# Isotopes of praseodymium

Naturally occurring praseodymium ($_{59}$Pr) is composed of one stable isotope, $^{141}$Pr. Thirty-eight radioisotopes have been characterized with the most stable being $^{143}$Pr, with a half-life of 13.57 days and $^{142}$Pr, with a half-life of 19.12 hours. All of the remaining radioactive isotopes have half-lives that are less than six hours and the majority of these have half-lives that are less than 33 seconds. This element also has 15 meta states with the most stable being $^{138m}$Pr (t$_{1/2}$ 2.12 hours), $^{142m}$Pr (t$_{1/2}$ 14.6 minutes) and $^{134m}$Pr (t$_{1/2}$ 11 minutes).
The isotopes of praseodymium range in atomic weight from 120.955 u ($^{121}$Pr) to 158.955 u ($^{159}$Pr). The primary decay mode before the stable isotope, $^{141}$Pr, is electron capture and the mode after is beta decay. The primary decay products before $^{141}$Pr are element 58 (cerium) isotopes and the primary products after are element 60 (neodymium) isotopes.

## List of isotopes

| Nuclide | Z | N | Isotopic mass (Da) | Half-life | Decay mode | Daughter isotope | Spin and parity | Isotopic abundance |
| Isotopic abundance |||
| $^{121}$Pr | 59 | 62 | 120.95539(54)# | 12(5) ms | p | $^{120}$Ce | (3/2)(+#) | |
| $^{124}$Pr | 59 | 65 | 123.94294(43)# | 1.2(2) s | β$^+$ | $^{124}$Ce | | |
| $^{124}$Pr | 59 | 65 | 123.94294(43)# | 1.2(2) s | β$^+$, p (?%) | $^{123}$La | | |
| $^{125}$Pr | 59 | 66 | 124.93766(32)# | 3.3(7) s | β$^+$ | $^{125}$Ce | 3/2+# | |
| $^{126}$Pr | 59 | 67 | 125.93524(21)# | 3.12(18) s | β$^+$ | $^{126}$Ce | (4, 5) | |
| $^{126}$Pr | 59 | 67 | 125.93524(21)# | 3.12(18) s | β$^+$, p (?%) | $^{125}$La | (4, 5) | |
| $^{127}$Pr | 59 | 68 | 126.93071(21)# | 4.2(3) s | β$^+$ | $^{127}$Ce | 3/2+# | |
| $^{127m}$Pr | 600(200)# keV | 600(200)# keV | 600(200)# keV | 2# μs | | | (11/2−) | |
| $^{128}$Pr | 59 | 69 | 127.928791(32) | 2.85(9) s | β$^+$ | $^{128}$Ce | (3+) | |
| $^{128}$Pr | 59 | 69 | 127.928791(32) | 2.85(9) s | β$^+$, p (?%) | $^{127}$La | (3+) | |
| $^{129}$Pr | 59 | 70 | 128.925095(32) | 30(4) s | β$^+$ | $^{129}$Ce | (3/2+) | |
| $^{129m}$Pr | 382.57(24) keV | 382.57(24) keV | 382.57(24) keV | 26(11)# μs | IT | $^{129}$Pr | (11/2−) | |
| $^{130}$Pr | 59 | 71 | 129.923590(69) | 40.0(4) s | β$^+$ | $^{130}$Ce | (6, 7)(+#) | |
| $^{130m}$Pr | 100(100)# keV | 100(100)# keV | 100(100)# keV | 10# s | | | 2+# | |
| $^{131}$Pr | 59 | 72 | 130.920235(50) | 1.50(3) min | β$^+$ | $^{131}$Ce | (3/2+) | |
| $^{131m}$Pr | 152.4(3) keV | 152.4(3) keV | 152.4(3) keV | 5.73(20) s | IT (96.4%) | $^{131}$Pr | (11/2−) | |
