 days. All of the remaining radioactive isotopes have half-lives that are less than 3 hours and the majority of these have half-lives that are less than a minute. This element also has 3 meta states.

Manganese is part of the iron group of elements, which are thought to be synthesized in large stars shortly before supernova explosions. 53Mn decays to 53Cr with a half-life of 3.7 million years. Because of its relatively short half-life, 53Mn occurs only in tiny amounts due to the action of cosmic rays on iron in rocks.[4] Manganese isotopic contents are typically combined with chromium isotopic contents and have found application in isotope geology and radiometric dating. Mn−Cr isotopic ratios reinforce the evidence from 26Al and 107Pd for the early history of the Solar System. Variations in 53Cr/52Cr and Mn/Cr ratios from several meteorites indicate an initial 53Mn/55Mn ratio that suggests Mn−Cr isotopic systematics must result from in-situ decay of 53Mn in differentiated planetary bodies. Hence 53Mn provides additional evidence for nucleosynthetic processes immediately before coalescence of the Solar System.

The isotopes of manganese range in atomic weight from 46 u (46Mn) to 72 u (72Mn). The primary decay mode before the most abundant stable isotope, 55Mn, is electron capture and the primary mode after is beta decay.

List of isotopes

Nuclide
[n 1]
Z N Isotopic mass (Da)
[n 2][n 3]
Half-life
Decay
mode

[n 4]
Daughter
isotope

[n 5]
Spin and
parity
[n 6][n 7]
Natural abundance (mole fraction)
Excitation energy[n 7] Normal proportion Range of variation
46Mn 25 21 45.98672(12)# 37(3) ms β+ (78%) 46Cr (4+)
β+, p (22%) 45V
β+, α (<1%) 42Ti
β+, 2p (<1%) 44Ti
46mMn 150(100)# keV 1# ms β+ 46Cr 1-#
47Mn 25 22 46.97610(17)# 100(50) ms β+ (96.6%) 47Cr 5/2−#
β+, p (3.4%) 46V
48Mn 25 23 47.96852(12) 158.1(22) ms β+ (99.71%) 48Cr 4+
β+, p (.027%) 47V
β+, α (6×10−4%) 44Ti
49Mn 25 24 48.959618(26) 382(7) ms β+ 49Cr 5/2−
50Mn 25 25 49.9542382(11) 283.29(8) ms β+ 50Cr 0+
50mMn 229(7) keV 1.75(3) min β+ 50Cr 5+
51Mn 25 26 50.9482108(11) 46.2(1) min β+ 51Cr 5/2−
52Mn 25 27 51.9455655(21) 5.591(3) d β+ 52Cr 6+
52mMn 377.749(5) keV 21.1(2) min β+ (98.25%) 52Cr 2+
IT (1.75%) 52Mn
53Mn 25 28 52.9412901(9) 3.7(4)×106 y EC 53Cr 7/2− trace
54Mn 25 29 53.9403589(14) 312.03(3) d EC 99.99% 54Cr 3+
β (2.9×10−4%) 54Fe
β+ (5.76×10−7%) 54Cr
55Mn 25 30 54.9380451(7) Stable 5/2− 1.0000
56Mn 25 31 55.9389049(7) 2.5789(1) h β 56Fe 3+
57Mn 25 32 56.9382854(20) 85.4(18) s β 57Fe 5/2−
58Mn 25 33 57.93998(3) 3.0(1) s β 58Fe 1+
58mMn 71.78(5) keV 65.2(5) s β (>99.9%) 58Fe (4)+
IT (<.1%) 58Mn
59Mn 25 34 58.94044(3) 4.59(5) s β 59Fe (5/2)−
60Mn 25 35 59.94291(9) 51(6) s β 60Fe 0+
60mMn 271.90(10) keV 1.77(2) s β (88.5%) 60Fe 3+
IT (11.5%) 60Mn
61Mn 25 36 60.94465(24) 0.67(4) s β 61Fe (5/2)−
62Mn 25 37 61.94843(24) 671(5) ms β (>99.9%) 62Fe (3+)
β, n (<.1%) 61Fe
62mMn 0(150)# keV 92(13) ms (1+)
63Mn 25 38 62.95024(28) 275(4) ms β 63Fe 5/2−#
64Mn 25 39 63.95425(29) 88.8(25) ms β (>99.9%) 64Fe (1+)
β, n (<.1%) 63Fe
64mMn 135(3) keV >100 µs
65Mn 25 40 64.95634(58) 92(1) ms β (>99.9%) 65Fe 5/2−#
β, n (<.1%) 64Fe
66Mn 25 41 65.96108(43)# 64.4(18) ms β (>99.9%) 66Fe
β, n (<.1%) 65Fe
67Mn 25 42 66.96414(54)# 45(3) ms β 67Fe 5/2−#
68Mn 25 43 67.96930(64)# 28(4) ms
69Mn 25 44 68.97284(86)# 14(4) ms 5/2−#
70Mn[5] 25 45 69.978050(540)# 19.9(17) ms β=? 70Fe (4,5)
β, n?[n 8] 69Fe
β, 2n?[n 8] 68Fe
71Mn[6] 25 46 70.982160(540)# 16# ms
(>400 ns)
β?[n 8] 71Fe 5/2-#
β, n?[n 8] 70Fe
β, 2n?[n 8] 69Fe
72Mn[7] 25 47 71.988010(640)# 12# ms
(>620 ns)
β?[n 8] 72Fe
β, n?[n 8] 71Fe
β, 2n?[n 8] 70Fe
73Mn[8] 25 48 72.992810(640)# 12# ms
(>410 ns)
β?[n 8] 73Fe 5/2−#
This table header & footer:
  1. mMn  Excited nuclear isomer.
  2. ()  Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
  3. #  Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
  4. Modes of decay:
    EC:Electron capture
    IT:Isomeric transition
    n:Neutron emission
    p:Proton emission
  5. Bold symbol as daughter  Daughter product is stable.
  6. () spin value  Indicates spin with weak assignment arguments.
  7. 1 2 #  Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
  8. 1 2 3 4 5 6 7 8 9 Decay mode shown is energetically allowed, but has not been experimentally observed to occur in this nuclide.

