Electronic spectroscopy, stimulated emission and persistent spectral hole-burning of cryogenic nitrogen matrices doped with tetrabenzoporphin

摘要

This paper deal with our on-going work on the electronic spectroscopy of tetrapyrrole molecules embedded inudcryogenic hosts. Under nanosecond laser excitation of the free-base tetrabenzoporphin molecules in a nitrogenudmatrix at 8 K, increasing the laser pulse energy results in essential enhancement of the intensity of one or severaludvibronic emission lines to take place in the fine-structure fluorescence spectrum. The observed intense monochromaticudradiation possesses characteristics of stimulated radiation being realized as a result of a transition fromudthe purely electronic S₁ level to a vibrational sublevel of the S₀ state, corresponding to excitation of stretching C–Cudvibrations of the tetrapyrrole methane bridges. We also report on persistent spectral hole-burning effects. Theudanalysis of the holes and antiholes formation gives some insight on the photochemical properties ofudtetrabenzoporphin in a nitrogen matrix.