Isotopes of holmium

Short description: List of isotopes having 67 protons in their nuclei

Natural holmium (67Ho) contains one observationally stable isotope, 165Ho. The below table lists 36 isotopes spanning 140Ho through 175Ho as well as 33 nuclear isomers. Among the known synthetic radioactive isotopes; the most stable one is 163Ho, 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 166m1Ho has a half-life of about 1,200 years), and most have half-lives under 3 hours.

Theoretically, the only "stable" isotope of holmium, 165Ho, as well as all nuclides in the beta-decay stable isobars with mass number ≥165, can go alpha decay, hence 164Dy is the heaviest theoretically stable nuclide.

## List of isotopes

Holmium-166m1 oxide 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  | 139.96854(54)#  | 6(3) ms  |  |  | 8+#  |  |
141Ho  | 67  | 74  | 140.96310(54)#  | 4.1(3) ms  |  |  | (7/2−)  |  |
141mHo  | 66(2) keV  | 6.4(8) µs  |  |  | (1/2+)  |  |
142Ho  | 67  | 75  | 141.95977(54)#  | 400(100) ms  | β+ | 142Dy  | (6 to 9)  |  |
p | 141Dy
143Ho  | 67  | 76  | 142.95461(43)#  | 300# ms
[>200 ns]  | β+ | 143Dy  | 11/2−#  |  |
144Ho  | 67  | 77  | 143.95148(32)#  | 0.7(1) s  | β+ | 144Dy  |  |  |
β+, p  | 143Tb
145Ho  | 67  | 78  | 144.94720(32)#  | 2.4(1) s  | β+ | 145Dy  | (11/2−)  |  |
145mHo  | 100(100)# keV  | 100# ms  |  |  | 5/2+#  |  |
146Ho  | 67  | 79  | 145.94464(21)#  | 3.6(3) s  | β+ | 146Dy  | (10+)  |  |
β+, p (rare)  | 145Tb
147Ho  | 67  | 80  | 146.94006(3)  | 5.8(4) s  | β+ | 147Dy  | (11/2−)  |  |
β+, p (rare)  | 146Tb
148Ho  | 67  | 81  | 147.93772(14)  | 2.2(11) s  | β+ | 148Dy  | (1+)  |  |
148m1Ho  | 400(100)# keV  | 9.49(12) s  | β+ (99.92%)  | 148Dy  | (6)−  |  |
β+, p (.08%)  | 147Tb
148m2Ho  | 690(100)# keV  | 2.35(4) ms  |  |  | (10+)  |  |
149Ho  | 67  | 82  | 148.933775(20)  | 21.1(2) s  | β+ | 149Dy  | (11/2−)  |  |
149m1Ho  | 48.80(20) keV  | 56(3) s  | β+ | 149Dy  | (1/2+)  |  |
149m2Ho  | 7200(350) keV  | >=100 ns  |  |  |  |  |
150Ho  | 67  | 83  | 149.933496(15)  | 76.8(18) s  | β+ | 150Dy  | 2−  |  |
150m1Ho  | −10(50) keV  | 23.3(3) s  | β+ | 150Dy  | (9)+  |  |
150m2Ho  | ~8000 keV  | 751 ns  |  |  |  |  |
151Ho  | 67  | 84  | 150.931688(13)  | 35.2(1) s  | β+ (78%)  | 151Dy  | 11/2(−)  |  |
α (22%)  | 147Tb
151mHo  | 41.0(2) keV  | 47.2(10) s  | α (77%)  | 147Tb  | 1/2(+)  |  |
β+ (22%)  | 151Dy
152Ho  | 67  | 85  | 151.931714(15)  | 161.8(3) s  | β+ (88%)  | 152Dy  | 2−  |  |
α (12%)  | 148Tb
152m1Ho  | 160(1) keV  | 50.0(4) s  |  |  | 9+  |  |
152m2Ho  | 3019.59(19) keV  | 8.4(3) µs  |  |  | 19−  |  |
153Ho  | 67  | 86  | 152.930199(6)  | 2.01(3) min  | β+ (99.94%)  | 153Dy  | 11/2−  |  |
α (.05%)  | 149Tb
153m1Ho  | 68.7(3) keV  | 9.3(5) min  | β+ (99.82%)  | 153Dy  | 1/2+  |  |
α (.18%)  | 149Tb
153m2Ho  | 2772 keV  | 229(2) ns  |  |  | (31/2+)  |  |
154Ho  | 67  | 87  | 153.930602(9)  | 11.76(19) min  | β+ (99.98%)  | 154Dy  | 2−  |  |
α (.02%)  | 150Tb
154mHo  | 238(30) keV  | 3.10(14) min  | β+ (99.99%)  | 154Dy  | 8+  |  |
α (.001%)  | 150Tb
IT (rare)  | 154Ho
155Ho  | 67  | 88  | 154.929103(19)  | 48(1) min  | β+ | 155Dy  | 5/2+  |  |
