Raman Light Scattering Study of the Isotopic Construction Effects on the Lattice properties -TO and LO Phonon modes- of CuCl

This work expands on our research on isotope effects on phonons to include compound semiconductors. In this article, we concentrate our study on variation of the lattice properties such as lattice dynamics and electronic structure due to the effects of isotope substitution on the CuCl Raman spectra. We fulfilled that by examined 35Cl, 37Cl, 63Cu and 65Cu. Unlike elemental semiconductors, compounds whose constituents are isotopically substituted have a substantial dependence on the phonon branch and wave vector q for changes in phonon frequencies and atomic displacements. In the case of CuCl, the substitution of heavy or light atoms has distinct effects on the acoustic and visual branches of the phonon dispersion relations. The significant mass difference between copper and chlorine causes the eigenvectors of the acoustic vibrations to be dominated by copper displacements, while the optic vibrations are dominated by chlorine displacements. Consequently, the phonon frequencies in the visual and acoustic branches can be altered nearly independently, especially at the X point, by employing isotope replacement. At low temperatures, this enables us to examine the effectiveness of the anharmonic decay channels of Γ point optical phonons into lower-lying acoustic bands.