Scanning probe Raman spectroscopy with single molecule sensitivity
|Reviews and Highlights||Quantum Science||Molecular and Soft-matter||Ultrafast Nano-optics and Nanophotonics||Mineralogy and Geochemistry|
Single-molecule vibrational Raman spectroscopy of malachite green adsorbed on planar metal surfaces is achieved by means of optical local-field enhancement provided by a scanning nanoscopic metallic tip. The single-molecule signature is evident from spectral diffusion and a discretization of Raman peak intensities. The optical tip-sample coupling gives rise to a localization of the response down to a sub-10 nm length scale and a Raman enhancement up to ∼5 Ã— 109. This combines vibrational spectroscopy with high resolution scanningprobe microscopy for ultrasensitive in situ analysis of individual molecules.