PHOTOKINETICS IN PHOTOCHROMIC POLYMERS STUDIED BY HOLOGRAPHIC RECORDING

Photokinetic processes in photochromic polymers are studied by holographic recording. A semiempirical model for elucidating the photochemical and thermal transformations between the colorless and colored forms of photochromic compounds is presented. In this model, holographic recording in the visible range by bleaching of precolored material is emphasized. The model calculations are compared with the experimental exposure responses of holographic gratings recorded in spirooxazine containing polymer films. The results exhibit significant differences in the holographic exposure response with variations in the exposure configurations, suggesting that the thermal and photochemical transformations occur between colorless spirooxazine and at least two stereoisomeric forms of colored merocyanine dye.