Isotopes of holmium

Natural holmium (₆₇Ho) contains one observationally stable isotope, ¹⁶⁵Ho. The below table lists 39 isotopes spanning ¹⁴⁰Ho through ¹⁷⁸Ho as well as 40 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 27 hours in their ground states (although the metastable ^166m1Ho is 1,133 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 1133 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)[4] [n 2][n 3]	Half-life[1] [n 4]	Decay mode[1] [n 5]	Daughter isotope [n 6]	Spin and parity[1] [n 7][n 4]	Isotopic abundance
	Excitation energy[n 4]
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	67	76	142.95486(32)#	300# ms [>200 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+#
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. 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