Isotopes of promethium

{{Short description|none}} {{Infobox promethium isotopes}} Promethium (₆₁Pm) is an artificial element, except in trace quantities as a product of spontaneous fission of ²³⁸U and ²³⁵U and alpha decay of ¹⁵¹Eu, and thus a standard atomic weight cannot be given. Like all artificial elements, it has no stable isotopes. It was first synthesized in 1945. Like technetium, it is preceded and followed by elements with stable isotopes.

The known isotopes run from ¹²⁸Pm to ¹⁶⁶Pm, 39 in all; the most stable are ¹⁴⁵Pm with a half-life of 17.7 years, ¹⁴⁶Pm with a half-life of 5.53 years, and ¹⁴⁷Pm (the common isotope) with a half-life of 2.6234 years. ¹⁴³Pm and ¹⁴⁴Pm also have lengthy if poorly-known lives on the order of a year, but all the others have half-lives that are less than six days, with the majority less than a few minutes. There are also 24 known meta states with the most stable being ^148mPm at a half-life of 41.29 days.

The primary decay mode for isotopes lighter than ¹⁴⁶Pm is electron capture resulting in isotopes of neodymium, and the primary decay mode heavier than ¹⁴⁶Pm is beta decay giving isotopes of samarium; promethium-146 itself decays both ways.

== List of isotopes == {{Anchor|Promethium-138m|Promethium-152m1|Promethium-152m2}}

<!--Please delete anchor(s) from the list above or table below if adding a dedicated isotope section(s).-->

{{Isotopes table | symbol = Pm | refs = NUBASE2020, AME2020 II, <!-- updated 2024-12-18 --> IsotopeFRIB, IsomerFRIB | notes = m, unc(), hl#, mass#, exen#, spin(), spin#, daughter-st, daughter-nst, IT, EC, p, n, discoveryname }} |-id=Promethium-125 | ¹²⁵Pm<ref name="suzuki2025">{{cite journal |last1=Suzuki |first1=H |last2=Fukuda |first2=N |last3=Takeda |first3=H |last4=Shimizu |first4=Y |last5=Yoshimoto |first5=M |last6=Togano |first6=Y |last7=Sato |first7=H |last8=Kitamura |first8=N |last9=Hanai |first9=S |last10=Momota |first10=S |last11=Kusaka |first11=K |last12=Yanagisawa |first12=Y |last13=Ohtake |first13=M |last14=Sumikama |first14=T |last15=Fukunishi |first15=N |last16=Michimasa |first16=S |title=Discovery of Proton-Rich Radioactive Isotopes in the Z = 60 Region Produced by the Projectile Fragmentation of a 345-MeV/Nucleon 238U Beam |journal=Progress of Theoretical and Experimental Physics |date=7 November 2025 |volume=2025 |issue=11 |doi=10.1093/ptep/ptaf149|doi-access=free }}</ref> | style="text-align:right" | 61 | style="text-align:right" | 64 | | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/61/125.pdf 2025] | >310&nbsp;ns | | | | |-id=Promethium-126 | ¹²⁶Pm<ref name="suzuki2025"/> | style="text-align:right" | 61 | style="text-align:right" | 65 | 125.95733(54)# | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/61/126.pdf 2025] | 500#&nbsp;ms<br>[>310&nbsp;ns] | | | | |-id=Promethium-127 | ¹²⁷Pm<ref name="suzuki2025"/> | style="text-align:right" | 61 | style="text-align:right" | 66 | 126.95136(43)# | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/61/127.pdf 2025] | 1#&nbsp;s<br>[>310&nbsp;ns] | | | 3/2+# | |-id=Promethium-128 | rowspan=2|¹²⁸Pm | rowspan=2 style="text-align:right" | 61 | rowspan=2 style="text-align:right" | 67 | rowspan=2|127.94823(32)# | rowspan=2 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/61/128.pdf 1999] | rowspan=2|1.0(3)&nbsp;s | β⁺ (?