Extrinsic absorption in KCl and KBr at CO2 laser frequencies

摘要

Extrinsic absorption has been studied in KCl and KBr using the technique of tunable CO2 laser calorimetry. The transparency of these hosts is limited by an extrinsic absorption mechanism common to both KCl and KBr. In particular, an extrinsic absorption band near 9.6 μm in both materials has been studied in detail. The features of this band are compared to a recent theory on impurity induced absorption at CO2 wavelengths. A bulk absorption in KBr of 1×10-5 cm-1 at 10.6 μm was measured for the best sample—the lowest value observed to date for any material at this frequency.