Isotopes of holmium

Isotopes of holmium (₆₇Ho)
β−	164Er
Standard atomic weight Ar°(Ho)
	164.930329±0.000005; 164.93±0.01 (abridged);

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.^[4]^[5]

List of isotopes

Nuclide ^{[n 1]}	Z	N	Isotopic mass (Da)^[6] ^{[n 2]}^{[n 3]}	Discovery year^[7]^[8]	Half-life^[1] ^{[n 4]}	Decay mode^[1] ^{[n 5]}	Daughter isotope ^{[n 6]}	Spin and parity^[1] ^{[n 7]}^{[n 4]}	Isotopic abundance
Nuclide ^{[n 1]}	Excitation energy^{[n 4]}			Discovery year^[7]^[8]	Half-life^[1] ^{[n 4]}	Decay mode^[1] ^{[n 5]}	Daughter isotope ^{[n 6]}	Spin and parity^[1] ^{[n 7]}^{[n 4]}	Isotopic abundance
¹⁴⁰Ho	67	73	139.96853(54)#	1999	6(3) ms	p	¹³⁹Dy	8+#
¹⁴¹Ho	67	74	140.96311(43)#	1998	4.1(1) ms	p	¹⁴⁰Dy	(7/2−)
^141mHo	66(2) keV			1998	7.3(3) μs	p	¹⁴⁰Dy	(1/2+)
¹⁴²Ho	67	75	141.96001(43)#	2001	400(100) ms	β⁺	¹⁴²Dy	(7−, 8+)
						β⁺, p (?%)	¹⁴¹Tb
						p (?%)	¹⁴¹Dy
¹⁴³Ho^[9]	67	76	142.95486(32)#	2026	300# ms [>310 ns]			11/2−#
¹⁴⁴Ho	67	77	143.9521097(91)	1986	0.7(1) s	β⁺	¹⁴⁴Dy	(5−)
¹⁴⁴Ho	67	77	143.9521097(91)	1986	0.7(1) s	β⁺, p (?%)	¹⁴³Tb	(5−)
^144mHo	265.3(3) keV			2001	519(5) ns	IT	¹⁴⁴Ho	(8+)
¹⁴⁵Ho	67	78	144.9472674(80)	1987	2.4(1) s	β⁺	¹⁴⁵Dy	(11/2−)
¹⁴⁶Ho	67	79	145.9449935(71)	1982	3.32(22) s	β⁺	¹⁴⁶Dy	(6−)
¹⁴⁶Ho	67	79	145.9449935(71)	1982	3.32(22) s	β⁺, p (?%)	¹⁴⁵Tb	(6−)
¹⁴⁷Ho	67	80	146.9401423(54)	1982	5.8(4) s	β⁺	¹⁴⁷Dy	(11/2−)
^147mHo	2687.1(4) keV			1982	315(30) ns	IT	¹⁴⁷Ho	(27/2−)
¹⁴⁸Ho	67	81	147.937744(90)	1979	2.2(11) s	β⁺	¹⁴⁸Dy	(1+)
^148m1Ho	250(100)# keV			1982	9.49(12) s	β⁺ (99.92%)	¹⁴⁸Dy	(5−)
^148m1Ho	250(100)# keV			1982	9.49(12) s	β⁺, p (0.08%)	¹⁴⁷Tb	(5−)
^148m2Ho	940(100)# keV			1984	2.36(6) ms	IT	^148m1Ho	(10)+
¹⁴⁹Ho	67	82	148.933820(13)	1979	21.1(2) s	β⁺	¹⁴⁹Dy	(11/2−)
^149mHo	48.80(20) keV			1989	56(3) s	β⁺	¹⁴⁹Dy	(1/2+)
¹⁵⁰Ho	67	83	149.933498(15)	1963	76.8(18) s	β⁺	¹⁵⁰Dy	(2)−
^150m1Ho^{[n 8]}	0(50) keV			1980	23.3(3) s	β⁺	¹⁵⁰Dy	(9)+
^150m2Ho	7900(50) keV			1981	787(36) ns	IT	¹⁵⁰Ho	(28−)
¹⁵¹Ho	67	84	150.9316982(89)	1963	35.2(1) s	β⁺ (78%)	¹⁵¹Dy	11/2−
¹⁵¹Ho	67	84	150.9316982(89)	1963	35.2(1) s	α (22%)	¹⁴⁷Tb	11/2−
