# Isotopes of holmium

Natural holmium ($_{67}$Ho) contains one observationally stable isotope, $^{165}$Ho. The below table lists 39 isotopes spanning $^{140}$Ho through $^{178}$Ho as well as 40 nuclear isomers. Among the known synthetic radioactive isotopes; the most stable one is $^{163}$Ho, with a half-life of 4,570 years. All other radioisotopes have half-lives not greater than 1.117 days in their ground states (although the metastable $^{166m1}$Ho has a half-life of about 1,200 years), and most have half-lives under 3 hours.

## List of isotopes

| Nuclide | Z | N | Isotopic mass (Da) | Half-life | Decay mode | Daughter isotope | Spin and parity | Isotopic abundance |
| Isotopic abundance |||
| $^{140}$Ho | 67 | 73 | 139.96853(54)# | 6(3) ms | p | $^{139}$Dy | 8+# | |
| $^{141}$Ho | 67 | 74 | 140.96311(43)# | 4.1(1) ms | p | $^{140}$Dy | (7/2−) | |
| $^{141m}$Ho | 66(2) keV | 66(2) keV | 66(2) keV | 7.3(3) μs | p | $^{140}$Dy | (1/2+) | |
| $^{142}$Ho | 67 | 75 | 141.96001(43)# | 400(100) ms | β$^+$ | $^{142}$Dy | (7−, 8+) | |
| $^{142}$Ho | 67 | 75 | 141.96001(43)# | 400(100) ms | β$^+$, p (?%) | $^{141}$Tb | (7−, 8+) | |
| $^{142}$Ho | 67 | 75 | 141.96001(43)# | 400(100) ms | p (?%) | $^{141}$Dy | (7−, 8+) | |
| $^{143}$Ho | 67 | 76 | 142.95486(32)# | 300# ms [>200 ns] | | | 11/2−# | |
| $^{144}$Ho | 67 | 77 | 143.9521097(91) | 0.7(1) s | β$^+$ | $^{144}$Dy | (5−) | |
| $^{144}$Ho | 67 | 77 | 143.9521097(91) | 0.7(1) s | β$^+$, p (?%) | $^{143}$Tb | (5−) | |
| $^{144m}$Ho | 265.3(3) keV | 265.3(3) keV | 265.3(3) keV | 519(5) ns | IT | $^{144}$Ho | (8+) | |
| $^{145}$Ho | 67 | 78 | 144.9472674(80) | 2.4(1) s | β$^+$ | $^{145}$Dy | (11/2−) | |
| $^{146}$Ho | 67 | 79 | 145.9449935(71) | 3.32(22) s | β$^+$ | $^{146}$Dy | (6−) | |
| $^{146}$Ho | 67 | 79 | 145.9449935(71) | 3.32(22) s | β$^+$, p (?%) | $^{145}$Tb | (6−) | |
| $^{147}$Ho | 67 | 80 | 146.9401423(54) | 5.8(4) s | β$^+$ | $^{147}$Dy | (11/2−) | |
| $^{147m}$Ho | 2687.1(4) keV | 2687.1(4) keV | 2687.1(4) keV | 315(30) ns | IT | $^{147}$Ho | (27/2−) | |
| $^{148}$Ho | 67 | 81 | 147.937744(90) | 2.2(11) s | β$^+$ | $^{148}$Dy | (1+) | |
| $^{148m1}$Ho | 250(100)# keV | 250(100)# keV | 250(100)# keV | 9.49(12) s | β$^+$ (99.92%) | $^{148}$Dy | (5−) | |
| $^{148m1}$Ho | 250(100)# keV | 250(100)# keV | 250(100)# keV | 9.49(12) s | β$^+$, p (0.08%) | $^{147}$Tb | (5−) | |
| $^{148m2}$Ho | 940(100)# keV | 940(100)# keV | 940(100)# keV | 2.36(6) ms | IT | $^{148m1}$Ho | (10)+ | |
| $^{149}$Ho | 67 | 82 | 148.933820(13) | 21.1(2) s | β$^+$ | $^{149}$Dy | (11/2−) | |
