Isotopes of promethium

Isotopes of promethium (₆₁Pm)
αあるふぁ	141Pr
βべーた−	146Sm
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Promethium (₆₁Pm) is an artificial element, except in trace quantities as a product of spontaneous fission of ²³⁸U and ²³⁵U and alpha decay of ¹⁵¹Eu, and thus a standard atomic weight cannot be given. Like all artificial elements, it has no stable isotopes. It was first synthesized in 1945.

Forty-one radioisotopes have been characterized, with the most stable being ¹⁴⁵Pm with a half-life of 17.7 years, ¹⁴⁶Pm with a half-life of 5.53 years, and ¹⁴⁷Pm with a half-life of 2.6234 years. All of the remaining radioactive isotopes have half-lives that are less than 365 days, and the majority of these have half-lives that are less than 30 seconds. This element also has 18 meta states with the most stable being ^148mPm (t_1/2 41.29 days), ^152m2Pm (t_1/2 13.8 minutes) and ^152mPm (t_1/2 7.52 minutes).

The isotopes of promethium range in mass number from 126 to 166. The primary decay mode for ¹⁴⁶Pm and lighter isotopes is electron capture, and the primary mode for heavier isotopes is beta decay. The primary decay products before ¹⁴⁶Pm are isotopes of neodymium, and the primary products after are isotopes of samarium.

List of isotopes[edit]

