Isotopes of holmium

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.

Isotopes of holmium (₆₇Ho)

Main isotopes[1] Decay abun­dance half-life (t1/2) mode pro­duct 163Ho synth 4570 y ε 163Dy 164Ho synth 28.8 min ε 164Dy β− 164Er 165Ho 100% stable 166Ho synth 26.812 h β− 166Er 166m1Ho synth 1132.6 y β− 166Er 167Ho synth 3.1 h β− 167Er
Standard atomic weight Ar°(Ho)
	164.930329±0.000005[2] 164.93±0.01 (abridged)[3]
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Holmium-166m1 oxide

List of isotopes

Nuclide [n 1]	Z	N	Isotopic mass (Da) [n 2][n 3]	Half-life [n 4]	Decay mode [n 5]	Daughter isotope [n 6]	Spin and parity [n 7][n 4]	Isotopic abundance
	Excitation energy[n 4]
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−#
This table header & footer: view

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. # – 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

1. Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.
2. "Standard Atomic Weights: Holmium". CIAAW. 2021.
3. Prohaska, Thomas; Irrgeher, Johanna; Benefield, Jacqueline; Böhlke, John K.; Chesson, Lesley A.; Coplen, Tyler B.; Ding, Tiping; Dunn, Philip J. H.; Gröning, Manfred; Holden, Norman E.; Meijer, Harro A. J. (2022-05-04). "Standard atomic weights of the elements 2021 (IUPAC Technical Report)". Pure and Applied Chemistry. doi:10.1515/pac-2019-0603. ISSN 1365-3075.

• 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, Bibcode:2003NuPhA.729....3A, doi:10.1016/j.nuclphysa.2003.11.001
• Isotopic compositions and standard atomic masses from:
  • de Laeter, John Robert; Böhlke, John Karl; De Bièvre, Paul; Hidaka, Hiroshi; Peiser, H. Steffen; Rosman, Kevin J. R.; Taylor, Philip D. P. (2003). "Atomic weights of the elements. Review 2000 (IUPAC Technical Report)". Pure and Applied Chemistry. 75 (6): 683–800. doi:10.1351/pac200375060683.
  • 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.
• "News & Notices: Standard Atomic Weights Revised". International Union of Pure and Applied Chemistry. 19 October 2005.
• 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, Bibcode:2003NuPhA.729....3A, doi:10.1016/j.nuclphysa.2003.11.001
  • National Nuclear Data Center. "NuDat 2.x database". Brookhaven National Laboratory.
  • Holden, Norman E. (2004). "11. Table of the Isotopes". In Lide, David R. (ed.). CRC Handbook of Chemistry and Physics (85th ed.). Boca Raton, Florida: CRC Press. ISBN 978-0-8493-0485-9.