Studies On Orientation Of Organic Fluorescent Dyes In Stretched Polymer Films

Abstract

We present a method for immobilizing and orienting organic fluorescent dyes in transparent poly(vinyl alcohol) (PVA) matrix. Dyes were introduced into the water solution of PVA that was slowly dried in a Petri dish, thus forming a uniform thin polymer film that trapped dye molecules in a rigid polymer matrix. These films were stretched up to 4-folds compared to their original length, a process thatwas very effectively oriented organic molecules in between aligned polymeric chains. Such immobilized and oriented molecules were used for studying the direction of electronic transition moment. Structure of transition moments in the molecular framework is one of the fundamental properties of a molecular system responsible for its interaction with light and other molecules. Spectroscopic properties such as absorption, emission, and excitation were measured with both vertical and horizontal light polarization as compare to the stretching direction of the film. A mathematical model was used to analyze observed dichroism and to determine directions of absorption and emission transition moments. Different concentration of each particular fluorescence dye in the PVA film was also be studied.