Pressure-tuning of anharmonic Raman line-shapes in 64Zn34S, 68Zn32S, and natural ZnS
Abstract
We compare and contrast the effects of applied pressure on the TO(Γ ) and LO (Γ ) Raman line-shapes in three varieties of cubic ZnS prepared to contain the isotopic compositions ^64Zn^34S, ^68Zn^32S, and natural ZnS. Raman spectra are measured as a function of applied hydrostatic pressures up to 15GPa using diamond-anvil cells at room and 16K temperatures. The most striking effects occur in the ^68Zn^32S sample, where the TO(Γ ) peak (at 16K) increases in intensity and narrows by factors of 10 and 5, respectively, as pressure shifts the TO(Γ ) frequency into a two-phonon density-of-states gap above the TA+LA continuum. In all the samples, the observed changes in the TO(Γ ) and LO(Γ ) line shapes can be understood using adiabatic bond-charge model calculations of the phonon density-of-states, combined with the measured mode Gruneisen constants and a second order perturbation treatment of the anharmonic coupling.
- Publication:
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APS March Meeting Abstracts
- Pub Date:
- March 2004
- Bibcode:
- 2004APS..MARA11010T