^151mHo	41.0(2) keV			1963	47.2(13) s	α (77%)	¹⁴⁷Tb	1/2+
^151mHo	41.0(2) keV			1963	47.2(13) s	β⁺ (23%)	¹⁵¹Dy	1/2+
¹⁵²Ho	67	85	151.931718(13)	1963	161.8(3) s	β⁺ (88%)	¹⁵²Dy	2−
¹⁵²Ho	67	85	151.931718(13)	1963	161.8(3) s	α (12%)	¹⁴⁸Tb	2−
^152m1Ho	160(3) keV			1963	49.8(2) s	β⁺ (89.2%)	¹⁵²Dy	9+
^152m1Ho	160(3) keV			1963	49.8(2) s	α (10.8%)	¹⁴⁸Tb	9+
^152m2Ho	3019.59(19) keV			1994	8.4(3) μs	IT	¹⁵²Ho	19−
¹⁵³Ho	67	86	152.9302067(54)	1963	2.01(3) min	β⁺ (99.95%)	¹⁵³Dy	11/2−
¹⁵³Ho	67	86	152.9302067(54)	1963	2.01(3) min	α (0.051%)	¹⁴⁹Tb	11/2−
^153m1Ho	68.7(3) keV			1971	9.3(5) min	β⁺ (99.82%)	¹⁵³Dy	1/2+
^153m1Ho	68.7(3) keV			1971	9.3(5) min	α (0.18%)	¹⁴⁹Tb	1/2+
^153m2Ho	2772.3(14) keV			1980	229(2) ns	IT	¹⁵³Ho	31/2+
¹⁵⁴Ho	67	87	153.9306068(88)	1966	11.76(19) min	β⁺ (99.98%)	¹⁵⁴Dy	2−
¹⁵⁴Ho	67	87	153.9306068(88)	1966	11.76(19) min	α (0.019%)	¹⁵⁰Tb	2−
^154mHo	243(28) keV			1968	3.10(14) min	β⁺	¹⁵⁴Dy	8+
						α (<0.001%)	¹⁵⁰Tb
						IT (rare)	¹⁵⁴Ho
¹⁵⁵Ho	67	88	154.929103(19)	1959	48(2) min	β⁺	¹⁵⁵Dy	5/2+
^155mHo	141.87(11) keV			1979	880(80) μs	IT	¹⁵⁵Ho	11/2−
¹⁵⁶Ho	67	89	155.929642(41)	1957	56(1) min	β⁺	¹⁵⁶Dy	4−
^156m1Ho	52.37(30) keV			(1995)^{[n 9]}	9.5(15) s	IT	¹⁵⁶Ho	1−
^156m2Ho	230(50) keV			(1999)^{[n 9]}	7.6(3) min	β⁺ (75%)	¹⁵⁶Dy	9+
^156m2Ho	230(50) keV			(1999)^{[n 9]}	7.6(3) min	IT (25%)	¹⁵⁶Ho	9+
¹⁵⁷Ho	67	90	156.928252(25)	1965	12.6(2) min	β⁺	¹⁵⁷Dy	7/2−
¹⁵⁸Ho	67	91	157.928945(29)	1960	11.3(4) min	β⁺	¹⁵⁸Dy	5+
^158m1Ho	67.20(1) keV			1962	28(2) min	IT (91%)	¹⁵⁸Ho	2−
^158m1Ho	67.20(1) keV			1962	28(2) min	β⁺ (9%)	¹⁵⁸Dy	2−
^158m2Ho	91.595(12) keV			(2005)^{[n 9]}	140(25) ns	IT	¹⁵⁸Ho	(2−)
^158m3Ho	180(70)# keV			1974	21.3(23) min	β⁺	¹⁵⁸Dy	(9+)
¹⁵⁹Ho	67	92	158.9277187(33)	1958	33.05(11) min	β⁺	¹⁵⁹Dy	7/2−
^159mHo	205.91(5) keV			1965	8.30(8) s	IT	¹⁵⁹Ho	1/2+
¹⁶⁰Ho	67	93	159.928736(16)	1950	25.6(3) min	β⁺	¹⁶⁰Dy	5+
^160m1Ho	59.98(3) keV			1955	5.02(5) h	IT (73%)	¹⁶⁰Ho	2−
^160m1Ho	59.98(3) keV			1955	5.02(5) h	β⁺ (27%)	¹⁶⁰Dy	2−
^160m2Ho	197(16) keV			1988	~3 s	IT	¹⁶⁰Ho	(9+)
¹⁶¹Ho	67	94	160.9278618(23)	1954	2.48(5) h	EC	¹⁶¹Dy	7/2−
