The compression induced change of the integral reflected intensity of an ar
achidic acid Langmuir film at the Brewster angle - the so-called reflection
isotherm - is analysed to get information about the in-plane anisotropy of
the Langmuir film caused by compression and expansion cycles. Based on the
matrix method of Berreman a theoretical model, connecting the shape of the
reflection isotherms with the domain orientation distribution in the monof
ilm, is developed. Furthermore, the influence of different counter-ions on
the reflection isotherms is studied. The data indicate the formation of ion
-specific domain orientation distributions (textures). The reflection isoth
erms are sensitive to changes in the Langmuir films supramolecular structur
e which are not reflected by the surface pressure-area isotherms. (C) 2000
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