Isotopes of palladium

Naturally occurring palladium (Pd) is composed of six stable isotopes, ¹⁰²Pd, ¹⁰⁴Pd, ¹⁰⁵Pd, ¹⁰⁶Pd, ¹⁰⁸Pd, and ¹¹⁰Pd, although two of them are theoretically unstable. The most stable radioisotopes are ¹⁰⁷Pd with a half-life of 6.5 million years, ¹⁰³Pd with a half-life of 17 days, and ¹⁰⁰Pd with a half-life of 3.63 days. Twenty-three other radioisotopes have been characterized with atomic weights ranging from 90.949 u (⁹¹Pd) to 123.937 u (¹²⁴Pd). Most of these have half-lives that are less than a half an hour except ¹⁰¹Pd (half-life: 8.47 hours), ¹⁰⁹Pd (half-life: 13.7 hours), and ¹¹²Pd (half-life: 21 hours).

The primary decay mode before the most abundant stable isotope, ¹⁰⁶Pd, is electron capture and the primary mode after is beta decay. The primary decay product before ¹⁰⁶Pd is rhodium and the primary product after is silver.

Radiogenic ¹⁰⁷Ag is a decay product of ¹⁰⁷Pd and was first discovered in the Santa Clara meteorite of 1978.^[1] The discoverers suggest that the coalescence and differentiation of iron-cored small planets may have occurred 10 million years after a nucleosynthetic event. ¹⁰⁷Pd versus Ag correlations observed in bodies, which have clearly been melted since accretion of the solar system, must reflect the presence of short-lived nuclides in the early solar system.^[2]

Relative atomic mass: 106.42(1)

Palladium-103

Palladium-103 is a radioisotope of the element palladium that has uses in radiation therapy for prostate cancer and uveal melanoma. Palladium-103 may be created from palladium-102 or from Rhodium-103 using a Cyclotron. Palladium-103 has a half-life of 16.99^[3] days and decays by electron capture to rhodium-103, emitting gamma-rays with 21 keV of energy.

Palladium-107

Long-lived
fission products

Prop: Unit:	t½ (Ma)	Yield (%)	Q * (keV)	βγ *
^99Tc	0.211	6.1385	294	β
^126Sn	0.230	0.1084	4050	βγ
^79Se	0.327	0.0447	151	β
^93Zr	1.53	5.4575	91	βγ
^135Cs	2.3	6.9110	269	β
^107Pd	6.5	1.2499	33	β
^129I	15.7	0.8410	194	βγ
Hover underlined: more info

Palladium-107 is the second longest lived (halflife of 6.5 million years^[3]) and least radioactive (decay energy only 33 keV, specific activity 5×10⁻⁵ Ci/g) of the 7 long-lived fission products. It undergoes pure beta decay (no gamma radiation) to Ag-107.

Its yield from thermal neutron fission of uranium-235 is 0.1629% per fission, only 1/4 that of iodine-129, and only 1/40 those of Tc-99, Zr-93, and Cs-135. Yield from U-233 is slightly lower, but yield from Pu-239 is much higher, 3.3%. Yields are higher in fast fission or in fission of heavier nuclei.

According to ^[4] fission palladium contains the isotopes ¹⁰⁴Pd (16.9%),¹⁰⁵Pd (29.3%), ¹⁰⁶Pd (21.3%), ¹⁰⁷Pd (17%), ¹⁰⁸Pd (11.7%) and ¹¹⁰Pd (3.8%). According to another source, the proportion of ¹⁰⁷Pd is 9.2% for palladium from thermal neutron fission of U-235, 11.8% for U-233, and 20.4% for Pu-239. (and the Pu-239 yield of palladium is about 10 times that of U-235.)

Because of this dilution and because ¹⁰⁵Pd has 11 times the neutron absorption cross section, ¹⁰⁷Pd is not amenable to disposal by nuclear transmutation. However, as a noble metal, palladium is not as mobile in the environment as iodine or technetium.

