Evidence of concerted inversion for the photon-induced molecular switching of azobenzene using rotation-free azobenzene derivatives

Ya-Wei Hao, Hai-Yu Wang, You-Ju Huang, Bing-Rong Gao, Qi-Dai Chen, Liang-Bin Li, Hong-Bo Sun
2013 Journal of Materials Chemistry C  
The excited state relaxation of two types of azobenzene derivative excited at 350 nm in the shortwavelength (S 2 (p, p*)) band was studied by transient absorption spectroscopy. We compared the relaxation dynamics and the time-resolved anisotropic relaxation properties of these two molecules in liquid solution and in bulk film. The average relaxation life-time for Azo-2 in bulk film (13.2 ps) is much slower than that of Azo-2 (4.06 ps) and Azo-1(1.31 ps) in liquid solution. The time-resolved
more » ... rization anisotropy spectroscopy measurements of these samples also showed significant differences. The value of anisotropy for Azo-2 remained almost constant at about 0.2 in bulk film but decayed slowly from 0.3 in liquid solution. The value for Azo-1 in liquid solution decayed very fast from 0.4 to 0.2 within 6 ps. Our results gave new evidence for the existence of a converted inversion channel. We also concluded that the concerted inversion process and the conventional rotation process govern the relaxation for the photon-induced switches of azobenzene and its derivatives under short-wavelength band excitation.
doi:10.1039/c3tc30879k fatcat:hmnk4djfifh6hizdupknmwny3q