Nanoscale chemical analysis by tip-enhanced Raman spectroscopy

A fine metal tip brought to within a few nanometers of a molecular film is found to give strong enhancement of Raman scattered light from the sample. This new principle can be used for molecular analysis with excellent spatial resolution, only limited by the tip apex size and shape. No special sample preparation is required, and the enhancement is identical at every sample location, allowing for quantitative surface-enhanced Raman spectroscopy measurements. When scanning the tip over the sample surface, topographic information is obtained simultaneously and can be directly correlated with the spectroscopic data.