Nuclide ^{[n 1]}	Z	N	Isotopic mass (Da) ^{[n 2]}^{[n 3]}	Half-life ^{[n 4]}	Decay mode ^{[n 5]}	Daughter isotope ^{[n 6]}^{[n 7]}	Spin and parity ^{[n 8]}^{[n 4]}	Isotopic abundance
Nuclide ^{[n 1]}	Excitation energy^{[n 4]}			Half-life ^{[n 4]}	Decay mode ^{[n 5]}	Daughter isotope ^{[n 6]}^{[n 7]}	Spin and parity ^{[n 8]}^{[n 4]}	Isotopic abundance
¹²⁶Pm	61	65	125.95752(54)#	0.5# s
¹²⁷Pm	61	66	126.95163(64)#	1# s			5/2+#
¹²⁸Pm	61	67	127.94842(43)#	1.0(3) s	βべーた⁺	¹²⁸Nd	6+#
¹²⁸Pm	61	67	127.94842(43)#	1.0(3) s	p	¹²⁷Nd	6+#
¹²⁹Pm	61	68	128.94316(43)#	3# s [>200 ns]	βべーた⁺	¹²⁹Nd	5/2+#
¹³⁰Pm	61	69	129.94045(32)#	2.6(2) s	βべーた⁺	¹³⁰Nd	(5+, 6+, 4+)
¹³⁰Pm	61	69	129.94045(32)#	2.6(2) s	βべーた⁺, p (rare)	¹²⁹Pr	(5+, 6+, 4+)
¹³¹Pm	61	70	130.93587(21)#	6.3(8) s	βべーた⁺, p	¹³⁰Pr	5/2+#
¹³¹Pm	61	70	130.93587(21)#	6.3(8) s	βべーた⁺	¹³¹Nd	5/2+#
¹³²Pm	61	71	131.93375(21)#	6.2(6) s	βべーた⁺	¹³²Nd	(3+)
¹³²Pm	61	71	131.93375(21)#	6.2(6) s	βべーた⁺, p (5×10⁻⁵%)	¹³¹Pr	(3+)
¹³³Pm	61	72	132.92978(5)	15(3) s	βべーた⁺	¹³³Nd	(3/2+)
^133mPm	130.4(10) keV			10# s	βべーた⁺	¹³³Nd	(11/2−)
^133mPm	130.4(10) keV			10# s	IT	¹³³Pm	(11/2−)
¹³⁴Pm	61	73	133.92835(6)	22(1) s	βべーた⁺	¹³⁴Nd	(5+)
^134mPm	0(100)# keV			~5 s	IT	¹³⁴Pm	(2+)
¹³⁵Pm	61	74	134.92488(6)	49(3) s	βべーた⁺	¹³⁵Nd	(5/2+, 3/2+)
^135mPm	50(100)# keV			40(3) s	βべーた⁺	¹³⁵Nd	(11/2−)
¹³⁶Pm	61	75	135.92357(8)	107(6) s	βべーた⁺	¹³⁶Nd	(5−)
^136mPm	130(120) keV			47(2) s	βべーた⁺	¹³⁶Nd	(2+)
¹³⁷Pm	61	76	136.920479(14)	2# min	βべーた⁺	¹³⁷Nd	5/2+#
^137mPm	150(50) keV			2.4(1) min	βべーた⁺	¹³⁷Nd	11/2−
¹³⁸Pm	61	77	137.919548(30)	10(2) s	βべーた⁺	¹³⁸Nd	1+#
^138mPm	30(30) keV			3.24(5) min	βべーた⁺	¹³⁸Nd	5−#
¹³⁹Pm	61	78	138.916804(14)	4.15(5) min	βべーた⁺	¹³⁹Nd	(5/2)+
^139mPm	188.7(3) keV			180(20) ms	IT (99.83%)	¹³⁹Pm	(11/2)−
^139mPm	188.7(3) keV			180(20) ms	βべーた⁺ (0.17%)	¹³⁹Nd	(11/2)−
¹⁴⁰Pm	61	79	139.91604(4)	9.2(2) s	βべーた⁺	¹⁴⁰Nd	1+
^140mPm	420(40) keV			5.95(5) min	βべーた⁺	¹⁴⁰Nd	8−
¹⁴¹Pm	61	80	140.913555(15)	20.90(5) min	βべーた⁺	¹⁴¹Nd	5/2+
^141m1Pm	628.40(10) keV			630(20) ns			11/2−
^141m2Pm	2530.9(5) keV			>2 μみゅーs
¹⁴²Pm	61	81	141.912874(27)	40.5(5) s	βべーた⁺	¹⁴²Nd	1+
^142mPm	883.17(16) keV			2.0(2) ms	IT	¹⁴²Pm	(8)−
¹⁴³Pm	61	82	142.910933(4)	265(7) d	EC	¹⁴³Nd	5/2+
¹⁴³Pm	61	82	142.910933(4)	265(7) d	βべーた⁺ (<5.7×10⁻⁶%)^[1]	¹⁴³Nd	5/2+
¹⁴⁴Pm	61	83	143.912591(3)	363(14) d	EC	¹⁴⁴Nd	5−