Table

nuclide symbol	Z(p)	N(n)	isotopic mass (u)	half-life	decay mode(s)[5][n 1]	daughter isotope(s)[n 2]	nuclear spin	representative isotopic composition (mole fraction)	range of natural variation (mole fraction)
	excitation energy
^91Pd	46	45	90.94911(61)#	10# ms [>1.5 µs]	β^+	^91Rh	7/2+#
^92Pd	46	46	91.94042(54)#	1.1(3) s [0.7(+4−2) s]	β^+	^92Rh	0+
^93Pd	46	47	92.93591(43)#	1.07(12) s	β^+	^93Rh	(9/2+)
^93mPd	0+X keV			9.3(+25−17) s
^94Pd	46	48	93.92877(43)#	9.0(5) s	β^+	^94Rh	0+
^94mPd	4884.4(5) keV			530(10) ns			(14+)
^95Pd	46	49	94.92469(43)#	10# s	β^+	^95Rh	9/2+#
^95mPd	1860(500)# keV			13.3(3) s	β^+ (94.1%)	^95Rh	(21/2+)
					IT (5%)	^95Pd
					β^+, p (.9%)	^94Ru
^96Pd	46	50	95.91816(16)	122(2) s	β^+	^96Rh	0+
^96mPd	2530.8(1) keV			1.81(1) µs			8+
^97Pd	46	51	96.91648(32)	3.10(9) min	β^+	^97Rh	5/2+#
^98Pd	46	52	97.912721(23)	17.7(3) min	β^+	^98Rh	0+
^99Pd	46	53	98.911768(16)	21.4(2) min	β^+	^99Rh	(5/2)+
^100Pd	46	54	99.908506(12)	3.63(9) d	EC	^100Rh	0+
^101Pd	46	55	100.908289(19)	8.47(6) h	β^+	^101Rh	5/2+
^102Pd	46	56	101.905609(3)	Observationally Stable[n 3]			0+	0.0102(1)
^103Pd[n 4]	46	57	102.906087(3)	16.991(19) d	EC	^103Rh	5/2+
^103mPd	784.79(10) keV			25(2) ns			11/2−
^104Pd	46	58	103.904036(4)	Stable[n 5]			0+	0.1114(8)
^105Pd[n 6]	46	59	104.905085(4)	Stable[n 5]			5/2+	0.2233(8)
^106Pd[n 6]	46	60	105.903486(4)	Stable[n 5]			0+	0.2733(3)
^107Pd[n 7]	46	61	106.905133(4)	6.5(3)×10^6 a	β^−	^107Ag	5/2+
^107m1Pd	115.74(12) keV			0.85(10) µs			1/2+
^107m2Pd	214.6(3) keV			21.3(5) s	IT	^107Pd	11/2−
^108Pd[n 6]	46	62	107.903892(4)	Stable[n 5]			0+	0.2646(9)
^109Pd[n 6]	46	63	108.905950(4)	13.7012(24) h	β^−	^109mAg	5/2+
^109m1Pd	113.400(10) keV			380(50) ns			1/2+
^109m2Pd	188.990(10) keV			4.696(3) min	IT	^109Pd	11/2−
^110Pd[n 6]	46	64	109.905153(12)	Observationally Stable[n 8]			0+	0.1172(9)
^111Pd	46	65	110.907671(12)	23.4(2) min	β^−	^111mAg	5/2+
^111mPd	172.18(8) keV			5.5(1) h	IT	^111Pd	11/2−
					β^−	^111mAg
^112Pd	46	66	111.907314(19)	21.03(5) h	β^−	^112Ag	0+
^113Pd	46	67	112.91015(4)	93(5) s	β^−	^113mAg	(5/2+)
^113mPd	81.1(3) keV			0.3(1) s	IT	^113Pd	(9/2−)
^114Pd	46	68	113.910363(25)	2.42(6) min	β^−	^114Ag	0+
^115Pd	46	69	114.91368(7)	25(2) s	β^−	^115mAg	(5/2+)#
^115mPd	89.18(25) keV			50(3) s	β^− (92%)	^115Ag	(11/2−)#
					IT (8%)	^115Pd
^116Pd	46	70	115.91416(6)	11.8(4) s	β^−	^116Ag	0+
^117Pd	46	71	116.91784(6)	4.3(3) s	β^−	^117mAg	(5/2+)
^117mPd	203.2(3) keV			19.1(7) ms	IT	^117Pd	(11/2−)#
^118Pd	46	72	117.91898(23)	1.9(1) s	β^−	^118Ag	0+
^119Pd	46	73	118.92311(32)#	0.92(13) s	β^−	^119Ag
^120Pd	46	74	119.92469(13)	0.5(1) s	β^−	^120Ag	0+
^121Pd	46	75	120.92887(54)#	400# ms [>300 ns]	β^−	^121Ag
^122Pd	46	76	121.93055(43)#	300# ms [>300 ns]	β^−	^122Ag	0+
^123Pd	46	77	122.93493(64)#	200# ms [>300 ns]	β^−	^123Ag
^124Pd	46	78	123.93688(54)#	100# ms [>300 ns]			0+
^125Pd[6]	46	79
^126Pd[7][8]	46	80					0+
^126m1Pd	2023 keV			330 ns	IT	^126Pd	5-
^126m2Pd	2110 keV			440 ns	IT	^126m1Pd	7-
^128Pd[7][8]	46	82					0+
^128mPd	2151 keV			5.8 µs	IT	^128Pd	8+

