Nondestructive multimodal chemical, mechanical measurement of materials with sub 10 nm spatial resolution together with topography provide correlative information of on heterogeneous materials and nature samples. However, such multimodal nanoscale chemical and mechanical correlations are difficult to achieve, due to the diffraction limit of optical microscopy and constraints from instrumental complexities. Here, we present peak force infrared (PFIR) microscopy, a multimodal non-invasive spectroscopic scanning probe microscopy. PFIR microscopy allows chemical sensitive imaging through mapping the infrared absorption through laser-induced thermal expansions, and simultaneous acquisition of modulus and adhesion through the peak force tapping. Both functionalities are obtained with sub 10 nm spatial resolution. We demonstrate that PFIR microscopy is capable of measuring both soft organic materials and rigid inorganic materials. As an action-based microscopy, the principle of PFIR also applies to other frequency range.<br/><br/>As a demonstration, the nanophase separation of a di-block copolymer of PS-b-PMMA was measured at characteristic infrared frequencies to reveal the distribution of constituent domains (see attached figure). As high as 6 nm spatial resolution in the chemical sensitive imaging was demonstrated from the infrared imaging capability of PFIR the microscopy. This spatial resolution, in fact, surpasses many nanoscale infrared microscopy. PFIR microscopy allows us to measure the nanoscale spectroscopic responses of amyloid fibrils, bypassing the spatial inhomogeneous broadening. We also demonstrated the nanoscale measurement on urban aerosol particles to access nanoscale inhomogeneity within individual particles. The high spatial resolution and high sensitivity enable PFIR microscopy to be a powerful analytical tool for nanoscale exploration.

Peakforce infrared microscopy: Non-invasive correlative infrared and mechanical imaging at sub 10nm spatial resolution

256th National Meeting (2018)

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