PHOTOTHERMAL DYNAMICS AT THE SURFACE OF COPPER PHTHALOCYANINE SOLID REVEALED BY TIME-RESOLVED REGULAR REFLECTION SPECTROSCOPY

Flat surfaces of compressed pellets made of copper phthalocyanine powd ers were excited by nanosecond laser pulses and their time-resolved ex tinction coefficients were obtained by using regular I reflection spec troscopy independent of Kramers-Kronig transformation. The results sho wed transient depletion at the peaks of the ground state absorption sp ectra, which is due to a change in thermal population in vibrational s tates. The decay of the transient depletion was well described with th e temperature dependency of extinction coefficient based on Sulzer-Wie land approximation and one-dimensional thermal diffusion towards the d eep parts of the pellet samples.