Temperature dependence of the dielectric permittivity of CaF(2), BaF(2) and Al(2)O(3): application to the prediction of a temperature-dependent van der Waals surface interaction exerted onto a neighbouring Cs(8P(3/2)) atom.

The temperature behaviour in the range 22-500 °C of the dielectric permittivity in the infrared range is investigated for CaF(2), BaF(2) and Al(2)O(3) through reflectivity measurements. The dielectric permittivity is retrieved by fitting reflectivity spectra with a model taking into account multiphonon contributions. The results extrapolated from the measurements are applied to predict a temperature-dependent atom-surface van der Waals interaction. We specifically consider as the atom of interest Cs(8P(3/2)), the most relevant virtual couplings of which fall in the range of thermal radiation and are located in the vicinity of the reststrahlen band of fluoride materials.