Photonic applications of azo compounds often require to know the polarization of molecular absorption bands. In this study, we demonstrate how the kinetics of light-induced anisotropy can be used to determine the mutual orientation of transition dipole moments pertaining to different absorption bands of an azo compound. The time profiles of light-induced anisotropy of the polymeric films doped with azo compounds p-azotoluene (AT) and 1-naphthyl-p-azo-methoxybenzene (NAMB) are analysed using commonly accepted models of photo-orientation. It is found that under irradiation of the films containing NAMB in the n → π* band of NAMB, the anisotropy level is too low compared to the anisotropy formed under irradiation in the π → π* band. The data are interpreted as demonstrating that the dipole moments of the n → π* and π → π* transitions of the NAMB molecule are not collinear. The angle between them was estimated to be 32.5 ± 5°.
|Журнал||Journal of Photochemistry and Photobiology A: Chemistry|
|Состояние||Опубликовано - 1 июл 2017|