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Autori: Bianca Gabel, Carola Kryschi, Slava Dremov, Vladimir Popov und Paul Müller
Editorial: DPG, 2002.
The surface morphology and optical properties of liquid crystal films doped with photochromic dithienylethene compounds are shown to be reversibly altered by photoirradiation. The photo- switching between two optical and structural states is based on the photochromism of the dithienylethene dopant which may exist as an open or as a closed isomer. While the open isomer has a twisted structure and exhibits an absorption spectrum in the uv, the absorption spectrum of the nearly planar closed isomer is shifted into the visible range. Photostimulating either the ring closure or the ring opening reaction is associated with large structural changes which may induce a phase transition of the liquid crystal matrix. The photoresponse of the surface morphology of different photochromic liquid crystals to uv and visible light has been mapped by atomic force microscopy.
Cuvinte cheie: photochromic compounds, liquid crystals, atomic force microscopy