Photochromic Indigoids III: A Photochromic Element Based on the cis–trans Photoisomerization of a Thioindigo Dye

Abstract

The dynamic properties of a photochromic element consisting of a substituted thioindigo dye dissolved in a heat-cured epoxy resin are shown to be calculable from an accurate knowledge of the absorption spectra of the cis and trans isomers of the dye and the quantum yields for the photoisomerization process. When the dye is a 6,6'-di-alkoxythioindigo, such an element appears well suited for storage and readout of optical information using the argon-ion laser.