Scanning Raman Picoscopy: Ångström-Resolved Tip-Enhanced Raman Spectromicroscopy^†

In this review, we present a brief overview on the recent advances in Ångström-resolved tip-enhanced Raman spectromicroscopy. We first introduce the theoretical understanding of the confinement of light at the atomistic scale, and explain how the Raman scattering from a single molecule happens under the "illumination" of such an atomically confined light. Then we describe the latest developments on Ångström-resolved tip-enhanced Raman spectromicroscopy, particularly on a new methodology called "scanning Raman picoscopy" for visually constructing the chemical structure of a single molecule in real space. Finally, we give a perspective of this technique in various applications where identifying the chemical structures of materials at the chemical bond level is required.