Two-Color Correlation Spectroscopy

摘要

For successful SMD, stable fluorophores are necessary. No clear distinction whether OPE or TPE are more suitable with respect to in-vivo SMD is possible. The photophysics of the dyes are still crucial since they decide about its usability. We show that simultaneous two color experiments are a new approach helpful for the investigation of many photophysical processes. The elucidation of the bleaching mechanism in TPE is simplified due to decoupling of the excitation process and the bleaching process by two-color irradiation. In the case of GFP, one color populates a dark state while the second color is used for the characterisation of a dark state. This latter example clearly shows the potential of these techniques since it allows the enhancement of the brightness of individual GFP molecules. The still unsolved problem of the limited photostability might be overcome by means of CARS-spectroscopy. Although a third order non-linear optical process, the experimental setup resembles that of a two-color experiment. The high sensitivity of CARS can be exploited for microscopy as for the combination of CARS with correlation spectroscopy.