Study of photoinduced orientation of azobenzene amorphous polymer by Visible, FTIR and Raman spectroscopy

Azo-dye containing polymeric systems have been a subject of intensive research in the last few years in the areas of photofunctional applications such as photon mode optical memories, transducing optical information, photoswitching of electron conductivity. The main interest of such doped or functionalized systems is due to their dichroic and birefringent properties when they are illuminated by a polarized light. Such an effect is a consequence of the reversible “trans↔cis” photoisomerisation with respect to the N=N double bond which causes a redistribution in the orientation of photochromic entities. In this respect, Dumont et al.1 have already reported the basis of a simple three-level theoretical model in order to explain the reorientation mechanisms of the azo molecules within a photoisomerisation cycle. Hereafter we thus report the results of a dynamical study of the photoisomerisation-induced reorientation of DR1-azo-dye in a polymer matrix (PMMA) by in-situ time dependent Visible and polarisation modulation FTIR spectroscopy measurements. The last part concerns the generation of high-efficiency diffraction patterns obtained by holographic way.