Detection of Fluorescence from Single Chlorophyll a Molecules Absorbed on Glass Surface

We investigate the single molecule spectroscopy of chlorophyll a molecules on glass surface in N₂-saturated environment. The basic photodynamic parameters of chlorophyll a molecules, such as fluorescence lifetime, survival time before photobleaching, on-time, and off-time, are reported. A four-level model is employed to describe the possible dynamics and photobleaching of chlorophyll a upon excitation. Broad distributions in fluorescence lifetimes and survival times are mainly due to the heterogeneities of both molecular conformation and local environment.