Isotopes of manganese

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Naturally occurring manganese (Mn) is composed of 1 stable isotope, 55Mn. 25 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 1 minute, but only 45Mn has an unknown half-life. The least stable is 44Mn with a half-life shorter than 105 nanoseconds. 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 explosion. 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.[1] 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 65 u (65Mn). The primary decay mode before the most abundant stable isotope, 55Mn, is electron capture and the primary mode after is beta decay.

Standard atomic mass: 54.938045(5) u

Table[edit]

nuclide
symbol
Z(p) N(n)  
isotopic mass (u)
 
half-life decay
mode(s)[2][n 1]
daughter
isotope(s)[n 2]
nuclear
spin
representative
isotopic
composition
(mole fraction)
range of natural
variation
(mole fraction)
excitation energy
44Mn 25 19 44.00687(54)# <105 ns p 43Cr (2-)#
45Mn 25 20 44.99451(32)# unknown p 44Cr (7/2-)#
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 a 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-#
  1. ^ Abbreviations:
    EC: Electron capture
    IT: Isomeric transition
  2. ^ Bold for stable isotopes

Notes[edit]

  • Values marked # are not purely derived from experimental data, but at least partly from systematic trends. Spins with weak assignment arguments are enclosed in parentheses.
  • Uncertainties are given in concise form in parentheses after the corresponding last digits. Uncertainty values denote one standard deviation, except isotopic composition and standard atomic mass from IUPAC which use expanded uncertainties.
  • Nuclide masses are given by IUPAP Commission on Symbols, Units, Nomenclature, Atomic Masses and Fundamental Constants (SUNAMCO)
  • Isotope abundances are given by IUPAC Commission on Isotopic Abundances and Atomic Weights

References[edit]

  1. ^ 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. 
  2. ^ http://www.nucleonica.net/unc.aspx


Isotopes of chromium Isotopes of manganese Isotopes of iron
Table of nuclides