Synchrotron radiation studies of beryllium fluoride glass

Beryllium fluoride glasses are possible materials for high power laser systems because of their low nonlinear refractive indexes. In addition the linear refractive index of BeF2 is extremely small, so that it may be of use in multilayer coatings for the ultraviolet. Reflectance of pure BeF2 glasses in the range 9 eV to 120 eV, as well as photoelectron spectra of the bulk glass in the valence band region were measured. Ultraviolet reflectivity and photoemission are useful measurements for indicating the ultimately achievable transmission edge since they sample very high densities of states, assumed intrinsic in nature. Both methods probe only the near surface region, so the hygroscopic nature of BeF2 presents a problem. An argon sputter etching gun was used to clean the samples in ultrahigh vacuum prior to measurement.