Absorption wavelength dependent photodynamic motions in donor-acceptor type of azobenzene polymer films

Abstract

The dynamic properties of photoinduced molecular alignment and holographic inscription of surface relief gratings (SRG) were investigated depending on absorption wavelength of pi pi* and n pi* transition in donor-acceptor type of azopolymers, which contain different electron-withdrawing substituents [CF3, CN, CNCI, NO2, (CN)(2)] on the azobenzene. As the cis-n pi* absorption band approaches the excitation wavelength (488 nm), the photoinduced molecular alignment rapidly occurs. The rate of SRG formation was proportional to the rate of the photoinduced molecular alignment when the pi pi* absorption wavelength of the trans is higher than 440 nm.