^161mHo	211.15(3) keV			1965	6.76(7) s	IT	¹⁶¹Ho	1/2+
¹⁶²Ho	67	95	161.9291025(33)	1957	15.0(10) min	β⁺	¹⁶²Dy	1+
^162mHo	105.87(6) keV			1961	67.0(7) min	IT (62%)	¹⁶²Ho	6−
^162mHo	105.87(6) keV			1961	67.0(7) min	β⁺ (38%)	¹⁶²Dy	6−
¹⁶³Ho	67	96	162.92874026(74)	1957	4570(25) y	EC	¹⁶³Dy	7/2−
^163m1Ho	297.88(7) keV			1957	1.09(3) s	IT	¹⁶³Ho	1/2+
^163m2Ho	2109.4(4) keV			2012	800(150) ns	IT	¹⁶³Ho	(23/2+)
¹⁶⁴Ho	67	97	163.9302405(15)	1938	28.8(5) min	EC (61%)	¹⁶⁴Dy	1+
¹⁶⁴Ho	67	97	163.9302405(15)	1938	28.8(5) min	β⁻ (39%)	¹⁶⁴Er	1+
^164mHo	139.78(7) keV			1966	36.6(3) min	IT	¹⁶⁴Ho	6−
¹⁶⁵Ho	67	98	164.93032912(84)	1934	Observationally Stable^{[n 10]}			7/2−	1.0000
^165m1Ho	361.675(11) keV			1959	1.512(4) μs	IT	¹⁶⁵Ho	3/2+
^165m2Ho	715.33(2) keV			(1958)^{[n 11]}	<100 ns	IT	¹⁶⁵Ho	7/2+
¹⁶⁶Ho	67	99	165.93229121(84)	1936	26.812(7) h	β⁻	¹⁶⁶Er	0−
^166m1Ho	5.969(12) keV			1952	1132.6(39) y	β⁻	¹⁶⁶Er	7−
^166m2Ho	190.9021(20) keV			1960	185(15) μs	IT	¹⁶⁶Ho	3+
¹⁶⁷Ho	67	100	166.9331403(56)	1955	3.1(1) h	β⁻	¹⁶⁷Er	7/2−
^167mHo	259.34(11) keV			1977	6.0(10) μs	IT	¹⁶⁷Ho	3/2+
¹⁶⁸Ho	67	101	167.935524(32)	1960	2.99(7) min	β⁻	¹⁶⁸Er	3+
^168m1Ho	59(1) keV			1990	132(4) s	IT	¹⁶⁸Ho	(6+)
^168m2Ho	143.43(17) keV			1990	>4 μs	IT	¹⁶⁸Ho	(1)−
^168m3Ho	192.57(20) keV			1990	108(11) ns	IT	¹⁶⁸Ho	1+
¹⁶⁹Ho	67	102	168.936880(22)	1963	4.72(10) min	β⁻	¹⁶⁹Er	7/2−
^169mHo	1386.2(4) keV			2010	118(6) μs	IT	¹⁶⁹Ho	(19/2+)
¹⁷⁰Ho	67	103	169.939627(54)	1960	2.76(5) min	β⁻	¹⁷⁰Er	(6+)
^170mHo^{[n 8]}	100(80) keV			1969	43(2) s	β⁻	¹⁷⁰Er	(1+)
¹⁷¹Ho	67	104	170.94147(64)	1989	53(2) s	β⁻	¹⁷¹Er	7/2−#
¹⁷²Ho	67	105	171.94473(21)#	1991	25(3) s	β⁻	¹⁷²Er	0+#
¹⁷³Ho	67	106	172.94702(32)#	2012	7.1(4) s	β⁻	¹⁷³Er	7/2−#
^173mHo	405(1) keV			2020	3.7(12) μs	IT	¹⁷³Ho	1/2+#
¹⁷⁴Ho	67	107	173.95076(32)#	2012	3.7(4) s	β⁻	¹⁷⁴Er	(8−)
¹⁷⁵Ho	67	108	174.95352(43)#	2012	1.88(55) s	β⁻	¹⁷⁵Er	7/2−#
¹⁷⁶Ho	67	109	175.95771(54)#	2012	1# s [>300 ns]			4+#
¹⁷⁷Ho	67	110	176.96105(54)#	2018	1# s [>550 ns]	β⁻	¹⁷⁷Er	7/2−#
¹⁷⁸Ho	67	111	177.96551(54)#	2018	750# ms [>550 ns]			2+#
This table header & footer:

^ ^mHo – 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).
^ ^a ^b ^c # – 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.
^ ^a ^b Order of ground state and isomer is uncertain.
^ ^a ^b ^c Only published in a conference proceeding and not a refereed journal.
^ Believed to undergo α decay to ¹⁶¹Tb
^ Half-life less than 100 ns, not included in the discovery database.

References

^ ^a ^b ^c ^d 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.
^ "Standard Atomic Weights: Holmium". CIAAW. 2021.
^ 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.
^ Suzuki, Yuka S (1998). "Biodistribution and kinetics of holmium-166-chitosan complex (DW-166HC) in rats and mice" (PDF). Journal of Nuclear Medicine. 39 (12): 2161–2166. PMID 9867162.
^ 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. PMC 6682843. PMID 31659560.
^ Wang, Meng; Huang, W.J.; Kondev, F.G.; Audi, G.; Naimi, S. (2021). "The AME 2020 atomic mass evaluation (II). Tables, graphs and references*". Chinese Physics C. 45 (3) 030003. doi:10.1088/1674-1137/abddaf.
^ FRIB Nuclear Data Group. "Discovery of Nuclides Project, Isotope Database". doi:10.11578/frib/2279152.
^ FRIB Nuclear Data Group. "Discovery of Nuclides Project, Isomer Database". doi:10.11578/frib/2572219.
^ Suzuki, H; Fukuda, N; Takeda, H; Shimizu, Y; Yoshimoto, M; Togano, Y; Sato, H; Kitamura, N; Momota, S; Kusaka, K; Yanagisawa, Y; Ohtake, M; Fukunishi, N; Michimasa, S (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, 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 3.0 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.

[6] Ho – Excited nuclear isomer.

[8] ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.

[TMS-9] # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).

[TNN-12] # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).

[13] Modes of decay:

EC: Electron capture

IT: Isomeric transition

[14] Bold symbol as daughter – Daughter product is stable.

[15] ( ) spin value – Indicates spin with weak assignment arguments.

[order-17] Order of ground state and isomer is uncertain.

[conf-18] Only published in a conference proceeding and not a refereed journal.

[19] Believed to undergo α decay to ¹⁶¹Tb

[20] Half-life less than 100 ns, not included in the discovery database.

[NUBASE2020-1] 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.

[CIAAWholmium-2] "Standard Atomic Weights: Holmium". CIAAW. 2021.

[CIAAW2021-3] 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.

[4] Suzuki, Yuka S (1998). "Biodistribution and kinetics of holmium-166-chitosan complex (DW-166HC) in rats and mice" (PDF). Journal of Nuclear Medicine. 39 (12): 2161–2166. PMID 9867162.

[5] 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. PMC 6682843. PMID 31659560.

[AME2020_II-7] Wang, Meng; Huang, W.J.; Kondev, F.G.; Audi, G.; Naimi, S. (2021). "The AME 2020 atomic mass evaluation (II). Tables, graphs and references*". Chinese Physics C. 45 (3) 030003. doi:10.1088/1674-1137/abddaf.

[IsotopeFRIB-10] FRIB Nuclear Data Group. "Discovery of Nuclides Project, Isotope Database". doi:10.11578/frib/2279152.

[IsomerFRIB-11] FRIB Nuclear Data Group. "Discovery of Nuclides Project, Isomer Database". doi:10.11578/frib/2572219.

[suzuki2026-16] Suzuki, H; Fukuda, N; Takeda, H; Shimizu, Y; Yoshimoto, M; Togano, Y; Sato, H; Kitamura, N; Momota, S; Kusaka, K; Yanagisawa, Y; Ohtake, M; Fukunishi, N; Michimasa, S (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.

[1]

[2]

[3]

[4]

[5]

[n 1]

[6]

[n 2]

[n 3]

[7]

[8]

[n 4]

[n 5]

[n 6]

[n 7]

[9]

[n 8]

[n 9]

[n 10]

[n 11]

EC:	Electron capture
IT:	Isomeric transition

List of isotopes

See also

References