1. Abbreviations:
   EC: Electron capture
   IT: Isomeric transition
2. Bold for stable isotopes
3. Believed to decay by β⁺β⁺ to ¹⁰²Ru
4. Used in medicine
5. Theoretically capable of spontaneous fission
6. Fission product
7. Long-lived fission product
8. Believed to decay by β⁻β⁻ to ¹¹⁰Cd with a half-life over 6×10¹⁷ years

Notes

• The precision of the isotope abundances and atomic mass is limited through variations. The given ranges should be applicable to any normal terrestrial material.
• Geologically exceptional samples are known in which the isotopic composition lies outside the reported range. The uncertainty in the atomic mass may exceed the stated value for such specimens.
• 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

• Patent application for Palladium-103 implantable radiation-delivery device (accessed 12/7/05)

1. W. R. Kelly; G. J. Wasserburg (1978). "Evidence for the existence of ¹⁰⁷Pd in the early solar system". Geophysical Research Letters. 5 (12): 1079–1082. Bibcode:1978GeoRL...5.1079K. doi:10.1029/GL005i012p01079.
2. J. H. Chen; G. J. Wasserburg (1990). "The isotopic composition of Ag in meteorites and the presence of ¹⁰⁷Pd in protoplanets". Geochimica et Cosmochimica Acta. 54 (6): 1729–1743. Bibcode:1990GeCoA..54.1729C. doi:10.1016/0016-7037(90)90404-9.
3. Winter, Mark. "Isotopes of palladium". WebElements. The University of Sheffield and WebElements Ltd, UK. Retrieved 4 March 2013.
4. R. P. Bush (1991). "Recovery of Platinum Group Metals from High Level Radioactive Waste" (PDF). Platinum Metals Review. 35 (4): 202–208.
5. "Universal Nuclide Chart". nucleonica. (registration required (help)).
6. Future Plan of the Experimental Program on Synthesizing the Heaviest Element at RIKEN, Kosuke Morita Archived September 17, 2012, at the Wayback Machine.
7. H. Watanabe; et al. (2013-10-08). "Isomers in ¹²⁸Pd and ¹²⁶Pd: Evidence for a Robust Shell Closure at the Neutron Magic Number 82 in Exotic Palladium Isotopes". Physical Review Letters. 111: 152501. doi:10.1103/PhysRevLett.111.152501.
8. "Experiments on neutron-rich atomic nuclei could help scientists to understand nuclear reactions in exploding stars". phys.org. 2013-11-29.

• 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. Check date values in: |access-date= (help)
  • 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.