ROTATIONAL DIFFUSION PARAMETERS OF CYANINE DYES DETERMINED BY DEPOLARIZATION OF LUMINESCENCE

The polarization anisotropy of the luminescence of several cyanine dye s in solution were measured under CW laser excitation as a function of the temperature. The iodide salt of diethyloxacarbocyanine (DOCI), di ethyloxadicarbocyanine (DODCI), diethylthiacarbocyanine (DTCI) and die thylthiadicarbocyanine (DTDCI) have been studied in ethanol. Experimen tal results were interpreted in terms of asymmetric rotor models, in o rder to find out the effective molecular volume in solution and to dec ide between two hydrodynamic boundary conditions (stick-slip).