Time-resolved Raman spectroscopy of excited-state porphyrins

Time-resolved resonance Raman spectroscopy has been used to probe the lowest excited singlet and triplet states of free-base meso-tetraarylporphyrins. Both single-color and two-color time-resolved techniques have been used to probe the excited singlet states, while the triplet spectra were obtained in two-color experiments with a time-delay between pump and probe lasers of 30 ns. Marker bands for each of these three states have been identified. The information which qualitative analysis of the Raman spectra can give on the structural differences between these excited states is discussed.