%) | ¹²⁸Nd | rowspan=2|4+# | rowspan=2| |- | β⁺, p (?%) | ¹²⁷Pr |-id=Promethium-129 | ¹²⁹Pm | style="text-align:right" | 61 | style="text-align:right" | 68 | 128.94291(32)# | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/61/129.pdf 2004] | 2.4(9)&nbsp;s | β⁺ | ¹²⁹Nd | 5/2+# | |-id=Promethium-130 | rowspan=2|¹³⁰Pm | rowspan=2 style="text-align:right" | 61 | rowspan=2 style="text-align:right" | 69 | rowspan=2|129.94045(22)# | rowspan=2 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/61/130.pdf 1985] | rowspan=2|2.6(2)&nbsp;s | β⁺ (?%) | ¹³⁰Nd | rowspan=2|(5+, 6+, 4+) | rowspan=2| |- | β⁺, p (?%) | ¹²⁹Pr |-id=Promethium-131 | ¹³¹Pm | style="text-align:right" | 61 | style="text-align:right" | 70 | 130.93583(22)# | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/61/131.pdf 1998] | 6.3(8)&nbsp;s | β⁺ | ¹³¹Nd | (11/2−) | |-id=Promethium-132 | rowspan=2|¹³²Pm | rowspan=2 style="text-align:right" | 61 | rowspan=2 style="text-align:right" | 71 | rowspan=2|131.93384(16)# | rowspan=2 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/61/132.pdf 1977] | rowspan=2|6.2(6)&nbsp;s | β⁺ | ¹³²Nd | rowspan=2|(3+) | rowspan=2| |- | β⁺, p (5×10⁻⁵%) | ¹³¹Pr |-id=Promethium-133 | ¹³³Pm | style="text-align:right" | 61 | style="text-align:right" | 72 | 132.929782(54) | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/61/133.pdf 1977] | 13.5(21)&nbsp;s | β⁺ | ¹³³Nd | (3/2+) | |-id=Promethium-133m | style="text-indent:1em" | ^133mPm | colspan="3" style="text-indent:2em" | 129.7(7)&nbsp;keV | style="text-align:center" | (1996)<ref group="n">Half-life not measured, not included in discovery database</ref> | 8#&nbsp;s | | | (11/2−) | |-id=Promethium-134 | ¹³⁴Pm | style="text-align:right" | 61 | style="text-align:right" | 73 | 133.928326(45) | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/61/134.pdf 1977] | 22(1)&nbsp;s | β⁺ | ¹³⁴Nd | (5+) | |-id=Promethium-134m1 | style="text-indent:1em" | ^134m1Pm | colspan="3" style="text-indent:2em" | 50(50)#&nbsp;keV<ref group="n" name="order">Order of ground state and isomer is uncertain.</ref> | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/isomers/abstracts/61/134Pm-1.pdf 1989] | ~5&nbsp;s | β⁺ | ¹³⁴Nd | (2+) | |-id=Promethium-134m2 | style="text-indent:1em" | ^134m2Pm | colspan="3" style="text-indent:2em" | 120(50)#&nbsp;keV | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/isomers/abstracts/61/134Pm-2.pdf 2009] | 20(1)&nbsp;μs | IT | ¹³⁴Pm | (7−) | |-id=Promethium-135 | ¹³⁵Pm | style="text-align:right" | 61 | style="text-align:right" | 74 | 134.924785(89) | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/61/135.pdf 1975] | 49(3)&nbsp;s | β⁺ | ¹³⁵Nd | (3/2+, 5/2+) | |-id=Promethium-135m | style="text-indent:1em" | ^135mPm | colspan="3" style="text-indent:2em" | 240(100)#&nbsp;keV | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/isomers/abstracts/61/135Pm-1.pdf 1989] | 40(3)&nbsp;s | β⁺ | ¹³⁵Nd | (11/2−) | |-id=Promethium-136 | ¹³⁶Pm | style="text-align:right" | 61 | style="text-align:right" | 75 | 135.923596(74) | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/61/136.pdf 1982] | 107(6)&nbsp;s | β⁺ | ¹³⁶Nd | 7+# | |-id=Promethium-136m1 | style="text-indent:1em" | ^136m1Pm<ref group="n" name="order"/> | colspan="3" style="text-indent:2em" | 100(120)&nbsp;keV | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/isomers/abstracts/61/136Pm-1.pdf 1988] | 90(35)&nbsp;s | β⁺ | ¹³⁶Nd | 2+# | |-id=Promethium-136m2 | style="text-indent:1em" | ^136m2Pm | colspan="3" style="text-indent:2em" | 42.7(2)&nbsp;keV | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/isomers/abstracts/61/136Pm-2.pdf 2008] | 1.5(1)&nbsp;μs | IT | ¹³⁶Pm | 7−# | |-id=Promethium-137 | ¹³⁷Pm | style="text-align:right" | 61 | style="text-align:right" | 76 | 136.920480(14) | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/61/137.pdf 1975] | 2#&nbsp;min | | | 5/2−# | |-id=Promethium-137m | style="text-indent:1em" | ^137mPm | colspan="3" style="text-indent:2em" | 160(50)&nbsp;keV | style="text-align:center" | (1973)<ref group="n">Not clear that this is a different state from the ground state</ref> | 2.4(1)&nbsp;min | β⁺ | ¹³⁷Nd | 11/2− | |-id=Promethium-138 | ¹³⁸Pm | style="text-align:right" | 61 | style="text-align:right" | 77 | 137.919576(12) | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/61/138.pdf 1981] | 3.24(5)&nbsp;min | β⁺ | ¹³⁸Nd | 3−# | |-id=Promethium-139 | ¹³⁹Pm | style="text-align:right" | 61 | style="text-align:right" | 78 | 138.916799(15) | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/61/139.pdf 1967] | 4.15(5)&nbsp;min | β⁺ | ¹³⁹Nd | (5/2)+ | |-id=Promethium-139m | style="text-indent:1em" | ^139mPm | colspan="3" style="text-indent:2em" | 188.7(3)&nbsp;keV | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/isomers/abstracts/61/139Pm-1.pdf 1975] | 180(20)&nbsp;ms | IT | ¹³⁹Pm | (11/2)− | |-id=Promethium-140 | ¹⁴⁰Pm | style="text-align:right" | 61 | style="text-align:right" | 79 | 139.916036(26) | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/61/140.pdf 1966] | 9.2(2)&nbsp;s | β⁺ | ¹⁴⁰Nd | 1+ | |-id=Promethium-140m | style="text-indent:1em" | ^140mPm | colspan="3" style="text-indent:2em" | 429(28)&nbsp;keV | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/isomers/abstracts/61/140Pm-1.pdf 1968] | 5.95(5)&nbsp;min | β⁺ | ¹⁴⁰Nd | 8− | |-id=Promethium-141 | ¹⁴¹Pm | style="text-align:right" | 61 | style="text-align:right" | 80 | 140.913555(15) | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/61/141.pdf 1952] | 20.90(5)&nbsp;min | β⁺ | ¹⁴¹Nd | 5/2+ | |-id=Promethium-141m1 | style="text-indent:1em" | ^141m1Pm | colspan="3" style="text-indent:2em" | 628.62(7)&nbsp;keV | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/isomers/abstracts/61/141Pm-1.pdf 1975] | 630(20)&nbsp;ns | IT | ¹⁴¹Pm | 11/2− | |-id=Promethium-141m2 | style="text-indent:1em" | ^141m2Pm | colspan="3" style="text-indent:2em" | 2530.75(17)&nbsp;keV | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/isomers/abstracts/61/141Pm-2.pdf 1985] | >2&nbsp;μs | IT | ¹⁴¹Pm | (23/2+) | |-id=Promethium-142 | rowspan=2|¹⁴²Pm | rowspan=2 style="text-align:right" | 61 | rowspan=2 style="text-align:right" | 81 | rowspan=2|141.912891(25) | rowspan=2 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/61/142.pdf 1959] | rowspan=2|40.5(5)&nbsp;s | β⁺ (77.1%) | rowspan=2|'''¹⁴²Nd''' | rowspan=2|1+ | rowspan=2| |- | EC (22.9%) |-id=Promethium-142m1 | style="text-indent:1em" | ^142m1Pm | colspan="3" style="text-indent:2em" | 883.17(16)&nbsp;keV | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/isomers/abstracts/61/142Pm-1.pdf 1971] | 2.0(2)&nbsp;ms | IT | ¹⁴²Pm | (8)− | |-id=Promethium-142m2 | style="text-indent:1em" | ^142m2Pm | colspan="3" style="text-indent:2em" | 2828.7(6)&nbsp;keV | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/isomers/abstracts/61/142Pm-2.pdf 2004] | 67(5)&nbsp;μs | IT | ¹⁴²Pm | (13−) | |-id=Promethium-143 | rowspan=2|¹⁴³Pm | rowspan=2 style="text-align:right" | 61 | rowspan=2 style="text-align:right" | 82 | rowspan=2 | 142.9109381(32) | rowspan=2 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/61/143.pdf 1952] | rowspan=2 | 265(7)&nbsp;d | EC | rowspan=2 | '''¹⁴³Nd''' | rowspan=2 | 5/2+ | rowspan=2 | |- | β⁺ (<5.7×10⁻⁶%) |-id=Promethium-144 | rowspan=2|¹⁴⁴Pm | rowspan=2 style="text-align:right" | 61 | rowspan=2 style="text-align:right" | 83 | rowspan=2 | 143.9125962(31) | rowspan=2 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/61/144.pdf 1952] | rowspan=2 | 363(14)&nbsp;d | EC | rowspan=2 | '''''¹⁴⁴Nd''''' | rowspan=2 | 5− | rowspan=2 | |- | β⁺ (<8×10⁻⁵%) |-id=Promethium-144m1 | style="text-indent:1em" | ^144m1Pm | colspan="3" style="text-indent:2em" | 840.90(5)&nbsp;keV | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/isomers/abstracts/61/144Pm-1.pdf 1976] | 780(200)&nbsp;ns | IT | ¹⁴⁴Pm | (9)+ | |-id=Promethium-144m2 | style="text-indent:1em" | ^144m2Pm | colspan="3" style="text-indent:2em" | 8595.8(22)&nbsp;keV | style="text-align:center" | (1994)<ref group="n" | name="conf">Half-life not measured, not included in discovery database</ref> | ~2.7&nbsp;μs | IT | ¹⁴⁴Pm | (27+) | |-id=Promethium-145 | rowspan=2|¹⁴⁵Pm | rowspan=2 style="text-align:right" | 61 | rowspan=2 style="text-align:right" | 84 | rowspan=2|144.9127557(30) | rowspan=2 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/61/145.pdf 1951] | rowspan=2|17.7(4)&nbsp;y | EC | '''¹⁴⁵Nd''' | rowspan=2|5/2+ | rowspan=2| |- | α (2.8×10⁻⁷%) | '''¹⁴¹Pr''' |-id=Promethium-146 | rowspan=2|¹⁴⁶Pm | rowspan=2 style="text-align:right" | 61 | rowspan=2 style="text-align:right" | 85 | rowspan=2|145.9147022(46) | rowspan=2 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/61/146.pdf 1960] | rowspan=2|5.53(5)&nbsp;y | EC (66.0%) | '''¹⁴⁶Nd''' | rowspan=2|3− | rowspan=2| |- | β⁻ (34.0%) | ¹⁴⁶Sm |-id=Promethium-147 | ¹⁴⁷Pm<ref group="n" name="FP">Fission product</ref> | style="text-align:right" | 61 | style="text-align:right" | 