Isotopes of holmium

Template:Infobox holmium isotopes

Holmium-166m1 oxide

Natural holmium (67Ho) contains one observationally stable isotope, 165Ho. The known isotopes of holmium range from 140Ho to 175Ho. The primary decay mode before the stable 165Ho, is beta plus decay to dysprosium isotopes, and the primary mode after is beta minus decay to erbium isotopes.

Among the synthetic radioactive isotopes the most stable is 163Ho with a half-life of 4,570 years, the next most stable is 166Ho having a half-life of 26.812 hours, and others are under 4 hours. The isomeric nuclide 166m1Ho, however, has a half-life of 1,133 years, much the longest of the meta states.

Holmium-166 (ground state) has been studied for medical application.[1][2]

## List of isotopes

Nuclide
[n 1] | Z | N | Isotopic mass (u)
[n 2][n 3] | Half-life
[n 4] | Decay
mode
[n 5] | Daughter
isotope
[n 6] | Spin and
parity
[n 7][n 4] | Physics:Natural abundance (mole fraction)

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Excitation energy[n 4] | Normal proportion  | Range of variation
140Ho  | 67  | 73  | 139.96853(54)#  | 6(3) ms  | p | 139Dy  | 8+#  |
141Ho  | 67  | 74  | 140.96311(43)#  | 4.1(1) ms  | p  | 140Dy  | (7/2−)  |
141mHo  | 66(2) keV  | 7.3(3) μs  | p  | 140Dy  | (1/2+)  |
142Ho  | 67  | 75  | 141.96001(43)#  | 400(100) ms  | β+ | 142Dy  | (7−, 8+)  |
β+, p (?%)  | 141Tb
p (?%)  | 141Dy
143Ho[3] | 67  | 76  | 142.95486(32)#  | 300# ms
[>310 ns]  |  |  | 11/2−#  |
144Ho  | 67  | 77  | 143.9521097(91)  | 0.7(1) s  | β+ | 144Dy  | (5−)  |
β+, p (?%)  | 143Tb
144mHo  | 265.3(3) keV  | 519(5) ns  | IT  | 144Ho  | (8+)  |
145Ho  | 67  | 78  | 144.9472674(80)  | 2.4(1) s  | β+ | 145Dy  | (11/2−)  |
146Ho  | 67  | 79  | 145.9449935(71)  | 3.32(22) s  | β+ | 146Dy  | (6−)  |
β+, p (?%)  | 145Tb
147Ho  | 67  | 80  | 146.9401423(54)  | 5.8(4) s  | β+ | 147Dy  | (11/2−)  |
147mHo  | 2687.1(4) keV  | 315(30) ns  | IT  | 147Ho  | (27/2−)  |
148Ho  | 67  | 81  | 147.937744(90)  | 2.2(11) s  | β+ | 148Dy  | (1+)  |
148m1Ho  | 250(100)# keV  | 9.49(12) s  | β+ (99.92%)  | 148Dy  | (5−)  |
β+, p (0.08%)  | 147Tb
148m2Ho  | 940(100)# keV  | 2.36(6) ms  | IT  | 148m1Ho  | (10)+  |
149Ho  | 67  | 82  | 148.933820(13)  | 21.1(2) s  | β+ | 149Dy  | (11/2−)  |
149mHo  | 48.80(20) keV  | 56(3) s  | β+ | 149Dy  | (1/2+)  |
150Ho  | 67  | 83  | 149.933498(15)  | 76.8(18) s  | β+ | 150Dy  | (2)−  |
150m1Ho[n 8] | 0(50) keV  | 23.3(3) s  | β+ | 150Dy  | (9)+  |
150m2Ho  | 7900(50) keV  | 787(36) ns  | IT  | 150Ho  | (28−)  |
151Ho  | 67  | 84  | 150.9316982(89)  | 35.2(1) s  | β+ (78%)  | 151Dy  | 11/2−  |
α (22%)  | 147Tb
151mHo  | 41.0(2) keV  | 47.2(13) s  | α (77%)  | 147Tb  | 1/2+  |
β+ (23%)  | 151Dy
152Ho  | 67  | 85  | 151.931718(13)  | 161.8(3) s  | β+ (88%)  | 152Dy  | 2−  |
α (12%)  | 148Tb
152m1Ho  | 160(3) keV  | 49.8(2) s  | β+ (89.2%)  | 152Dy  | 9+  |
α (10.8%)  | 148Tb
152m2Ho  | 3019.59(19) keV  | 8.4(3) μs  | IT  | 152Ho  | 19−  |
153Ho  | 67  | 86  | 152.9302067(54)  | 2.01(3) min  | β+ (99.95%)  | 153Dy  | 11/2−  |
α (0.051%)  | 149Tb
153m1Ho  | 68.7(3) keV  | 9.3(5) min  | β+ (99.82%)  | 153Dy  | 1/2+  |
α (0.18%)  | 149Tb
153m2Ho  | 2772.3(14) keV  | 229(2) ns  | IT  | 153Ho  | 31/2+  |
154Ho  | 67  | 87  | 153.9306068(88)  | 11.76(19) min  | β+ (99.98%)  | 154Dy  | 2−  |
α (0.019%)  | 150Tb
154mHo  | 243(28) keV  | 3.10(14) min  | β+ | 154Dy  | 8+  |
α (<0.001%)  | 150Tb
IT (rare)  | 154Ho
