Grazing incidence X-ray reflectivity of coumarin side-chain polymers used for liquid crystal photoalignment layers
| Autor: | Stephen M. Kelly, G. Bergmann, P. O. Jackson, J. H. C. Hogg, Mary O'Neill, G. F. Clark, Paul Hindmarsh |
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| Rok vydání: | 2002 |
| Předmět: |
Materials science
business.industry Plane of incidence Mechanical Engineering Metals and Alloys Surface finish Condensed Matter Physics medicine.disease_cause Electronic Optical and Magnetic Materials X-ray reflectivity Condensed Matter::Materials Science Optics Mechanics of Materials Liquid crystal Condensed Matter::Superconductivity Materials Chemistry Surface roughness medicine Ultraviolet light Specular reflection business Ultraviolet |
| Zdroj: | Synthetic Metals. 127:95-98 |
| ISSN: | 0379-6779 |
| DOI: | 10.1016/s0379-6779(01)00606-3 |
| Popis: | Specular X-ray reflectivity measurements are used to examine photoinduced surface roughness of side-chain coumarin polymers that form liquid crystal photoalignment layers. Thin films were irradiated with polarised or unpolarised ultraviolet light and the X-ray reflectivity at grazing incidence was measured for samples irradiated with different ultraviolet fluences. Kiessig fringes are observed over a large dynamic range and a comparison of the measured and calculated reflectivity gives a value for the surface roughness. The photoinduced roughness increases with ultraviolet fluence, from 5.5 to 20 A. Negligible photoinduced roughness is detected for a film, which was previously irradiated using conditions that give strong planar liquid crystal alignment. Specular reflectivity data taken with the plane of incidence of the X-ray parallel and perpendicular to the polarisation direction of the ultraviolet light are identical within experimental uncertainty. Hence in-plane anisotropic surface roughness is not observed. |
| Databáze: | OpenAIRE |
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