| $^{131m}$Pr | 152.4(3) keV | 152.4(3) keV | 152.4(3) keV | 5.73(20) s | β$^+$ (3.6%) | $^{131}$Ce | (11/2−) | |
| $^{132}$Pr | 59 | 73 | 131.919240(31) | 1.49(11) min | β$^+$ | $^{132}$Ce | (2+) | |
| $^{132m1}$Pr | 30(30)# keV | 30(30)# keV | 30(30)# keV | 1# s | | | (5+) | |
| $^{132m2}$Pr | 250(30)# keV | 250(30)# keV | 250(30)# keV | 2.46(4) μs | IT | $^{132}$Pr | (8+) | |
| $^{132m3}$Pr | 300(30)# keV | 300(30)# keV | 300(30)# keV | 486(70) ns | IT | $^{132}$Pr | (8−) | |
| $^{133}$Pr | 59 | 74 | 132.916331(13) | 6.5(3) min | β$^+$ | $^{133}$Ce | 5/2+ | |
| $^{133m}$Pr | 192.12(14) keV | 192.12(14) keV | 192.12(14) keV | 1.1(2) μs | IT | $^{133}$Pr | (11/2−) | |
| $^{134}$Pr | 59 | 75 | 133.915697(22) | 17(2) min | β$^+$ | $^{134}$Ce | 2− | |
| $^{134m}$Pr | 67.7(4) keV | 67.7(4) keV | 67.7(4) keV | ~11 min | β$^+$ | $^{134}$Ce | 6− | |
| $^{135}$Pr | 59 | 76 | 134.913112(13) | 24(1) min | β$^+$ | $^{135}$Ce | 3/2+ | |
| $^{135m}$Pr | 358.06(6) keV | 358.06(6) keV | 358.06(6) keV | 105(10) μs | IT | $^{135}$Pr | (11/2−) | |
| $^{136}$Pr | 59 | 77 | 135.912677(12) | 13.1(1) min | β$^+$ | $^{136}$Ce | 2+ | |
| $^{137}$Pr | 59 | 78 | 136.9106792(87) | 1.28(3) h | β$^+$ | $^{137}$Ce | 5/2+ | |
| $^{137m}$Pr | 561.22(23) keV | 561.22(23) keV | 561.22(23) keV | 2.66(7) μs | IT | $^{137}$Pr | 11/2− | |
| $^{138}$Pr | 59 | 79 | 137.910757(11) | 1.45(5) min | β$^+$ | $^{138}$Ce | 1+ | |
| $^{138m}$Pr | 350(19) keV | 350(19) keV | 350(19) keV | 2.12(4) h | β$^+$ | $^{138}$Ce | 7− | |
| $^{139}$Pr | 59 | 80 | 138.9089327(39) | 4.41(4) h | β$^+$ | $^{139}$Ce | 5/2+ | |
| $^{140}$Pr | 59 | 81 | 139.9090856(66) | 3.39(1) min | EC (51.3%) | $^{140}$Ce | 1+ | |
| $^{140}$Pr | 59 | 81 | 139.9090856(66) | 3.39(1) min | β$^+$ (48.7%) | $^{140}$Ce | 1+ | |
| $^{140m1}$Pr | 127.8(3) keV | 127.8(3) keV | 127.8(3) keV | 0.35(2) μs | IT | $^{140}$Pr | 5+ | |
| $^{140m2}$Pr | 763.7(5) keV | 763.7(5) keV | 763.7(5) keV | 3.05(20) μs | IT | $^{140}$Pr | (7)− | |
| $^{141}$Pr | 59 | 82 | 140.9076596(16) | Stable | Stable | Stable | 5/2+ | 1.0000 |
| $^{142}$Pr | 59 | 83 | 141.9100516(16) | 19.12(4) h | β$^−$ (99.98%) | $^{142}$Nd | 2− | |
| $^{142}$Pr | 59 | 83 | 141.9100516(16) | 19.12(4) h | EC (0.0164%) | $^{142}$Ce | 2− | |
| $^{142m}$Pr | 3.694(3) keV | 3.694(3) keV | 3.694(3) keV | 14.6(5) min | IT | $^{142}$Pr | 5− | |
| $^{143}$Pr | 59 | 84 | 142.9108226(19) | 13.57(2) d | β$^−$ | $^{143}$Nd | 7/2+ | |
| $^{144}$Pr | 59 | 85 | 143.9133107(29) | 17.28(5) min | β$^−$ | $^{144}$Nd | 0− | |
| $^{144m}$Pr | 59.03(3) keV | 59.03(3) keV | 59.03(3) keV | 7.2(3) min | IT (~99.93%) | $^{144}$Pr | 3− | |
