A general method for determining true acoustic-mode linewidths from Brillouin scattering data is presented. The method is specifically applied to diamond anvil cell experiments to obtain accurate hypersonic attenuation data at high pressure. This work was motivated by the noticeable lack of acoustic attenuation data at high pressure in the literature and by our own attempts to obtain relaxation data from Brillouin experiments in the diamond anvil cell. A detailed discussion of both instrumental and finite aperture contributions to the measured acoustic-mode linewidth is given, as well as specific algorithms for calculating these effects. Fits to Brillouin scattering spectra obtained at high pressures in different organic liquids are shown. Finally, a discussion is given of experimental details for obtaining accurate Brillouin linewidths in high-pressure diamond anvil cell experiments.
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