155mHo  | 141.97(11) keV  | 880(80) µs  |  |  | 11/2−  |  |
156Ho  | 67  | 89  | 155.92984(5)  | 56(1) min  | β+ | 156Dy | 4−  |  |
156m1Ho  | 100(50)# keV  | 7.8(3) min  | β+ | 156Dy | (9+)  |  |
IT  | 156Ho
156m2Ho  | 52.4(5) keV  | 9.5(15) s  |  |  | 1−  |  |
157Ho  | 67  | 90  | 156.928256(26)  | 12.6(2) min  | β+ | 157Dy  | 7/2−  |  |
158Ho  | 67  | 91  | 157.928941(29)  | 11.3(4) min  | β+ (93%)  | 158Dy | 5+  |  |
α (7%)  | 154Tb
158m1Ho  | 67.200(10) keV  | 28(2) min  | IT (81%)  | 158Ho  | 2−  |  |
β+ (19%)  | 158Dy
158m2Ho  | 180(70)# keV  | 21.3(23) min  |  |  | (9+)  |  |
159Ho  | 67  | 92  | 158.927712(4)  | 33.05(11) min  | β+ | 159Dy  | 7/2−  |  |
159mHo  | 205.91(5) keV  | 8.30(8) s  | IT  | 159Ho  | 1/2+  |  |
160Ho  | 67  | 93  | 159.928729(16)  | 25.6(3) min  | β+ | 160Dy | 5+  |  |
160m1Ho  | 59.98(3) keV  | 5.02(5) h  | IT (65%)  | 160Ho  | 2−  |  |
β+ (35%)  | 160Dy
160m2Ho  | 197(16) keV  | 3 s  |  |  | (9+)  |  |
161Ho  | 67  | 94  | 160.927855(3)  | 2.48(5) h  | EC | 161Dy | 7/2−  |  |
161mHo  | 211.16(3) keV  | 6.76(7) s  | IT  | 161Ho  | 1/2+  |  |
162Ho  | 67  | 95  | 161.929096(4)  | 15.0(10) min  | β+ | 162Dy | 1+  |  |
162mHo  | 106(7) keV  | 67.0(7) min  | IT (62%)  | 162Ho  | 6−  |  |
β+ (38%)  | 162Dy
163Ho  | 67  | 96  | 162.9287339(27)  | 4570(25) y  | EC  | 163Dy | 7/2−  |  |
163mHo  | 297.88(7) keV  | 1.09(3) s  | IT  | 163Ho  | 1/2+  |  |
164Ho  | 67  | 97  | 163.9302335(30)  | 29(1) min  | EC (60%)  | 164Dy | 1+  |  |
β− (40%)  | 164Er
164mHo  | 139.77(8) keV  | 38.0(10) min
[37.5(+15−5) min]  | IT  | 164Ho  | 6−  |  |
165Ho  | 67  | 98  | 164.9303221(27)  | Observationally Stable[n 8] | 7/2−  | 1.0000  |
166Ho  | 67  | 99  | 165.9322842(27)  | 26.83(2) h  | β− | 166Er | 0−  |  |
166m1Ho  | 5.985(18) keV  | 1200(180) y  | β− | 166Er | (7)−  |  |
166m2Ho  | 190.9052(20) keV  | 185(15) µs  |  |  | 3+  |  |
167Ho  | 67  | 100  | 166.933133(6)  | 3.003(18) h  | β− | 167Er | 7/2−  |  |
167mHo  | 259.34(11) keV  | 6.0(10) µs  |  |  | 3/2+  |  |
168Ho  | 67  | 101  | 167.93552(3)  | 2.99(7) min  | β− | 168Er | 3+  |  |
168m1Ho  | 59(1) keV  | 132(4) s  | IT (99.5%)  | 168Ho  | (6+)  |  |
β− (.5%)  | 168Er
168m2Ho  | 143.4(2) keV  | >4 µs  |  |  | (1)−  |  |
168m3Ho  | 192.6(2) keV  | 108(11) ns  |  |  | 1+  |  |
169Ho  | 67  | 102  | 168.936872(22)  | 4.72(10) min  | β− | 169Er  | 7/2−  |  |
170Ho  | 67  | 103  | 169.93962(5)  | 2.76(5) min  | β− | 170Er | 6+#  |  |
170mHo  | 120(70) keV  | 43(2) s  | β− | 170Er | (1+)  |  |
171Ho  | 67  | 104  | 170.94147(64)  | 53(2) s  | β− | 171Er  | 7/2−#  |  |
172Ho  | 67  | 105  | 171.94482(43)#  | 25(3) s  | β− | 172Er  |  |  |
173Ho  | 67  | 106  | 172.94729(43)#  | 10# s  | β− | 173Er  | 7/2−#  |  |
174Ho  | 67  | 107  | 173.95115(54)#  | 8# s  |  |  |  |  |
175Ho  | 67  | 108  | 174.95405(64)#  | 5# s  |  |  | 7/2−#  |  |

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. ↑ Believed to undergo α decay to 161Tb

## References

* 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:
* 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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