How does this technique compare to optical methods of breaking the diffraction limit such as SNOM (scanning near-field optical microscopy)?
SNOM has shown excellent ability to perform optical measurements below the diffraction limit. To date, SNOM has not been used for spectroscopic measurements over a wide spectral range. Another limitation of the technique is that the light collected in the far field depends on both the real and imaginary index of refraction of the material and sophisticated modeling may be required to extract a spectrum that is analogous to a conventional IR absorption spectrum obtained for example, by FTIR.
