NONLINEAR EXCITED-STATE ABSORPTION IN CADMIUM-PORPHYRIN-LIKE

Nonlinear absorption at 532 nm in a cadmium texaphyrin solution has be en studied using 8 ns and 23 ps laser pulses. The experiments show tha t reverse saturable absorption occurs in the nanosecond case. For pico second pulses, RSA occurs only at low fluences, and saturable absorpti on occurs at high fluences. A six-level model is proposed to explain t hese nonlinear absorption effects. Several photophysical parameters of excited states for cadmium texaphyrin, such as absorption cross-secti ons at 532 nm and lifetime, have been evaluated by fitting theoretical calculations with the experimental results.