Photo-induced Force Microscopy: Nanoscale Imaging With Chemical Recognition

Photo-induced Force Microscopy (PiFM) enables spectroscopic probing of materials with nanoscale spatial resolution (< 10 nm). Advances in nanotechnology have intensified the need for tools that can characterize newly synthesized nano-materials. Combining scanned-probe techniques with optical illumination provides nanoscopic spatial resolution through the sharp tip (~10 nm) with the chemical recognition provided by optical spectroscopy. PiFM is a new and powerful technique which enables spectroscopic probing of nano-materials with a spatial resolution under 10 nm and broadband spectral sensitivity (optical through IR). In PiFM, the response of the optically excited sample is probed directly in the near-field by reading out the time-integrated force between the tip and the sample. Because the magnitude of the force is dependent on the photo-induced polarizability of the sample, PiFM exhibits spectroscopic sensitivity. With very high spatial resolution even under ambient conditions, PiFM enables the real-space imaging along with chemical recognition of a wide range of nano-materials, from semiconducting nanoparticles to polymer thin films to sensitive measurements of single molecules. The principles and the basic components of the PiFM will be presented with examples that highlight the nanoscale imaging and spectroscopic sensitivity inherent to the technique. Recent samples investigated with PiFM will be presented, including: polymer blends, nano-fibers, polypeptides, block copolymers, and 2D materials.
Ryan Murdick (Molecular Vista)