Singlet–singlet excited-state absorption and triplet–triplet absorption of meso-tetraphenylporphine Original Research Article

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 S1-singlet state is populated by intense picosecond pump pulse absorption (wavelength 527 nm, duration 6 ps). The T1-triplet state is populated by S1–T1 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 S1-band-and T1-band-based excited-state absorption cross-section spectra indicate a strong higher excited-state spin–orbit coupling.