AFMIR signal map at 1600 cm⁻¹ of the region of interest “A” and overlaid selected positions (1–9) with full spectra surrounding the image. The far-field spectrum is shown in the same wavenumber range. The white isocontour delineates the height corresponding to 15% of the maximum height measured by the AFM tip. It delineates the AFM sample boundaries and outlines the overall particle shape.