| $^{149m}$Ho | 48.80(20) keV | 48.80(20) keV | 48.80(20) keV | 56(3) s | β$^+$ | $^{149}$Dy | (1/2+) | |
| $^{150}$Ho | 67 | 83 | 149.933498(15) | 76.8(18) s | β$^+$ | $^{150}$Dy | (2)− | |
| $^{150m1}$Ho | 0(50) keV | 0(50) keV | 0(50) keV | 23.3(3) s | β$^+$ | $^{150}$Dy | (9)+ | |
| $^{150m2}$Ho | 7900(50) keV | 7900(50) keV | 7900(50) keV | 787(36) ns | IT | $^{150}$Ho | (28−) | |
| $^{151}$Ho | 67 | 84 | 150.9316982(89) | 35.2(1) s | β$^+$ (78%) | $^{151}$Dy | 11/2− | |
| $^{151}$Ho | 67 | 84 | 150.9316982(89) | 35.2(1) s | α (22%) | $^{147}$Tb | 11/2− | |
| $^{151m}$Ho | 41.0(2) keV | 41.0(2) keV | 41.0(2) keV | 47.2(13) s | α (77%) | $^{147}$Tb | 1/2+ | |
| $^{151m}$Ho | 41.0(2) keV | 41.0(2) keV | 41.0(2) keV | 47.2(13) s | β$^+$ (23%) | $^{151}$Dy | 1/2+ | |
| $^{152}$Ho | 67 | 85 | 151.931718(13) | 161.8(3) s | β$^+$ (88%) | $^{152}$Dy | 2− | |
| $^{152}$Ho | 67 | 85 | 151.931718(13) | 161.8(3) s | α (12%) | $^{148}$Tb | 2− | |
| $^{152m1}$Ho | 160(3) keV | 160(3) keV | 160(3) keV | 49.8(2) s | β$^+$ (89.2%) | $^{152}$Dy | 9+ | |
| $^{152m1}$Ho | 160(3) keV | 160(3) keV | 160(3) keV | 49.8(2) s | α (10.8%) | $^{148}$Tb | 9+ | |
| $^{152m2}$Ho | 3019.59(19) keV | 3019.59(19) keV | 3019.59(19) keV | 8.4(3) μs | IT | $^{152}$Ho | 19− | |
| $^{153}$Ho | 67 | 86 | 152.9302067(54) | 2.01(3) min | β$^+$ (99.95%) | $^{153}$Dy | 11/2− | |
| $^{153}$Ho | 67 | 86 | 152.9302067(54) | 2.01(3) min | α (0.051%) | $^{149}$Tb | 11/2− | |
| $^{153m1}$Ho | 68.7(3) keV | 68.7(3) keV | 68.7(3) keV | 9.3(5) min | β$^+$ (99.82%) | $^{153}$Dy | 1/2+ | |
| $^{153m1}$Ho | 68.7(3) keV | 68.7(3) keV | 68.7(3) keV | 9.3(5) min | α (0.18%) | $^{149}$Tb | 1/2+ | |
| $^{153m2}$Ho | 2772.3(14) keV | 2772.3(14) keV | 2772.3(14) keV | 229(2) ns | IT | $^{153}$Ho | 31/2+ | |
| $^{154}$Ho | 67 | 87 | 153.9306068(88) | 11.76(19) min | β$^+$ (99.98%) | $^{154}$Dy | 2− | |
| $^{154}$Ho | 67 | 87 | 153.9306068(88) | 11.76(19) min | α (0.019%) | $^{150}$Tb | 2− | |
| $^{154m}$Ho | 243(28) keV | 243(28) keV | 243(28) keV | 3.10(14) min | β$^+$ | $^{154}$Dy | 8+ | |
| $^{154m}$Ho | 243(28) keV | 243(28) keV | 243(28) keV | 3.10(14) min | α (<0.001%) | $^{150}$Tb | 8+ | |
| $^{154m}$Ho | 243(28) keV | 243(28) keV | 243(28) keV | 3.10(14) min | IT (rare) | $^{154}$Ho | 8+ | |
| $^{155}$Ho | 67 | 88 | 154.929103(19) | 48(2) min | β$^+$ | $^{155}$Dy | 5/2+ | |
| $^{155m}$Ho | 141.87(11) keV | 141.87(11) keV | 141.87(11) keV | 880(80) μs | IT | $^{155}$Ho | 11/2− | |
| $^{156}$Ho | 67 | 89 | 155.929642(41) | 56(1) min | β$^+$ | $^{156}$Dy | 4− | |
| $^{156m1}$Ho | 52.37(30) keV | 52.37(30) keV | 52.37(30) keV | 9.5(15) s | IT | $^{156}$Ho | 1− | |
