Compensation of electrostatically-induced background in s-SNOM.

Scattering-type Scanning Near-field Optical Microscopy (s-SNOM) and nano-FTIR are modern techniques for nanoscale imaging and spectroscopy across Visible, IR and THz regions with wavelength-independent spatial resolution <20 nm. s-SNOM is based on the atomic force microscopy (AFM), where a sharp AFM tip is illuminated by focused light beam. The tip acts as an antenna that receives the incoming light and channels it into a strong nanoscale hotspot at its apex. The near-field interaction of this hotspot with the sample directly below the tip modifies the tip scattering properties. We pioneered technologies for background-free detection for this tip scattering, providing means for reliable nanoscale analysis. However, here we show that despite advanced background suppression techniques, scattering SNOM could be a subject for traditional AFM-related artefact related to electrostatic influences. 

We further introduce Electrostatics-compensated s-SNOM in order to compensate undesirable electrostatic interaction, enabling in-situ probing of local electric potentials along with the pristine optical responses and topography of the sample surface. Validity of this method of artefact suppression was demonstrated on metals, dielectrics and ferroelectrics.