Singlet-singlet excited-state absorption and triplet-triplet absorption of meso-tetraphenylporphine

The singlet-singlet excited-state absorption cross-section spectrum and the triplet-triplet absorption cross-section spectrum of meso-tetraphenylporphine (H2TPP) are determined in the wavelength range from 390 to 1450 nm. The S-1-singlet state is populated by intense picosecond pump pulse absorption (wavelength 527 nm, duration 6 ps). The T-1-triplet state is populated by S-1-T-1 intersystem crossing. The singlet-singlet absorption and the triplet-triplet absorption are probed with picosecond spectral light continua passing the sample after appropriate time delays. Absolute singlet-singlet and triplet-triplet absorption cross-sections are obtained by numerical simulation of the absorption dynamics. The similarity of the S-1-band-and T-1-band-based excited-state absorption cross-section spectra indicate a strong higher excited-state spin-orbit coupling. (C) 2000 Elsevier Science B.V. All rights reserved.