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Keywords:

Science & Technology, Physical Sciences, Chemistry, Multidisciplinary, Physics, Condensed Matter, Chemistry, Physics, 0204 Condensed Matter Physics, 0306 Physical Chemistry (incl. Structural), 0912 Materials Engineering, Physical Chemistry, 3402 Inorganic chemistry, 3403 Macromolecular and materials chemistry, 5104 Condensed matter physics

Abstract:

Mössbauer effect studies were performed on the nucleogenic 125Te and 129I monomers formed by the decay of their respective parents 125mTe and 129mTe embedded in solid argon at 4.2 K. Rare-gasmatrix-isolation (RGMI) and ion implantation techniques were combined to produce those extremely diluted Mössbauer emitters. The 125Te spectrum is composed of a quadrupole split component with splitting e2qQ 2 = 9.2(4) mm s and isomer shift IS = + 0.35(5) mm s, and a single line component with IS = +0.15(5) mm s with respect to a ZnTe absorber. They are attributed to Te0 and Te-1 species, respectively. The 129I spectrum is composed of a single quadrupole split component with e2qQ = -685(20) MHz and IS = +0.75(4) mm s with respect to a ZnTe source. This species is attributed to I0. Two novel single-line absorbers with high f values at RT were developed for the Te and I experiments, e.g. Mg3TeO6 and Na5IO6. Based on our results for Te0 and Te-1 and on relativistic Dirac-Slater atomic calculations, a new IS calibration curve under the form of a nonlinear relationship of IS versus the number of p holes (hp) in the closed shell configuration of 5s25p6 is established for 125Te. The IS data of the I0 monomer are used to refine the IS(hp) relationship for 129I. From these new calibration curves values are deduced for the change in mean-squared charge radius Δ〈r2〉 = 3.4(3) 10-3 fm2 for 125Te and Δ〈r2〉 = 19.9(7) 10-3 fm2 for 129I, respectively. The origin of the quadrupole interaction and the experimental features of this RGMI-implantation-Mössbauer emission spectroscopy are fully discussed. © 1985.