86 | 146.9151449(14) | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/61/147.pdf 1947] | 2.6234(2)&nbsp;y | β⁻ | '''''¹⁴⁷Sm''''' | 7/2+ | Trace<ref group="n">Spontaneous fission product of ²³²Th, ²³⁵U, ²³⁸U and alpha decay daughter of primordial ¹⁵¹Eu</ref> |-id=Promethium-148 | ¹⁴⁸Pm | style="text-align:right" | 61 | style="text-align:right" | 87 | 147.9174811(61) | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/61/148.pdf 1947] | 5.368(7)&nbsp;d | β⁻ | '''''¹⁴⁸Sm''''' | 1− | |-id=Promethium-148m | rowspan=2 style="text-indent:1em" | ^148mPm | rowspan=2 colspan="3" style="text-indent:2em" | 137.9(3)&nbsp;keV | rowspan=2 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/isomers/abstracts/61/148Pm-1.pdf 1952] | rowspan=2|41.29(11)&nbsp;d | β⁻ (95.8%) | '''''¹⁴⁸Sm''''' | rowspan=2|5−, 6− | rowspan=2| |- | IT (4.2%) | ¹⁴⁸Pm |-id=Promethium-149 | ¹⁴⁹Pm<ref group="n" name="FP" /> | style="text-align:right" | 61 | style="text-align:right" | 88 | 148.9183415(23) | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/61/149.pdf 1947] | 53.08(5)&nbsp;h | β⁻ | '''¹⁴⁹Sm''' | 7/2+ | |-id=Promethium-149m | style="text-indent:1em" | ^149mPm | colspan="3" style="text-indent:2em" | 240.214(7)&nbsp;keV | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/isomers/abstracts/61/149Pm-1.pdf 1966] | 35(3)&nbsp;μs | IT | ¹⁴⁹Pm | 11/2− | |-id=Promethium-150 | ¹⁵⁰Pm | style="text-align:right" | 61 | style="text-align:right" | 89 | 149.920990(22) | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/61/150.pdf 1952] | 2.698(15)&nbsp;h | β⁻ | '''¹⁵⁰Sm''' | (1−) | |-id=Promethium-151 | ¹⁵¹Pm<ref group="n" name="FP" /> | style="text-align:right" | 61 | style="text-align:right" | 90 | 150.9212166(49) | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/61/151.pdf 1952] | 28.40(4)&nbsp;h | β⁻ | ¹⁵¹Sm | 5/2+ | |-id=Promethium-152 | ¹⁵²Pm | style="text-align:right" | 61 | style="text-align:right" | 91 | 151.923505(28) | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/61/152.pdf 1958] | 4.12(8)&nbsp;min | β⁻ | '''¹⁵²Sm''' | 1+ | |-id=Promethium-152m1 | style="text-indent:1em" | ^152m1Pm | colspan="3" style="text-indent:2em" | 140(90)&nbsp;keV<ref group="n" name="order"/> | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/isomers/abstracts/61/152Pm-1.pdf 1969] | 7.52(8)&nbsp;min | β⁻ | '''¹⁵²Sm''' | 4(−) | |-id=Promethium-152m2 | rowspan=2 style="text-indent:1em" | ^152m2Pm | rowspan=2 colspan="3" style="text-indent:2em" | 150+x&nbsp;keV | rowspan=2 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/isomers/abstracts/61/152Pm-2.pdf 1971] | rowspan=2|13.8(2)&nbsp;min | β⁻ (≤100%) | '''¹⁵²Sm''' | rowspan=2|(8) | rowspan=2| |- | IT (≥0%) | ¹⁵²Pm |-id=Promethium-153 | ¹⁵³Pm | style="text-align:right" | 61 | style="text-align:right" | 92 | 152.9241563(97) | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/61/153.pdf 1962] | 5.25(2)&nbsp;min | β⁻ | ¹⁵³Sm | 5/2− | |-id=Promethium-154 | ¹⁵⁴Pm | style="text-align:right" | 61 | style="text-align:right" | 93 | 153.926713(27) | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/61/154.pdf 