Accession Number : ADA306622

Title :   Optically-Inscribed High Efficiency Diffraction Gratings in Azo Polymer Films.

Descriptive Note : Technical rept.,

Corporate Author : QUEEN'S UNIV KINGSTON (ONTARIO) DEPT OF CHEMISTRY

Personal Author(s) : Barrett, C. ; Natansohn, A. ; Rochon, P.

PDF Url : ADA306622

Report Date : 28 MAR 1996

Pagination or Media Count : 3

Abstract : A series of amorphous azobenzene-containing polymers were cast as thin films and shown to produce both reversible volume diffraction gratings and high-efficiency surface gratings by laser irradiation at an absorbing wavelength. The latter process involves localized mass transport of the polymer chains to a high degree, as atomic force microscopy reveals surface profile depths near that of the original film thickness. A mechanism for this phenomenon is proposed which involves pressure gradients as a driving force, present due to different photochemical behaviors of the azo chromophores at different regions of the interference pattern. This mechanism of photoinduced viscoelastic flow agrees well with the results of experiments investigating the effect of the polarization state of the interfering writing beams and the photochemical behavior of the chromophore, the free volume requirements of the induced geometric changes, and the viscoelastic flow of the material.

Descriptors :   *PHOTOCHEMICAL REACTIONS, *POLYMERS, PRESSURE GRADIENTS, CHROMOPHORES, VISCOELASTICITY, THIN FILMS, MASS TRANSFER, POLYMERIC FILMS, IRRADIATION.

Subject Categories : Radiation and Nuclear Chemistry

Distribution Statement : APPROVED FOR PUBLIC RELEASE