Determination of the bulk and surface absorption coefficients of highly transparent solids in the wavelength range of $CO_2$ laser radiation

coefficients of highly transparent solids, which were in the $10^{-4}-10^{-6}$ cm${}^{-1}$ range at wavelengths of $9,2-10,9\mu m$. A tunable $CO_2$ laser was used as the light source. The absorption spectra of cesium iodide crystals were determined.