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Isotopes of palladium

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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, California 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]

Standard atomic mass: 106.42(1) u

Palladium-103

Palladium-103 is a radioisotope of the element palladium which 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
Nuclide t1⁄2 Yield Q[a 1] βγ
(Ma) (%)[a 2] (keV)
99Tc 0.211 6.1385 294 β
126Sn 0.230 0.1084 4050[a 3] βγ
79Se 0.327 0.0447 151 β
135Cs 1.33  6.9110[a 4] 269 β
93Zr 1.53  5.4575 91 βγ
107Pd 6.5   1.2499 33 β
129I 16.14   0.8410 194 βγ
  1. ^ Decay energy is split among β, neutrino, and γ if any.
  2. ^ Per 65 thermal neutron fissions of 235U and 35 of 239Pu.
  3. ^ Has decay energy 380 keV, but its decay product 126Sb has decay energy 3.67 MeV.
  4. ^ Lower in thermal reactors because 135Xe, its predecessor, readily absorbs neutrons.

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)×106 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. ^ a b c d Theoretically capable of spontaneous fission
  6. ^ a b c d e 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

  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. ^ a b Winter, Mark. "Isotopes of palladium". WebElements. The University of Sheffield and WebElements Ltd, UK. Retrieved 4 March 2013.
  4. ^ http://www.platinummetalsreview.com/pdf/pmr-v35-i4-202-208.pdf
  5. ^ http://www.nucleonica.net/unc.aspx
  6. ^ Future Plan of the Experimental Program on Synthesizing the Heaviest Element at RIKEN, Kosuke Morita
  7. ^ a b Isomers in 128Pd and 126Pd: Evidence for a Robust Shell Closure at the Neutron Magic Number 82 in Exotic Palladium Isotopes; Physical Review Letters, 11/29/2013
  8. ^ a b Experiments on neutron-rich atomic nuclei could help scientists to understand nuclear reactions in exploding stars; physorg.com, 11/29/2013
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