Reversible Photochromic Behaviors of Fatty Acids with Azobenzene Chromophore in Thin Film Assemblies

The mechanism of reversible photoinduced anisotropy of an azobenzene derivative was investigated by measuring optical retardation and UV/Vis dichroism. During the relaxation period, the cis-trans thermal back relaxation and orientational relaxation of azobenzene groups occur. It is believed that the orientational relaxation of trans and cis azobenzene groups to relieve the strains is a more dominant contribution to the decrease of the optical anisotropy in the film.