Abstract
We analyse the infrared ellipsometric spectra of α-quartz in the wavenumber range 430 to 1350cm−1. We discuss the phenomenology of obliquely reflected light in order to understand the spectral shapes related to narrow phonon lines. The line shapes of the transverse resonances and their longitudinal counterparts are compared with the model of classical oscillators. The quantitative data are found to be in agreement with the decomposition of the dispersion in the transparent region into the electronic and vibronic contributions.