Vibrational Ground-State depletion for enhanced resolution sum frequency generation microscopy

The study of surfaces, which provides unique information on chemical and physical properties, has led to the development of specialized tools including Sum Frequency Generation (SFG) spectroscopy. To map the chemical heterogeneity across the surface plane, the SFG spectroscopic imaging has been developed. SFG imaging has proven to be a useful tool for studying surface specific species through their vibrational signatures. However, the effective resolution of the imaging is limited to micrometer length scales often by the diffraction limit of the midIR wavelengths deployed in vibrationally sensitive SFG imaging. Therefore, many interesting sub-micron features are out of reach for such imaging techniques. This article introduces a technique to achieve super-resolution using ground state depletion from a structured area around the focal-spot of a raster-scan imaging scheme. The proof-of-concept results are presented using hydrogen terminated silicon (Si(1 1 1)) as sample surface with results indicating a 3-fold resolution improvement.

Automated summary

The study of surfaces provides unique information on chemical and physical properties, leading to the development of specialized tools such as SFG spectroscopy. However, the resolution of SFG imaging is often limited to micrometer length scales, making it unable to capture sub-micron features. This article introduces a technique using ground state depletion to achieve super-resolution, with proof-of-concept results showing a 3-fold improvement in resolution.