Photoacoustic Signals from F Centers in Alkali Halide Crystals

Abstract

Photoacoustic (PA) signals due to the F centers formed by additive coloration are observed with a microphone-detection method. The result indicates that the PA signal is initially proportional to the optical absorption coefficient. Among several paths of de-excitation of the F centers, the non-radiative transition is considered to be mainly responsible for the PA signal. It is also confirmed that the saturation of the PA signal occurs at around the absorption coefficient refer to the optical thickness equivalent to the thermal thickness of the crystal.