Self-interference fluorescent emission microscopy 5-nm vertical resolution

Summary form only given. We present a new method of fluorescence imaging, which yields an unprecedented vertical resolution. The basic principles are related to an already well-established technique of using spatially modulated emission intensity from standing waves. However, instead of spatial variation, our method uses the unique spectral signature of the fluorescent emission intensity above a reflecting surface to determine vertical position unambiguously. We demonstrate better than 5-nm vertical resolution by clearly distinguishing markers bound directly to the substrate from those bound on top of a single layer of streptavidin. Applications of this technique include intracellular imaging and screening for specific bacteria, virus or proteins, where, discrimination between raised fluorescently labeled specifically bound markers from non-specific binding is crucial.