Abstract:
The pressure dependence of the resonance frequency of several RUS modes in samples of fused silica and KCl has been measured at UCLA in atmospheres of air, He, and Ar near ambient temperature. For both compressional and torsional modes the radiation resistance appears to be linearly dependent upon pressure and increases with the molecular mass of the surrounding gas. The effects are larger for breathing modes than for torsional modes. A model will be presented which will attempt to fit some of these data both qualitatively and quantitatively. [Work supported by the Office of Naval Research.]