Local Structure and Low-Temperature Dynamics of Glass State Probed by Hole Burning

Abstract

We measured hole burning properties of porphyrin dyes doped into polymer glasses. From the energy difference between zero-phonon holes and pseudo-phonon sideholes we could estimate low-energy excitation modes of host matrices. Irreversible increase of holewidth during temperature-cycling experiment agreed well with the relaxation behavior of each polymer, such as sidechain rotation. A mechanism of non-photochemical hole burning in polymers containing carboxylic acid was proposed from the deuterium effect and other results. We clarified the cause of laser-induced hole filling to be a non-siteselective excitation of a dye and discussed the important factor for inhomogeneous broadening, by burning holes at various wavelengths and temperatures.