Single molecule localization with four avalanche photodiode detectors

Photoluminescence images can be acquired with detection schemes that have both single-photon sensitivity and nanosecond scale temporal resolution, enabling the study of possible structural bases for photoluminescence lifetimes and other features of the photon arrival statistics. Within the context of super-resolution (SR) imaging, this has been demonstrated with detection schemes that collect images with a bundle of optical fibers that are coupled to individual single-photon counting avalanche photodiode detectors. Recently, our group used a bundle of four optical fibers to collect these "time-resolved photon arrival" images. Despite the paucity of information contained in a four-pixel image, we precisely located the emission centroid of quantum dots (QDs) and observed correlations between centroid location, photoluminescence lifetime, and intensity within clusters of QDs that were suggestive of electronic interactions among them. This proceedings paper details the approach that we used to locate the emission centroid based on the counts in the four detectors.