References

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  2. "Standard Atomic Weights: Manganese". CIAAW. 2017.
  3. Prohaska, Thomas; Irrgeher, Johanna; Benefield, Jacqueline; et al. (2022-05-04). "Standard atomic weights of the elements 2021 (IUPAC Technical Report)". Pure and Applied Chemistry. doi:10.1515/pac-2019-0603. ISSN 1365-3075.
  4. J. Schaefer; et al. (2006). "Terrestrial manganese-53 — A new monitor of Earth surface processes". Earth and Planetary Science Letters. 251 (3–4): 334–345. Bibcode:2006E&PSL.251..334S. doi:10.1016/j.epsl.2006.09.016.
  5. Tarasov, O. B.; et al. (April 2009). "Evidence for a Change in the Nuclear Mass Surface with the Discovery of the Most Neutron-Rich Nuclei with 17 ≤ Z ≤ 25". Physical Review Letters. 102 (14): 142501. arXiv:0903.1975. Bibcode:2009PhRvL.102n2501T. doi:10.1103/PhysRevLett.102.142501. PMID 19392430. S2CID 42329617. Retrieved 29 January 2023.
  6. Ohnishi, Tetsuya; et al. (July 2010). "Identification of 45 New Neutron-Rich Isotopes Produced by In-Flight Fission of a 238U Beam at 345 MeV/nucleon". Journal of the Physical Society of Japan. 79 (7): 073201. arXiv:1006.0305. Bibcode:2010JPSJ...79g3201T. doi:10.1143/JPSJ.79.073201. S2CID 117037614. Retrieved 29 January 2023.
  7. Tarasov, O. B.; et al. (May 2013). "Production cross sections from 82 Se fragmentation as indications of shell effects in neutron-rich isotopes close to the drip-line". Physical Review C. 87 (5): 054612. arXiv:1303.7164. Bibcode:2013PhRvC..87e4612T. doi:10.1103/PhysRevC.87.054612. S2CID 41501572. Retrieved 29 January 2023.
  8. T. Sumikama; et al. (May 2017). "Observation of new neutron-rich Mn, Fe, Co, Ni, and Cu isotopes in the vicinity of 78 Ni". Physical Review C. 95 (5): 051601. Bibcode:2017PhRvC..95e1601S. doi:10.1103/PhysRevC.95.051601. hdl:10261/161832. Retrieved 29 January 2023.
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