Sol-gel hosts doped with porphyrin derivatives. Part I. Spectroscopy, hole-burning and spectral diffusion Original Research Article

Pure inorganic sol-gel matrices as well as hybrid organic/inorganic xerogels have been doped with porphyrins derivatives and studied using line narrowing techniques. The role of residual hydroxyl groups is investigated. Free-base porphyrins are protonated in pure inorganic hosts, but the matrix acidity is reduced in hybrid matrices or when fluorinated porphyrins derivatives are used. The linear electron-phonon coupling can be controlled with the choice of the organic group in organic/inorganic matrices. Persistent spectral hole widths increase with temperature according a glass-like Tn dependence and evidence of spectral diffusion is shown in one of these systems.