Correlation spectroscopy of individual molecules immobilized on surfaces under ambient conditions

Individual dye molecules, immobilized on surfaces have been observed under ambient conditions with confocal microscopy. The temporal evolution of the fluorescence intensity of these molecules is studied via the autocorrelation function of the fluorescence intensity. Nonexponentially decaying correlation functions with time constants ranging from 50 ms to 5 s have been observed for different molecules. A statistical analysis on 40 different molecules yields typical correlation times around 100 ms and 6 s.