%0 Journal Article
%T AFM Height Measurements of Molecular Layers of a Carbocyanine Dye
%A Valery V. Prokhorov
%A Sergey I. Pozin
%A Dmitry A. Lypenko
%A Olga M. Perelygina
%A Eugene I. Mal¡¯tsev
%A Anatoly V. Vannikov
%J World Journal of Nano Science and Engineering
%P 67-72
%@ 2161-4962
%D 2011
%I Scientific Research Publishing
%R 10.4236/wjnse.2011.13010
%X Atomic force microscopy (AFM) was used for the morphological characterization and precise height meas-urements of two-dimensional molecular layers of carbocyanine dye 3,3¡¯-di(r-sulfopropyl)-4,4¡¯,5,5¡¯-dibenzo-9-ethylthiacarbocyanine betaine pyridinium salt. The AFM measurements reveal three morphological types of molecular aggregates: leaves, stripes and spots. The leaves are stripes have same monolayer height ~1.4 nm and different crystal shapes: the leaves are monoloyers with the lens shape and the stripes are bilay-ers with the shape of extended rectangles. The monolayer height ~1.4 nm was interpreted as indicating the symmetrical packing arrangement of dye molecules. In the symmetrical monolayer, the sulfopropyl groups of all-trans monomer units are located on both monolayer sides whereas the adjacent stacked dye molecules have a lateral slippage providing the J-aggregate optical properties. The lower height of spots ~1 nm was explained by the model of an asymmetric monolayer with sulfopropyl groups of all-trans monomers occupy-ing the same position with respect to the monolayer plane. The packing arrangement of all-trans monomers in the asymmetric monolayer corresponds to H-aggregate. The alternative models of the packing arrange-ment in monolayers with mono-cis1 monomer configuration are discussed.
%K Atomic Force Microscopy
%K J-Aggregates
%K H-Aggregates
%K Monolayers
%U http://www.scirp.org/journal/PaperInformation.aspx?PaperID=7504