SPECTRAL-LUMINESCENT STUDY OF ORIENTATION STATES OF DYE MOLECULES ADSORBED ON A NONUNIFORM SURFACE

Brownian reorientation motion of molecules results in an equilibrium of orientation states of adsorbed molecules. The character of the orientation equilibrium depends on the total concentration of adsorbed molecules. Since optical properties of molecules are sensitive to the intermolecular interaction with an adsorbent, each orientation state has an individual luminescence spectrum. A change in the equilibrium results in complicated concentration and temperature dependences of the spectra of adsorbed molecules. These dependences have been experimentally observed for several dyes adsorbed on microporous silicate glass. Equilibrium constants and fractal dimensions of the spatial distribution of dye molecules in porous matrices have been determined.