Tip-enhanced coherent anti-Stokes Raman nanoscopy

Abstract

Tip-enhanced electric field at a metallic probe tip of apertureless near-field scanning optical microscope (NSOM) was applied to third-order nonlinear optical process, coherent anti-Stokes Raman spectroscopy (CARS). The combination of the enhanced field and third-order nonlinearity successfully resolved molecular vibrations of adenine molecules embedded in DNA double-helix nanocrystals beyond the diffraction limit of light.