1958] | 2.68(7)&nbsp;min | β⁻ | '''¹⁵⁴Sm''' | (4+) | |-id=Promethium-154m | style="text-indent:1em" | ^154mPm<ref group="n" name="order"/> | colspan="3" style="text-indent:2em" | −230(50)&nbsp;keV | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/isomers/abstracts/61/154Pm-1.pdf 1971] | 1.73(10)&nbsp;min | β⁻ | '''¹⁵⁴Sm''' | (1−) | |-id=Promethium-155 | ¹⁵⁵Pm | style="text-align:right" | 61 | style="text-align:right" | 94 | 154.9281370(51) | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/61/155.pdf 1982] | 41.5(2)&nbsp;s | β⁻ | ¹⁵⁵Sm | (5/2−) | |-id=Promethium-156 | ¹⁵⁶Pm | style="text-align:right" | 61 | style="text-align:right" | 95 | 155.9311141(13) | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/61/156.pdf 1986] | 27.4(5)&nbsp;s | β⁻ | ¹⁵⁶Sm | 4+ | |-id=Promethium-156m | rowspan=2 style="text-indent:1em" | ^156mPm | rowspan=2 colspan="3" style="text-indent:2em" | 150.30(10)&nbsp;keV | rowspan=2 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/isomers/abstracts/61/156Pm-1.pdf 2007] | rowspan=2|2.3(20)&nbsp;s | IT (98%) | ¹⁵⁶Pm | rowspan=2|1+# | rowspan=2| |- | β⁻ (2%) | ¹⁵⁶Sm |-id=Promethium-157 | ¹⁵⁷Pm | style="text-align:right" | 61 | style="text-align:right" | 96 | 156.9331213(75) | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/61/157.pdf 1987] | 10.56(10)&nbsp;s | β⁻ | ¹⁵⁷Sm | (5/2−) | |-id=Promethium-158 | ¹⁵⁸Pm | style="text-align:right" | 61 | style="text-align:right" | 97 | 157.93654695(95) | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/61/158.pdf 1987] | 4.8(5)&nbsp;s | β⁻ | ¹⁵⁸Sm | (0+,1+)# | |-id=Promethium-158m | style="text-indent:1em" | ^158mPm | colspan="3" style="text-indent:2em" | 150(50)#&nbsp;keV | style="text-align:center" | (2015)<ref group="n" name=conf /> | >16&nbsp;μs | IT | ¹⁵⁸Pm | 5+# | |-id=Promethium-159 | ¹⁵⁹Pm | style="text-align:right" | 61 | style="text-align:right" | 98 | 158.939286(11) | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/61/159.pdf 2005] | {{val|1.648|0.043|0.042|u=s}}<ref name=Ln922>{{cite journal |last1=Kiss |first1=G. G. |last2=Vitéz-Sveiczer |first2=A. |last3=Saito |first3=Y. |display-authors=et al. |title=Measuring the β-decay properties of neutron-rich exotic Pm, Sm, Eu, and Gd isotopes to constrain the nucleosynthesis yields in the rare-earth region |journal=The Astrophysical Journal |volume=936 |issue=107 |date=2022 |page=107 |doi=10.3847/1538-4357/ac80fc|bibcode=2022ApJ...936..107K |doi-access=free |hdl=2117/375253 |hdl-access=free }}</ref><!--only half-lives updated on 2022-11-25--> | β⁻ | ¹⁵⁹Sm | (5/2−) | |-id=Promethium-159m | rowspan=2 style="text-indent:1em" | ^159mPm | rowspan=2 colspan="3" style="text-indent:2em" | 1465.0(5)&nbsp;keV | rowspan=2 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/isomers/abstracts/61/159Pm-1.pdf 2021] | rowspan=2|4.42(17)&nbsp;μs | IT | ¹⁵⁹Pm | rowspan=2|17/2+# | rowspan=2| |- | β⁻, n (<0.6%)<ref name=Ln922/> | ¹⁵⁸Sm |-id=Promethium-160 | rowspan=2|¹⁶⁰Pm | rowspan=2 style="text-align:right" | 61 | rowspan=2 style="text-align:right" | 