Isotopes of manganese

Naturally occurring manganese (₂₅Mn) is composed of one 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 a 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.

Main isotopes of manganese (₂₅Mn)

Iso­tope Decay abun­dance half-life (t1/2) mode pro­duct ^52Mn syn 5.6 d ε ^52Cr β^+ ^52Cr γ – ^53Mn trace 3.74×10^6 y ε ^53Cr ^54Mn syn 312 d ε ^54Cr γ – ^55Mn 100% stable
Standard atomic weight Ar, standard(Mn)	54.938044(3)[1]

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.[2] 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 44 u (⁴⁴Mn) to 69 u (⁶⁹Mn). 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
^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)×10^6 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−#

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. # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).

References

1. Meija, Juris; et al. (2016). "Atomic weights of the elements 2013 (IUPAC Technical Report)". Pure and Applied Chemistry. 88 (3): 265–91. doi:10.1515/pac-2015-0305.
2. 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.

• Isotope masses from:
  • Audi, Georges; Bersillon, Olivier; Blachot, Jean; Wapstra, Aaldert Hendrik (2003), "The NUBASE evaluation of nuclear and decay properties", Nuclear Physics A, 729: 3–128, Bibcode:2003NuPhA.729....3A, doi:10.1016/j.nuclphysa.2003.11.001
• Isotopic compositions and standard atomic masses from:
  • de Laeter, John Robert; Böhlke, John Karl; De Bièvre, Paul; Hidaka, Hiroshi; Peiser, H. Steffen; Rosman, Kevin J. R.; Taylor, Philip D. P. (2003). "Atomic weights of the elements. Review 2000 (IUPAC Technical Report)". Pure and Applied Chemistry. 75 (6): 683–800. doi:10.1351/pac200375060683.
  • Wieser, Michael E. (2006). "Atomic weights of the elements 2005 (IUPAC Technical Report)". Pure and Applied Chemistry. 78 (11): 2051–2066. doi:10.1351/pac200678112051. Lay summary.
• Half-life, spin, and isomer data selected from the following sources.
  • Audi, Georges; Bersillon, Olivier; Blachot, Jean; Wapstra, Aaldert Hendrik (2003), "The NUBASE evaluation of nuclear and decay properties", Nuclear Physics A, 729: 3–128, Bibcode:2003NuPhA.729....3A, doi:10.1016/j.nuclphysa.2003.11.001
  • National Nuclear Data Center. "NuDat 2.x database". Brookhaven National Laboratory.
  • Holden, Norman E. (2004). "11. Table of the Isotopes". In Lide, David R. (ed.). CRC Handbook of Chemistry and Physics (85th ed.). Boca Raton, Florida: CRC Press. ISBN 978-0-8493-0485-9.