| $^{156m2}$Ho | 230(50) keV | 230(50) keV | 230(50) keV | 7.6(3) min | β$^+$ (75%) | $^{156}$Dy | 9+ | |
| $^{156m2}$Ho | 230(50) keV | 230(50) keV | 230(50) keV | 7.6(3) min | IT (25%) | $^{156}$Ho | 9+ | |
| $^{157}$Ho | 67 | 90 | 156.928252(25) | 12.6(2) min | β$^+$ | $^{157}$Dy | 7/2− | |
| $^{158}$Ho | 67 | 91 | 157.928945(29) | 11.3(4) min | β$^+$ | $^{158}$Dy | 5+ | |
| $^{158m1}$Ho | 67.20(1) keV | 67.20(1) keV | 67.20(1) keV | 28(2) min | IT (91%) | $^{158}$Ho | 2− | |
| $^{158m1}$Ho | 67.20(1) keV | 67.20(1) keV | 67.20(1) keV | 28(2) min | β$^+$ (9%) | $^{158}$Dy | 2− | |
| $^{158m2}$Ho | 91.595(12) keV | 91.595(12) keV | 91.595(12) keV | 140(25) ns | IT | $^{158}$Ho | (2−) | |
| $^{158m3}$Ho | 180(70)# keV | 180(70)# keV | 180(70)# keV | 21.3(23) min | β$^+$ | $^{158}$Dy | (9+) | |
| $^{159}$Ho | 67 | 92 | 158.9277187(33) | 33.05(11) min | β$^+$ | $^{159}$Dy | 7/2− | |
| $^{159m}$Ho | 205.91(5) keV | 205.91(5) keV | 205.91(5) keV | 8.30(8) s | IT | $^{159}$Ho | 1/2+ | |
| $^{160}$Ho | 67 | 93 | 159.928736(16) | 25.6(3) min | β$^+$ | $^{160}$Dy | 5+ | |
| $^{160m1}$Ho | 59.98(3) keV | 59.98(3) keV | 59.98(3) keV | 5.02(5) h | IT (73%) | $^{160}$Ho | 2− | |
| $^{160m1}$Ho | 59.98(3) keV | 59.98(3) keV | 59.98(3) keV | 5.02(5) h | β$^+$ (27%) | $^{160}$Dy | 2− | |
| $^{160m2}$Ho | 197(16) keV | 197(16) keV | 197(16) keV | ~3 s | IT | $^{160}$Ho | (9+) | |
| $^{161}$Ho | 67 | 94 | 160.9278618(23) | 2.48(5) h | EC | $^{161}$Dy | 7/2− | |
| $^{161m}$Ho | 211.15(3) keV | 211.15(3) keV | 211.15(3) keV | 6.76(7) s | IT | $^{161}$Ho | 1/2+ | |
| $^{162}$Ho | 67 | 95 | 161.9291025(33) | 15.0(10) min | β$^+$ | $^{162}$Dy | 1+ | |
| $^{162m}$Ho | 105.87(6) keV | 105.87(6) keV | 105.87(6) keV | 67.0(7) min | IT (62%) | $^{162}$Ho | 6− | |
| $^{162m}$Ho | 105.87(6) keV | 105.87(6) keV | 105.87(6) keV | 67.0(7) min | β$^+$ (38%) | $^{162}$Dy | 6− | |
| $^{163}$Ho | 67 | 96 | 162.92874026(74) | 4570(25) y | EC | $^{163}$Dy | 7/2− | |
| $^{163m1}$Ho | 297.88(7) keV | 297.88(7) keV | 297.88(7) keV | 1.09(3) s | IT | $^{163}$Ho | 1/2+ | |
| $^{163m2}$Ho | 2109.4(4) keV | 2109.4(4) keV | 2109.4(4) keV | 800(150) ns | IT | $^{163}$Ho | (23/2+) | |
| $^{164}$Ho | 67 | 97 | 163.9302405(15) | 28.8(5) min | EC (61%) | $^{164}$Dy | 1+ | |
| $^{164}$Ho | 67 | 97 | 163.9302405(15) | 28.8(5) min | β$^−$ (39%) | $^{164}$Er | 1+ | |
| $^{164m}$Ho | 139.78(7) keV | 139.78(7) keV | 139.78(7) keV | 36.6(3) min | IT | $^{164}$Ho | 6− | |
| $^{165}$Ho | 67 | 98 | 164.93032912(84) | Observationally Stable | Observationally Stable | Observationally Stable | 7/2− | 1.0000 |
