Application of tip-enhanced microscopy for nonlinear Raman spectroscopy

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