Observation of optically inactive phonons for development of a unique near-field spectroscopy method

By combining dedicated near-field generation and detection techniques with Raman spectroscopy, optically inactive phonon activity is predicted. Observation of these phonons opens a new era as a novel analytical technique beyond near-field microscopy/spectroscopy which has previously only been concentrated on obtaining higher spatial resolution. As a possible example of optically inactive phonon observation, measurement of a Raman spectrum of polydiacetylene was demonstrated.