Infrared correlation nanoscopy with unprecedented spectral coverage

Nanoscale resolved imaging and spectroscopy utilizing scattering-type Scanning Near-field Optical Microscopy (s-SNOM) or tapping AFM-IR (local detection of photothermal expansion) bypass the ubiquitous diffraction limit of light and achieve a spatial resolution less than 20 nm in the Infrared (IR) spectral range. Measurements have successfully demonstrated a wide range of analytical capabilities such as nanoscale chemical mapping and material identification, conductivity profiling and electric field mapping. The employed laser source critically determines the range of materials and phenomena which can be studied, motivating to continuously explore options to expand the accessible range, especially towards longer IR wavelengths. Here, we introduce a new tunable OPO laser source optimized for IR nanoscopy applications which covers a spectral range of 2-18 μm. To illustrate the capabilities of this laser source, we demonstrate correlative s-SNOM and tapping AFM-IR+ based imaging, point spectroscopy and hyperspectral imaging. Application examples for investigating phonon polaritons in hBN and MoO3 and determining the nanoscale chemical composition of a thin film polymer blend.