155Ho  | 67  | 88  | 154.929103(19)  | 48(2) min  | β+ | 155Dy  | 5/2+  |
155mHo  | 141.87(11) keV  | 880(80) μs  | IT  | 155Ho  | 11/2−  |
156Ho  | 67  | 89  | 155.929642(41)  | 56(1) min  | β+ | 156Dy | 4−  |
156m1Ho  | 52.37(30) keV  | 9.5(15) s  | IT  | 156Ho  | 1−  |
156m2Ho  | 230(50) keV  | 7.6(3) min  | β+ (75%)  | 156Dy | 9+  |
IT (25%)  | 156Ho
157Ho  | 67  | 90  | 156.928252(25)  | 12.6(2) min  | β+ | 157Dy  | 7/2−  |
158Ho  | 67  | 91  | 157.928945(29)  | 11.3(4) min  | β+ | 158Dy | 5+  |
158m1Ho  | 67.20(1) keV  | 28(2) min  | IT (91%)  | 158Ho  | 2−  |
β+ (9%)  | 158Dy
158m2Ho  | 91.595(12) keV  | 140(25) ns  | IT  | 158Ho  | (2−)  |
158m3Ho  | 180(70)# keV  | 21.3(23) min  | β+ | 158Dy | (9+)  |
159Ho  | 67  | 92  | 158.9277187(33)  | 33.05(11) min  | β+ | 159Dy  | 7/2−  |
159mHo  | 205.91(5) keV  | 8.30(8) s  | IT  | 159Ho  | 1/2+  |
160Ho  | 67  | 93  | 159.928736(16)  | 25.6(3) min  | β+ | 160Dy | 5+  |
160m1Ho  | 59.98(3) keV  | 5.02(5) h  | IT (73%)  | 160Ho  | 2−  |
β+ (27%)  | 160Dy
160m2Ho  | 197(16) keV  | ~3 s  | IT  | 160Ho  | (9+)  |
161Ho  | 67  | 94  | 160.9278618(23)  | 2.48(5) h  | EC | 161Dy | 7/2−  |
161mHo  | 211.15(3) keV  | 6.76(7) s  | IT  | 161Ho  | 1/2+  |
162Ho  | 67  | 95  | 161.9291025(33)  | 15.0(10) min  | β+ | 162Dy | 1+  |
162mHo  | 105.87(6) keV  | 67.0(7) min  | IT (62%)  | 162Ho  | 6−  |
β+ (38%)  | 162Dy
163Ho  | 67  | 96  | 162.92874026(74)  | 4570(25) y  | EC  | 163Dy | 7/2−  |
163m1Ho  | 297.88(7) keV  | 1.09(3) s  | IT  | 163Ho  | 1/2+  |
163m2Ho  | 2109.4(4) keV  | 800(150) ns  | IT  | 163Ho  | (23/2+)  |
164Ho  | 67  | 97  | 163.9302405(15)  | 28.8(5) min  | EC (61%)  | 164Dy | 1+  |
β− (39%)  | 164Er
164mHo  | 139.78(7) keV  | 36.6(3) min  | IT  | 164Ho  | 6−  |
165Ho  | 67  | 98  | 164.93032912(84)  | Observationally Stable[n 9] | 7/2−  | 1.0000
165m1Ho  | 361.675(11) keV  | 1.512(4) μs  | IT  | 165Ho | 3/2+  |
165m2Ho  | 715.33(2) keV  | <100 ns  | IT  | 165Ho | 7/2+  |
166Ho  | 67  | 99  | 165.93229121(84)  | 26.812(7) h  | β− | 166Er | 0−  |
166m1Ho  | 5.969(12) keV  | 1132.6(39) y  | β− | 166Er | 7−  |
166m2Ho  | 190.9021(20) keV  | 185(15) μs  | IT  | 166Ho  | 3+  |
167Ho  | 67  | 100  | 166.9331403(56)  | 3.1(1) h  | β− | 167Er | 7/2−  |
167mHo  | 259.34(11) keV  | 6.0(10) μs  | IT  | 167Ho  | 3/2+  |
168Ho  | 67  | 101  | 167.935524(32)  | 2.99(7) min  | β− | 168Er | 3+  |
168m1Ho  | 59(1) keV  | 132(4) s  | IT  | 168Ho  | (6+)  |
168m2Ho  | 143.43(17) keV  | >4 μs  | IT  | 168Ho  | (1)−  |
168m3Ho  | 192.57(20) keV  | 108(11) ns  | IT  | 168Ho  | 1+  |
169Ho  | 67  | 102  | 168.936880(22)  | 4.72(10) min  | β− | 169Er  | 7/2−  |
169mHo  | 1386.2(4) keV  | 118(6) μs  | IT  | 169Ho  | (19/2+)  |
170Ho  | 67  | 103  | 169.939627(54)  | 2.76(5) min  | β− | 170Er | (6+)  |
170mHo[n 8] | 100(80) keV  | 43(2) s  | β− | 170Er | (1+)  |
171Ho  | 67  | 104  | 170.94147(64)  | 53(2) s  | β− | 171Er  | 7/2−#  |
172Ho  | 67  | 105  | 171.94473(21)#  | 25(3) s  | β− | 172Er  | 0+#  |
173Ho  | 67  | 106  | 172.94702(32)#  | 7.1(4) s  | β− | 173Er  | 7/2−#  |
173mHo  | 405(1) keV  | 3.7(12) μs  | IT  | 173Ho  | 1/2+#  |
174Ho  | 67  | 107  | 173.95076(32)#  | 3.7(4) s  | β− | 174Er  | (8−)  |
175Ho  | 67  | 108  | 174.95352(43)#  | 1.88(55) s  | β− | 175Er  | 7/2−#  |
176Ho  | 67  | 109  | 175.95771(54)#  | 1# s
[>300 ns]  |  |  | 4+#  |
177Ho  | 67  | 110  | 176.96105(54)#  | 1# s
[>550 ns]  | β− | 177Er  | 7/2−#  |
178Ho  | 67  | 111  | 177.96551(54)#  | 750# ms
[>550 ns]  |  |  | 2+#  |

