Isotopes of holmium

Natural holmium (Ho) contains one stable isotope, ¹⁶⁵Ho. A number of synthetic radioactive isotopes are known, 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 ^166mHo has a half-life of about 1,200 years), and most have half-lives under 3 hours.

Relative atomic mass: 164.93033(2).^[1]

Table

nuclide symbol	Z(p)	N(n)	isotopic mass (u)	half-life	decay mode(s)[2][n 1]	daughter isotope(s)[n 2]	nuclear spin	representative isotopic composition (mole fraction)	range of natural variation (mole fraction)
	excitation energy
^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 3]			7/2−	1.0000
^166Ho	67	99	165.9322842(27)	26.83(2) h	β^−	^166Er	0−
^166m1Ho	5.985(18) keV			1,200(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. Abbreviations:
   EC: Electron capture
   IT: Isomeric transition
2. Bold for stable isotopes
3. Believed to undergo α decay to ¹⁶¹Tb

Notes

• Values marked # are not purely derived from experimental data, but at least partly from systematic trends. Spins with weak assignment arguments are enclosed in parentheses.
• Uncertainties are given in concise form in parentheses after the corresponding last digits. Uncertainty values denote one standard deviation, except isotopic composition and standard atomic mass from IUPAC, which use expanded uncertainties.

References

1. Table of Standard Atomic Weights 2013 – CIAAW
2. "Universal Nuclide Chart". nucleonica. (registration required (help)).

• Isotope masses from:
  • G. Audi; A. H. Wapstra; C. Thibault; J. Blachot; O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties" (PDF). 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:
  • J. R. de Laeter; J. K. Böhlke; P. De Bièvre; H. Hidaka; H. S. Peiser; K. J. R. Rosman; P. D. P. Taylor (2003). "Atomic weights of the elements. Review 2000 (IUPAC Technical Report)". Pure and Applied Chemistry 75 (6): 683–800. doi:10.1351/pac200375060683.
  • M. E. Wieser (2006). "Atomic weights of the elements 2005 (IUPAC Technical Report)". Pure and Applied Chemistry 78 (11): 2051–2066. doi:10.1351/pac200678112051. Lay summary.
• Half-life, spin, and isomer data selected from the following sources. See editing notes on this article's talk page.
  • G. Audi; A. H. Wapstra; C. Thibault; J. Blachot; O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties" (PDF). Nuclear Physics A 729: 3–128. Bibcode:2003NuPhA.729....3A. doi:10.1016/j.nuclphysa.2003.11.001.
  • National Nuclear Data Center. "NuDat 2.1 database". Brookhaven National Laboratory. Retrieved September 2005.
  • N. E. Holden (2004). "Table of the Isotopes". In D. R. Lide. CRC Handbook of Chemistry and Physics (85th ed.). CRC Press. Section 11. ISBN 978-0-8493-0485-9.