Tip-Enhanced Near-Field Spectroscopy

Abstract

The synergy of scanning probe microscope and optical microscope realizes a promising sensing technique in surface characterization in the nanoscale with a high chemical sensitivity, which is not attainable by a simple topographic contrast. This paper introduces one of the synergy tools, that is, near-field scanning optical microscope particularly the use of a sharp metallic probe tip. While optical microscope exhibits a high chemical sensitivity, the spatial resolution of conventional optical microscopes using lens is diffraction limited due to wave nature of light. The key technique to break through this limitation is surface plasmon polariton excitation at the tip, which is promising for both high spatial resolution and high sensitivity. This technique has been recently recognized as tip-enhanced near-field spectroscopy.