Photochemical hole burning in macromolecular complexes

Photochemical hole burning (PHB) of free-base porphyrins in host polymers as a site-selective spectroscopy reveals the existence of vibronic structure in a porphyrin Q-band peak and low-energy excitation modes of host polymers. A new mechanism of photon-gated PHB by two-color sensitization of photoreactive polymers with a zinc porphyrin is also presented.