Stars, stripes and shells in monolayers: simulation of the molecular arrangement in Schlieren structures

Abstract

Recent publications have reported on shell, star and stripe textures in monolayer films of long-chain fatty acids and esters at the air-water interface, observed with polarized fluorescence and Brewster angle microscopy (BAM). The difference in the brightness of the domains is related to a difference of the azimuthal tilt of the hydrocarbon chains of the molecules. We present model calculations concerning the various textures, observed by BAM using the 4 × 4 matrix algorithm of Berreman, J. Opt. Soc. Am., 62 (1972) 502–510. The calculations show that all observed textures are of splay type, with an azimuthal orientation directed to the inside of the shell or stripe in the case of a fatty acid and to the outside in the case of stars in methyl ester monolayers.