Primary photoprocesses in real-time holographic recording material: dichromated poly(vinyl alcohol)

Dichromated Poly(vinyl alcohol) films with and without dyes and electron donor have been employed for real-time holographic recording and for the fabrication of holographic optical elements (HOEs). The primary photoprocess of the interaction of Cr(VI) with the polymer has been followed under various experimental conditions through esr spectroscopy. The effect of the pH of the coating solution, concentration of dichromate, electron donor and dyes on the evolution of intermediates has been discussed. A suitable mechanism involving the electron transfer from the polymer to Cr(VI) leading to the formation of Cr(V) and polymer radical, which further undergoes reaction to produce Cr(III) and crosslinked polymer matrix, has been suggested.