Single molecule spectral dynamics at room temperature

Sequences of single-molecule fluorescence spectra are presented with integr ation times per spectrum as short as 25 ms. By reducing averaging effects i n the time domain, the vibronic bands appear better resolved, often they sh ow distinct bands instead of a shoulder in time-averaged spectra. Furthermo re, we note that the fluctuation of the intensity ratio of the vibronic ban ds can considerably contribute to room-temperature spectral diffusion. This is in contrast to spectral diffusion of narrow homogenous Lorentzian absor ption line profiles at cryogenic temperatures. (C) 2000 Elsevier Science B. V. All rights reserved.