¹⁴⁴Pm	61	83	143.912591(3)	363(14) d	βべーた⁺ (<8×10⁻⁵%)^[1]	¹⁴⁴Nd	5−
^144m1Pm	840.90(5) keV			780(200) ns			(9)+
^144m2Pm	8595.8(22) keV			~2.7 μみゅーs			(27+)
¹⁴⁵Pm	61	84	144.912749(3)	17.7(4) y	EC	¹⁴⁵Nd	5/2+
¹⁴⁵Pm	61	84	144.912749(3)	17.7(4) y	αあるふぁ (2.8×10⁻⁷%)	¹⁴¹Pr	5/2+
¹⁴⁶Pm	61	85	145.914696(5)	5.53(5) y	EC (66%)	¹⁴⁶Nd	3−
¹⁴⁶Pm	61	85	145.914696(5)	5.53(5) y	βべーた⁻ (34%)	¹⁴⁶Sm	3−
¹⁴⁷Pm^{[n 9]}	61	86	146.9151385(26)	2.6234(2) y	βべーた⁻	¹⁴⁷Sm	7/2+	Trace^{[n 10]}
¹⁴⁸Pm	61	87	147.917475(7)	5.368(2) d	βべーた⁻	¹⁴⁸Sm	1−
^148mPm	137.9(3) keV			41.29(11) d	βべーた⁻ (95%)	¹⁴⁸Sm	5−, 6−
^148mPm	137.9(3) keV			41.29(11) d	IT (5%)	¹⁴⁸Pm	5−, 6−
¹⁴⁹Pm^{[n 9]}	61	88	148.918334(4)	53.08(5) h	βべーた⁻	¹⁴⁹Sm	7/2+
^149mPm	240.214(7) keV			35(3) μみゅーs			11/2−
¹⁵⁰Pm	61	89	149.920984(22)	2.68(2) h	βべーた⁻	¹⁵⁰Sm	(1−)
¹⁵¹Pm^{[n 9]}	61	90	150.921207(6)	28.40(4) h	βべーた⁻	¹⁵¹Sm	5/2+
¹⁵²Pm	61	91	151.923497(28)	4.12(8) min	βべーた⁻	¹⁵²Sm	1+
^152m1Pm	140(90) keV			7.52(8) min			4−
^152m2Pm	250(150)# keV			13.8(2) min			(8)
¹⁵³Pm	61	92	152.924117(12)	5.25(2) min	βべーた⁻	¹⁵³Sm	5/2−
¹⁵⁴Pm	61	93	153.92646(5)	1.73(10) min	βべーた⁻	¹⁵⁴Sm	(0, 1)
^154mPm	120(120) keV			2.68(7) min	βべーた⁻	¹⁵⁴Sm	(3, 4)
¹⁵⁵Pm	61	94	154.92810(3)	41.5(2) s	βべーた⁻	¹⁵⁵Sm	(5/2−)
¹⁵⁶Pm	61	95	155.93106(4)	26.70(10) s	βべーた⁻	¹⁵⁶Sm	4−
¹⁵⁷Pm	61	96	156.93304(12)	10.56(10) s	βべーた⁻	¹⁵⁷Sm	(5/2−)
¹⁵⁸Pm	61	97	157.93656(14)	4.8(5) s	βべーた⁻	¹⁵⁸Sm
¹⁵⁹Pm	61	98	158.93897(21)#	1.648+0.43 −0.42 s^[2]	βべーた⁻	¹⁵⁹Sm	5/2−#
¹⁶⁰Pm	61	99	159.94299(32)#	874+16 −12 ms^[2]	βべーた⁻	¹⁶⁰Sm
¹⁶¹Pm	61	100	160.94586(54)#	724+20 −12 ms^[2]	βべーた⁻ (98.91%)	¹⁶¹Sm	5/2−#
¹⁶¹Pm	61	100	160.94586(54)#	724+20 −12 ms^[2]	βべーた⁻, n (1.09%)	¹⁶⁰Sm	5/2−#
¹⁶²Pm	61	101	161.95029(75)#	467+38 −18 ms^[2]	βべーた⁻ (98.21%)	¹⁶²Sm
¹⁶²Pm	61	101	161.95029(75)#	467+38 −18 ms^[2]	βべーた⁻, n (1.79%)	¹⁶¹Sm
¹⁶³Pm	61	102	162.95368(86)#	362+42 −30 ms^[2]	βべーた⁻ (95%)	¹⁶³Sm	5/2−#
¹⁶³Pm	61	102	162.95368(86)#	362+42 −30 ms^[2]	βべーた⁻, n (1.79%)	¹⁶²Sm	5/2−#
¹⁶⁴Pm	61	103		280+38 −33 ms^[2]	βべーた⁻ (93.82%)	¹⁶⁴Sm
¹⁶⁴Pm	61	103		280+38 −33 ms^[2]	βべーた⁻, n (6.18%)	¹⁶³Sm
¹⁶⁵Pm	61	104		297+111 −101 ms^[2]	βべーた⁻ (86.74%)	¹⁶⁵Sm
¹⁶⁵Pm	61	104		297+111 −101 ms^[2]	βべーた⁻, n (13.26%)	¹⁶⁴Sm
¹⁶⁶Pm	61	105		228+131 −112 ms^[2]	βべーた⁻	¹⁶⁶Sm
¹⁶⁶Pm	61	105		228+131 −112 ms^[2]	βべーた⁻, n	¹⁶⁵Sm
This table header & footer: view