99 | rowspan=2|159.9432153(22) | rowspan=2 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/61/160.pdf 2012] | rowspan=2|{{val|874|16|12|u=ms}}<ref name=Ln922/> | β⁻ | ¹⁶⁰Sm | rowspan=2|6−# | rowspan=2| |- | β⁻, n (<0.1%)<ref name=Ln922/> | ¹⁵⁹Sm |-id=Promethium-160m | style="text-indent:1em" | ^160mPm | colspan="3" style="text-indent:2em" | 191(11)&nbsp;keV | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/isomers/abstracts/61/160Pm-1.pdf 2020] | >700&nbsp;ms | | | 1−# | |-id=Promethium-161 | rowspan=2|¹⁶¹Pm | rowspan=2 style="text-align:right" | 61 | rowspan=2 style="text-align:right" | 100 | rowspan=2|160.9462298(97) | rowspan=2 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/61/161.pdf 2012] | rowspan=2|{{val|724|20|12|u=ms}}<ref name=Ln922/> | β⁻ (98.91%) | ¹⁶¹Sm | rowspan=2|(5/2−) | rowspan=2| |- | β⁻, n (1.09%)<ref name=Ln922/> | ¹⁶⁰Sm |-id=Promethium-161m | style="text-indent:1em" | ^161mPm | colspan="3" style="text-indent:2em" | 965.9(9)&nbsp;keV | style="text-align:center" | [https://www.nndc.bnl.gov/discovery/isomers/abstracts/61/161Pm-1.pdf 2021] | 890(90)&nbsp;ns | IT | ¹⁶¹Pm | (13/2+) | |-id=Promethium-162 | rowspan=2|¹⁶²Pm | rowspan=2 style="text-align:right" | 61 | rowspan=2 style="text-align:right" | 101 | rowspan=2|161.95057(32)# | rowspan=2 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/61/162.pdf 2012] | rowspan=2|{{val|467|38|18|u=ms}}<ref name=Ln922/> | β⁻ (98.21%) | ¹⁶²Sm | rowspan=2| 2+# | rowspan=2| |- | β⁻, n (1.79%)<ref name=Ln922/> | ¹⁶¹Sm |-id=Promethium-163 | rowspan=2|¹⁶³Pm | rowspan=2 style="text-align:right" | 61 | rowspan=2 style="text-align:right" | 102 | rowspan=2|162.95388(43)# | rowspan=2 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/61/163.pdf 2012] | rowspan=2|{{val|362|42|30|u=ms}}<ref name=Ln922/> | β⁻ (95%) | ¹⁶³Sm | rowspan=2|5/2−# | rowspan=2| |- | β⁻, n (5.00%)<ref name=Ln922/> | ¹⁶²Sm |-id=Promethium-164 | rowspan=2|¹⁶⁴Pm | rowspan=2 style="text-align:right" | 61 | rowspan=2 style="text-align:right" | 103 | rowspan=2|163.95882(43)# | rowspan=2 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/61/164.pdf 2018] | rowspan=2|{{val|280|38|33|u=ms}}<ref name=Ln922/> | β⁻ (93.82%) | ¹⁶⁴Sm | rowspan=2|5−# | rowspan=2| |- | β⁻, n (6.18%)<ref name=Ln922/> | ¹⁶³Sm |-id=Promethium-165 | rowspan=2|¹⁶⁵Pm | rowspan=2 style="text-align:right" | 61 | rowspan=2 style="text-align:right" | 104 | rowspan=2|164.96278(54)# | rowspan=2 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/61/165.pdf 2018] | rowspan=2|{{val|297|111|101|u=ms}}<ref name=Ln922/> | β⁻ (86.74%) | ¹⁶⁵Sm | rowspan=2|5/2−# | rowspan=2| |- | β⁻, n (13.26%)<ref name=Ln922/> | ¹⁶⁴Sm |-id=Promethium-166 | rowspan=2|¹⁶⁶Pm | rowspan=2 style="text-align:right" | 61 | rowspan=2 style="text-align:right" | 105 | rowspan=2| | rowspan=2 style="text-align:center" | [https://www.nndc.bnl.gov/discovery/abstracts/61/166.pdf 2022] | rowspan=2|{{val|228|131|112|u=ms}}<ref name=Ln922/> | β⁻ | ¹⁶⁶Sm | rowspan=2| | rowspan=2| |- | β⁻, n (<52%)<ref name=Ln922/> | ¹⁶⁵Sm {{Isotopes table/footer}}