| $^{144m}$Pr | 59.03(3) keV | 59.03(3) keV | 59.03(3) keV | 7.2(3) min | β$^−$ (~0.07%) | $^{144}$Nd | 3− | |
| $^{145}$Pr | 59 | 86 | 144.9145180(77) | 5.984(10) h | β$^−$ | $^{145}$Nd | 7/2+ | |
| $^{146}$Pr | 59 | 87 | 145.917688(37) | 24.09(10) min | β$^−$ | $^{146}$Nd | (2−) | |
| $^{147}$Pr | 59 | 88 | 146.919007(17) | 13.39(4) min | β$^−$ | $^{147}$Nd | 3/2+ | |
| $^{148}$Pr | 59 | 89 | 147.922130(16) | 2.29(2) min | β$^−$ | $^{148}$Nd | 1− | |
| $^{148m}$Pr | 76.80(20) keV | 76.80(20) keV | 76.80(20) keV | 2.01(7) min | β$^−$ (64%) | $^{148}$Nd | (4) | |
| $^{148m}$Pr | 76.80(20) keV | 76.80(20) keV | 76.80(20) keV | 2.01(7) min | IT (36%) | $^{148}$Pr | (4) | |
| $^{149}$Pr | 59 | 90 | 148.923736(11) | 2.26(7) min | β$^−$ | $^{149}$Nd | (5/2+) | |
| $^{150}$Pr | 59 | 91 | 149.9266764(97) | 6.19(16) s | β$^−$ | $^{150}$Nd | 1− | |
| $^{151}$Pr | 59 | 92 | 150.928309(13) | 18.90(7) s | β$^−$ | $^{151}$Nd | (3/2−) | |
| $^{151m}$Pr | 35.10(10) keV | 35.10(10) keV | 35.10(10) keV | 50(8) μs | IT | $^{151}$Pr | (7/2+) | |
| $^{152}$Pr | 59 | 93 | 151.931553(20) | 3.57(11) s | β$^−$ | $^{152}$Nd | 4+ | |
| $^{152m}$Pr | 115.1(3) keV | 115.1(3) keV | 115.1(3) keV | 4.16(10) μs | IT | $^{152}$Pr | (1+) | |
| $^{153}$Pr | 59 | 94 | 152.933904(13) | 4.28(11) s | β$^−$ | $^{153}$Nd | 3/2−# | |
| $^{154}$Pr | 59 | 95 | 153.93789(11) | 2.30(9) s | β$^−$ | $^{154}$Nd | (3+) | |
| $^{155}$Pr | 59 | 96 | 154.940509(18) | 1.47(3) s | β$^−$ | $^{155}$Nd | 3/2−# | |
| $^{156}$Pr | 59 | 97 | 155.9447669(11) | 444(6) ms | β$^−$ | $^{156}$Nd | 1+# | |
| $^{157}$Pr | 59 | 98 | 156.9480031(34) | 307(21) ms | β$^−$ | $^{157}$Nd | 3/2−# | |
| $^{158}$Pr | 59 | 99 | 157.95260(32)# | 181(14) ms | β$^−$ | $^{158}$Nd | 5−# | |
| $^{159}$Pr | 59 | 100 | 158.95623(43)# | 134(43) ms | β$^−$ | $^{159}$Nd | 3/2−# | |
| $^{160}$Pr | 59 | 101 | 159.96114(43)# | 170(140) ms | β$^−$ | $^{160}$Nd | 1+# | |
| $^{161}$Pr | 59 | 102 | 160.96512(54)# | 90# ms [>550 ns] | | | 3/2−# | |
| This table header & footer: view |||||||||
* ↑ $^m$Pr – Excited nuclear isomer.
* ↑ ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
* ↑ # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
* 1 2 3 # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
* ↑ Modes of decay: EC:Electron capture IT:Isomeric transition p:Proton emission
* ↑ Bold italics symbol as daughter – Daughter product is nearly stable.
* ↑ Bold symbol as daughter – Daughter product is stable.
* ↑ ( ) spin value – Indicates spin with weak assignment arguments.
* ↑ Order of ground state and isomer is uncertain.
* 1 2 Fission product