Abbe’s diffraction limit prevents straightforwardly resolving the micro/nanoscale heterogeneous materials with mid infrared light. In this presentation, I will describe our invention on peak force infrared (PFIR) microscopy . The PFIR microscopy utilizes temporal domain mechanical detection of the tip-enhanced infrared photothermal response of the sample with a nanoscopic atomic force microscope (AFM) tip. The PFIR works in both air phase and liquid phase. We have demonstrated the imaging capability of PFIR on a wide range of materials from block copolymer, amyloid fibril, cellular structures to secondary organic aerosols, oil shale source rock, and two-dimensional polaritonic materials. A spatial resolution of 6 nm is demonstrated across different types of samples. In addition, we have integrated the PFIR microscopy with other modalities of chemical measurement and imaging, including mechanical property measurement and surface potential mapping.
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