Molecular rotation in organized media: surface monolayers, liquid crystals and micelles

Abstract

Molecular rotation in ordinary liquids is generally understood, albeit imperfectly. However, molecular rotation in more complicated and intriguing media, such as surface monolayers, liquid crystals and organized surfactants, is less understood. These media are structured, thus affecting the way a solute rotates. To study molecular rotation, the correlation of the orientations of 2 transition dipoles of a solute is measured as a function of time. The results are interpreted using the spherical harmonics to describe the decay of the correlation function. The keys to describing rotation in complicated media are 1) highly quantitative and sensitive measurements of the rotational correlation function and 2) development of mathematical models to describe hindered rotation. In this paper, the rotational behavior of solute probes in bonded chromatographic phases, micelles and liquid crystals is described and contrasted with rotational behavior in ordinary liquids.