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CPP: Chemische Physik und Polymerphysik

CPP 11: Dünne Filme, Monolagen und Oberfl
ächen

CPP 11.7: Vortrag

Mittwoch, 13. März 2002, 15:30–15:50, H38

AFM study of photostimulated structural changes of liquid crystal surfaces — •Bianca Gabel¹, Carola Kryschi¹, Slava Dremov², Vladimir Popov², and Paul M"uller² — ¹Institut f"ur Physikalische Chemie I, FAU, Egerlandstr.3, 91058 Erlangen — ²Lehrstuhl f"ur Experimentalphysik III, FAU, Erwin-Rommel-Str.1, 91058 Erlangen

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.