Dispersion of Surface and Bulk Phonon‐Polaritons on α‐Quartz Measured by Attenuated Total Reflection

Abstract In a continuation of the study of surface polaritons with “stop points” on α‐quartz, experimental ATR spectra for various thicknesses of the air gap between prism and α‐quartz sample were compared to theoretical ones. The relations between surface polaritons, stop points, anisotropic reststrahlen bands, longitudinal phonons, and bulk polaritons were studied. It is shown that the dispersion of bulk polaritons may be measured by ATR as well as the dispersion of surface polaritons. Results are presented for the dispersion of two bulk polaritons, one of which is Raman‐inactive.