| $^{165m1}$Ho | 361.675(11) keV | 361.675(11) keV | 361.675(11) keV | 1.512(4) μs | IT | $^{165}$Ho | 3/2+ | |
| $^{165m2}$Ho | 715.33(2) keV | 715.33(2) keV | 715.33(2) keV | <100 ns | IT | $^{165}$Ho | 7/2+ | |
| $^{166}$Ho | 67 | 99 | 165.93229121(84) | 26.812(7) h | β$^−$ | $^{166}$Er | 0− | |
| $^{166m1}$Ho | 5.969(12) keV | 5.969(12) keV | 5.969(12) keV | 1132.6(39) y | β$^−$ | $^{166}$Er | 7− | |
| $^{166m2}$Ho | 190.9021(20) keV | 190.9021(20) keV | 190.9021(20) keV | 185(15) μs | IT | $^{166}$Ho | 3+ | |
| $^{167}$Ho | 67 | 100 | 166.9331403(56) | 3.1(1) h | β$^−$ | $^{167}$Er | 7/2− | |
| $^{167m}$Ho | 259.34(11) keV | 259.34(11) keV | 259.34(11) keV | 6.0(10) μs | IT | $^{167}$Ho | 3/2+ | |
| $^{168}$Ho | 67 | 101 | 167.935524(32) | 2.99(7) min | β$^−$ | $^{168}$Er | 3+ | |
| $^{168m1}$Ho | 59(1) keV | 59(1) keV | 59(1) keV | 132(4) s | IT | $^{168}$Ho | (6+) | |
| $^{168m2}$Ho | 143.43(17) keV | 143.43(17) keV | 143.43(17) keV | >4 μs | IT | $^{168}$Ho | (1)− | |
| $^{168m3}$Ho | 192.57(20) keV | 192.57(20) keV | 192.57(20) keV | 108(11) ns | IT | $^{168}$Ho | 1+ | |
| $^{169}$Ho | 67 | 102 | 168.936880(22) | 4.72(10) min | β$^−$ | $^{169}$Er | 7/2− | |
| $^{169m}$Ho | 1386.2(4) keV | 1386.2(4) keV | 1386.2(4) keV | 118(6) μs | IT | $^{169}$Ho | (19/2+) | |
| $^{170}$Ho | 67 | 103 | 169.939627(54) | 2.76(5) min | β$^−$ | $^{170}$Er | (6+) | |
| $^{170m}$Ho | 100(80) keV | 100(80) keV | 100(80) keV | 43(2) s | β$^−$ | $^{170}$Er | (1+) | |
| $^{171}$Ho | 67 | 104 | 170.94147(64) | 53(2) s | β$^−$ | $^{171}$Er | 7/2−# | |
| $^{172}$Ho | 67 | 105 | 171.94473(21)# | 25(3) s | β$^−$ | $^{172}$Er | 0+# | |
| $^{173}$Ho | 67 | 106 | 172.94702(32)# | 7.1(4) s | β$^−$ | $^{173}$Er | 7/2−# | |
| $^{173m}$Ho | 405(1) keV | 405(1) keV | 405(1) keV | 3.7(12) μs | IT | $^{173}$Ho | 1/2+# | |
| $^{174}$Ho | 67 | 107 | 173.95076(32)# | 3.7(4) s | β$^−$ | $^{174}$Er | (8−) | |
| $^{175}$Ho | 67 | 108 | 174.95352(43)# | 1.88(55) s | β$^−$ | $^{175}$Er | 7/2−# | |
| $^{176}$Ho | 67 | 109 | 175.95771(54)# | 1# s [>300 ns] | | | 4+# | |
| $^{177}$Ho | 67 | 110 | 176.96105(54)# | 1# s [>550 ns] | β$^−$ | $^{177}$Er | 7/2−# | |
| $^{178}$Ho | 67 | 111 | 177.96551(54)# | 750# ms [>550 ns] | | | 2+# | |
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* ↑ $^m$Ho – 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
* ↑ Bold symbol as daughter – Daughter product is stable.
* ↑ ( ) spin value – Indicates spin with weak assignment arguments.
* 1 2 Order of ground state and isomer is uncertain.
* ↑ Believed to undergo α decay to $^{161}$Tb