Ultrafast Internal Conversion and Vibrational Relaxation of Butylphthalocyanine and Tetraphenylporphyrin in Solution

Abstract

ultrafast internal conversion (ic) and vibrational relaxation dynamics of electronically excited butylphthalocyanine (bupc) and tetra-phenylporphyrin (tpp) molecules in solution are theoretically studied on the basis of the perturbative density operator method and the transient linear susceptibility theory. femtosecond time-resolved profile of fluorescence depletion is simulated with a single vibrational mode. the internal conversion, the vibrational relaxation and the solvation rate constants in electronically excited states are determined. the results show that the sharp peak of fluorescence depletion reflects primarily the internal conversion process from the s-2 state to the s-1 state of bupc and tpp. ic occurs in a 200 fs time scale.