title: Formation mechanism and dynamics in polymer surface gratings.
abstract: We present the results of time-dependent x-ray and visible light (VIS) scattering measurements during formation of surface relief grating (SRG). These gratings are formed on polymer films containing azobenzene side groups during pulselike exposure with a holographic pattern of circularly polarized light at 488 nm. The SRG formation is accompanied by a density grating just below the film surface. Assuming viscoelastic flow, a change in polymer's elastic properties upon light exposure can explain the massive material transport. Finite element calculations reveal a dynamic model of grating formation characterized by different relaxation times. The simultaneous formation of a surface relief grating and of a density grating explains quantitatively the findings of the VIS experiment, but only qualitatively the findings of the x-ray measurements.
authors.affiliation: Institute of Physics, University of Potsdam, P.O.B. 601553, Potsdam, D-14415 Germany.
authors.forename: T M
authors.initials: TM
authors.lastname: Geue
authors.forename: M G
authors.initials: MG
authors.lastname: Saphiannikova
authors.forename: O
authors.initials: O
authors.lastname: Henneberg
authors.forename: U
authors.initials: U
authors.lastname: Pietsch
authors.forename: P L
authors.initials: PL
authors.lastname: Rochon
authors.forename: A L
authors.initials: AL
authors.lastname: Natansohn