QUANTUM-THEORY AND EXPERIMENTAL STUDIES OF ABSORPTION-SPECTRA AND PHOTOISOMERIZATION OF AZOBENZENE POLYMERS

The microscopic properties of azobenzene chromophores are important fo r a correct description of optical storage systems based on photoinduc ed anisotropy in azobenzene polymers. A quantum model of these propert ies is presented and verified by comparison to experimental absorption spectra for trans and cis isomers of cyano methoxy azobenzene. In add ition, the trans --> cis quantum efficiency is measured, and hence the combined experimental and theoretical work allows one to determine th e essential molecular properties, including magnitude and anisotropy o f the absorption cross section and various components of the polarizab ility tensor for both trans and cis isomers. It is shown that the tran s isomer is almost perfectly anisotropic, whereas the cis isomer is ap proximately isotropic in the plane containing the central C-N=N-C azob ridge. The implications for models of the storage mechanism are discus sed. (C) 1998 Optical Society of America [S0740-3224(98)02109-2].