==Stability of promethium isotopes== {{See also|Isotopes of technetium#Stability of technetium isotopes}} Promethium is one of the two elements of the first 82 elements that has no stable isotopes. This is a rarely occurring effect of the liquid drop model. Namely, promethium does not have any beta-stable isotopes, as for any mass number, it is energetically favorable for a promethium isotope to undergo positron emission or beta decay, respectively forming a neodymium or samarium isotope which has a higher binding energy per nucleon. The other element for which this happens is technetium (''Z''&nbsp;=&nbsp;43).

== Promethium-147 == Promethium-147 beta decays to the long-lived primordial radioisotope samarium-147 with a half-life of 2.6234 years, emitting low-energy beta radiation without gamma emission. It is a common fission product, produced in nuclear reactors and in trace quantities in nature, where it is also produced by the alpha decay of europium-151.<ref>{{cite journal |last1=Belli |first1=P. |last2=Bernabei |first2=R. |last3=Cappella |first3=F. |last4=Cerulli |first4=R. |last5=Dai |first5=C. J. |last6=Danevich |first6=F. A. |last7=D'Angelo |first7=A. |last8=Incicchitti |first8=A. |last9=Kobychev |first9=V. V. |title=Search for α decay of natural Europium |year=2007 |journal=Nuclear Physics A |volume=789 |issue=1–4 |pages=15–29 |doi=10.1016/j.nuclphysa.2007.03.001 |bibcode=2007NuPhA.789...15B |display-authors=3}}</ref>

In the reactor environment, it is almost exclusively produced through beta decay of neodymium-147 as usual for fission products. The isotopes ^142-146Nd, ¹⁴⁸Nd, and ¹⁵⁰Nd are all stable with respect to beta decay, so the isotopes of promethium with those masses are not produced by beta decay and are therefore not significant fission products (as they could only be produced directly, rather than through a beta-decay chain). ¹⁴⁹Pm and ¹⁵¹Pm are, but have half-lives of only 53.08 and 28.40 hours, so are not found in spent nuclear fuel that has been cooled for months or years.

Promethium-147 is used as a beta particle source and a radioisotope thermoelectric generator (RTG) fuel; its power density is about 2 watts per gram. Mixed with a phosphor, it was used to illuminate the Apollo Lunar Module electrical switch tips and the control panels of the Lunar Roving Vehicle.<ref>{{cite web|title=Apollo Experience Report - Protection Against Radiation|url=http://www.hq.nasa.gov/alsj/tnD7080RadProtect.pdf|publisher=NASA|access-date=9 December 2011|archive-url=https://web.archive.org/web/20141114112051/http://www.hq.nasa.gov/alsj/tnD7080RadProtect.pdf|archive-date=14 November 2014|url-status=dead}}</ref> For luminescent applications, it has generally been replaced by tritium, which is even safer and has a longer half-life (12.32 years).

== See also == '''Daughter products other than promethium''' * Isotopes of samarium * Isotopes of neodymium * Isotopes of praseodymium

== References == {{Reflist}}

{{Navbox element isotopes}}

Category:Isotopes of promethium Category:Promethium Promethium