Photo orientation of azo dye molecules in glassy o-terphenyl

A study was made of the formation of optical absorption anisotropy over the temperature range of 231.5–244 K in o-terphenyl, doped with an azo dye under linearly polarized light irradiation. The reorientation of dye molecules results from a succession of isomerization acts. The direction of a transition dipole upon isomerization for most of the molecules changes by angle of several degrees. A small fraction of molecules is characterized by a greater turn angle of approximately 37°.