title: Monolayer alignment on azobenzene surfaces during UV light irradiation: analysis of optical polarized absorption measurement results and theoretical treatment.
abstract: The influence of the charge separation during the trans-cis conformational change on the surface of azobenzene 6Az10PVA monolayer on the polar liquid-crystal monolayer film, such as 4-n-pentyl-4'-cyanobiphenyl(5CB), is investigated. The effective anchoring energy (in the Rapini-Papolar form) is phenomenologically described in the framework of the molecular model, which takes into account the interaction between the surface polarization and surface electric field, for number of conformational states of the boundary surface. It is shown, using the experimental data for the voltage across the 6Az10PVA+5CB film, provided by the surface-potential technique, that the charge separation during the conformational changing, caused by the UV irradiation, may lead to changing of the surface alignment of liquid-crystalline molecules. The influence of the photoisomerization process on the orientational order parameter S2(t) using the optical polarized absorption measurement is also investigated.
authors.affiliation: Saint Petersburg Institute for Machine Sciences, the Russian Academy of Sciences, Saint Petersburg 199178, Russia. alexandre.zakharov@fys.kuleuven.ac.be
authors.forename: A V
authors.initials: AV
authors.lastname: Zakharov
authors.forename: Dai
authors.initials: D
authors.lastname: Taguchi
authors.forename: Takaaki
authors.initials: T
authors.lastname: Manaka
authors.forename: Mitsumasa
authors.initials: M
authors.lastname: Iwamoto