TIME-RESOLVED SINGLE-MOLECULE SPECTROSCOPY

A new method based on the calculation of autocorrelation functions for spectra measured at a high acquisition rate is developed to study spe ctral dynamics of single molecules. The technique allows for spectrosc opy with time resolutions down to the luminescence lifetime. The metho d is used to study spectral diffusion in two-photon excitation spectra of diphenyloctatetraene molecules doped in an n-tetradecane crystal m atrix. The diffusion is light induced, and is absent in one-photon exc itation spectra. It has a ''steplike'' time behavior, different from g radual diffusion observed in glasses.