Plasmon nanofocusing for the suppression of photodegradation in fluorescence imaging using near-field scanning optical microscopy

Abstract

Near-field scanning optical microscopy (NSOM) is a promising technique to perform nanoscale fluorescence measurements with a nano-sized near-field-light-source. However, much like a conventional confocal measurement, it requires illuminating the sample with the focus spot of the propagating light even when the fluorescence signal of interest is generated only from a nano-sized area of the sample, causing a serious photodegradation of the sample in a large area. Here, we propose to combine NSOM with plasmon nanofocusing to eliminate the direct illumination of the sample by a propagating light and demonstrate that the photodegradation could be significantly suppressed. This approach allows one to perform nanoscale fluorescence imaging with a negligible effect of photodegradation.