Probing strong adsorption of individual solute molecules at solid/liquid interfaces with model-based statistical two-dimensional correlation analysis

Single-molecule spectroscopy is a powerful approach to studying adsorption phenomena at solid/liquid interfaces that are responsible for peak tailing in chromatography. For complete understanding of adsorption properties, a statistically significant number of strong adsorption events of single molecules need to be identified and their corresponding desorption times be determined. In this paper, model-based statistical two-dimensional (2D) correlation analysis is used to search/identify individual strong adsorption events from large data sets of single-molecule photon bursts. It is accomplished by correlating the single molecule photon-burst data with a model adsorption function. The desorption times are evaluated by varying the model size and moving the model function along time axis in 2D correlation analysis. It is shown that 2D correlation analysis can reliably determine strong adsorption events where many other molecules are diffusing through the laser probe volume during the adsorption of one molecule, and/or the adsorbed molecule experiences complex photophysical behaviors such as triplet blinking and spectral diffusion.