Quantum Chemical Investigation of the Doppler Broadening of Positron Annihilation Radiation Spectra in Polymers

Katsuhiko Koyanagi ； Yukiumi Kita ； Kiminori Sato ； Yoshinori Kobayashi ； Masanori Tachikawa

《Chinese Journal of Physics》 51卷6期 (2013/12) Pp. 1205-1217

https://doi.org/10.6122/CJP.51.1205

並列摘要

In order to elucidate the element specificity of the S parameters of polymers containing C, O, or F atoms reported by Sato et al. with the Doppler broadening of positron annihilation radiation measurement [K. Sato, et al., Phys. Rev. B 71, 012201, (2005).], we theoretically analyzed the molecular orbitals of small size of the polymer molecules with an ab initio molecular orbital method. With a linear regression analysis, we found a strong correlation between the average kinetic energies of the valence electrons and the contribution of a free positron to the experimental S parameters for the C-, O-, and F-groups. As with a consideration of the kinetic energies of the valence electrons and the electronegativity of the C, O, and F atoms, we conclude that the element specificity of the experimental S parameters for each of the C-, O-, and F-groups is roughly explained by a difference in the electronegativity of the C, O, and F atoms.

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