^ ^mPm – Excited nuclear isomer.
^ ( ) – Uncertainty (1σしぐま) 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

p: Proton emission
^ Bold italics symbol as daughter – Daughter product is nearly stable.
^ Bold symbol as daughter – Daughter product is stable.
^ ( ) spin value – Indicates spin with weak assignment arguments.
^ ^a ^b ^c Fission product
^ Spontaneous fission product of ²³²Th, ²³⁵U, ²³⁸U and alpha decay daughter of primordial ¹⁵¹Eu

Stability of promethium isotopes[edit]

Promethium is one of the two elements of the first 82 elements that has no stable isotopes. This is a rarely occurring effect of the liquid drop model. Namely, promethium does not have any beta-stable isotopes, as for any mass number, it is energetically favorable for a promethium isotope to undergo positron emission or beta decay, respectively forming a neodymium or samarium isotope which has a higher binding energy per nucleon. The other element for which this happens is technetium (Z = 43).

Promethium-147[edit]

Promethium-147 has a half-life of 2.62 years, and is a fission product produced in nuclear reactors via beta decay from neodymium-147. The isotopes ¹⁴²Nd, ¹⁴³Nd, ¹⁴⁴Nd, ¹⁴⁵Nd, ¹⁴⁶Nd, ¹⁴⁸Nd, and ¹⁵⁰Nd are either stable or nearly so, so the isotopes of promethium with those masses cannot be produced by beta decay and therefore are not fission products in significant quantities. ¹⁴⁹Pm and ¹⁵¹Pm have half-lives of only 53.08 and 28.40 hours, so are not found in spent nuclear fuel that has been cooled for months or years. It is found naturally mostly from the spontaneous fission of uranium-238 and less often from the alpha decay of europium-151.^[3]

Promethium-147 is used as a beta particle source and a radioisotope thermoelectric generator (RTG) fuel; its power density is about 2 watts per gram. Mixed with a phosphor, it was used to illuminate Apollo Lunar Module electrical switch tips and painted on control panels of the Lunar Roving Vehicle.^[4]

References[edit]

^ ^a ^b ^c 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.
^ ^a ^b ^c ^d ^e ^f ^g ^h Kiss, G. G.; Vitéz-Sveiczer, A.; Saito, Y.; et al. (2022). "Measuring the βべーた-decay properties of neutron-rich exotic Pm, Sm, Eu, and Gd isotopes to constrain the nucleosynthesis yields in the rare-earth region". The Astrophysical Journal. 936 (107): 107. Bibcode:2022ApJ...936..107K. doi:10.3847/1538-4357/ac80fc. hdl:2117/375253.
^ Belli, P.; Bernabei, R.; Cappella, F.; et al. (2007). "Search for αあるふぁ decay of natural Europium". Nuclear Physics A. 789 (1–4): 15–29. Bibcode:2007NuPhA.789...15B. doi:10.1016/j.nuclphysa.2007.03.001.
^ "Apollo Experience Report - Protection Against Radiation" (PDF). NASA. Archived from the original (PDF) on 14 November 2014. Retrieved 9 December 2011.

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
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.

[2] Pm – Excited nuclear isomer.

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

[TMS-4] # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).

[TNN-5] # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).

[6] Modes of decay:

EC: Electron capture

IT: Isomeric transition

p: Proton emission

[7] Bold italics symbol as daughter – Daughter product is nearly stable.

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

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

[FP-10] Fission product

[11] Spontaneous fission product of ²³²Th, ²³⁵U, ²³⁸U and alpha decay daughter of primordial ¹⁵¹Eu

[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.

[Ln922-12] ^ ^a ^b ^c ^d ^e ^f ^g ^h Kiss, G. G.; Vitéz-Sveiczer, A.; Saito, Y.; et al. (2022). "Measuring the βべーた-decay properties of neutron-rich exotic Pm, Sm, Eu, and Gd isotopes to constrain the nucleosynthesis yields in the rare-earth region". The Astrophysical Journal. 936 (107): 107. Bibcode:2022ApJ...936..107K. doi:10.3847/1538-4357/ac80fc. hdl:2117/375253.

[13] Belli, P.; Bernabei, R.; Cappella, F.; et al. (2007). "Search for αあるふぁ decay of natural Europium". Nuclear Physics A. 789 (1–4): 15–29. Bibcode:2007NuPhA.789...15B. doi:10.1016/j.nuclphysa.2007.03.001.

[14] "Apollo Experience Report - Protection Against Radiation" (PDF). NASA. Archived from the original (PDF) on 14 November 2014. Retrieved 9 December 2011.

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