Direction-resolved nanoscale optical imaging with near-nanometer resolution by emerging infrared torsional force microscopy (opens in new tab)

Resolving nanoscale light-matter interactions requires both high spatial resolution and anisotropic sensitivity to in-plane and out-of-plane optical responses. We introduce torsional force microscopy-infrared microscopy, a new optical imaging technique that combines cantilever torsional dynamics with a nonlinear frequency-mixing scheme to map both in-plane and out-of-plane photothermal signals. Using birefringent mica as a model system, we resolve distinct in-plane and out-of-plane vibrationa...