Optical near-field Raman imaging with subdiffraction resolution

We report optical near-field Raman imaging with subdiffraction resolution (similar to120 nm) without field enhancement effects. Chemical discrimination on tetracyanoquinodimethane organic thin films showing localized salt complexes is accomplished by detailed Raman maps. Acquisition times that are much shorter than previously reported are due to the high Raman efficiency of the materials and to a careful collection and detection of the optical signals in our near-field Raman spectrometer.