1. ↑ mHo - 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. ↑ 4.0 4.1 4.2 # - Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
5. ↑ Modes of decay:  EC: | Electron capture

|

IT: | Isomeric transition
6. ↑ Bold symbol as daughter - Daughter product is stable.
7. ↑ ( ) spin value - Indicates spin with weak assignment arguments.
8. ↑ 8.0 8.1 Order of ground state and isomer is uncertain.
9. ↑ Believed to undergo α decay to 161Tb

## See also

Daughter products other than holmium

* Isotopes of erbium
* Isotopes of dysprosium
* Isotopes of terbium

## References

1. ↑ Suzuki, Yuka S (1998). "Biodistribution and kinetics of holmium-166-chitosan complex (DW-166HC) in rats and mice.". Journal of Nuclear Medicine 39 (12): 2161–2166. PMID 9867162. https://jnm.snmjournals.org/content/jnumed/39/12/2161.full.pdf.
2. ↑ Klaassen, Nienke J. M.; Arntz, Mark J.; Gil Arranja, Alexandra; Roosen, Joey; Nijsen, J. Frank W. (2019-08-05). "The various therapeutic applications of the medical isotope holmium-166: a narrative review". EJNMMI Radiopharmacy and Chemistry 4 (1): 19. doi:10.1186/s41181-019-0066-3. ISSN 2365-421X. PMID 31659560.
3. ↑ Suzuki, H; Fukuda, N; Takeda, H; Shimizu, Y; Yoshimoto, M; Togano, Y; Sato, H; Kitamura, N et al. (3 February 2026). "Discovery of Proton-Rich Radioactive Isotopes in the Z = 63–70 Region Produced by the Projectile Fragmentation of a 345-MeV/Nucleon 238U Beam". Progress of Theoretical and Experimental Physics 2026 (2). doi:10.1093/ptep/ptaf190.

* 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, doi:10.1016/j.nuclphysa.2003.11.001, Bibcode: 2003NuPhA.729....3A, https://hal.archives-ouvertes.fr/in2p3-00020241/document
* Isotopic compositions and standard atomic masses from:
* Template:CIAAW2003
* 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.
* 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, doi:10.1016/j.nuclphysa.2003.11.001, Bibcode: 2003NuPhA.729....3A, https://hal.archives-ouvertes.fr/in2p3-00020241/document
* National Nuclear Data Center. "NuDat 2.x database". Brookhaven National Laboratory. http://www.nndc.bnl.gov/nudat2/.
* Lide, David R., ed (2004). "11. Table of the Isotopes". CRC Handbook of Chemistry and Physics (85th ed.). Boca Raton, Florida: CRC Press. ISBN 978-0-8493-0485-9.

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