MEASUREMENT OF THE VIBRATIONAL-RELAXATION TIME IN METAL-PHTHALOCYANINE SOLUTIONS

We report degenerate subpicosecond excite-probe experiments at a wavel ength close to the absorption peak of an excited vibrational state of two different metalphthalocyanine solutions. By using this technique, we were able to resolve in time the vibrational relaxation within the first electronic excited state of the molecule. A four-level model is used to explain the observed nonlinear response. Theoretical modeling allows us to obtain both the vibrational relaxation time, and two diff erent excited-state absorption cross-sections for each of the samples studied.