PSF Distortion in Dye–Plasmonic Nanomaterial Interactions: Friend or Foe?

Plasmonic nanostructures offer promising applications as nanocatalysts, but optimizing their structure–function relationship using optical superlocalization techniques is hindered by the formation of distorted point spread functions (PSFs). Previously reported localization bias for remotely excited Alexa-647 adsorbed to Ag nanowires is investigated here for its potential to provide useful information about surface interactions. Two main classes of abnormal PSFs are examined: single-lobed PSFs, in which the localization bias arises from various emitter positions around the nanowire, and bilobed PSFs arising from emitters near the top edge of the nanowire. The amount of localization bias for these two populations diverges for ground truth widths less than 300 nm and suggests the latter adsorption and resulting orientation arise more frequently under experimental conditions than is predicted by simulation. Nanowires with widths in the range of 200 to 300 nm are found to have the greatest potential for distinguishing between single-lobed and bilobed PSFs in experiment. Finally, we present a fitting method for abnormal PSFs using a basis of Hermite–Gaussian functions and show that orientation information is encoded in bilobed PSFs