Recovery of Permittivity and Depth from Near-Field Data as a Step toward Infrared Nanotomography

• Published in: ACS nano 2014-07, Vol.8 (7), p.6911-6921
• Main Authors: Govyadinov, Alexander A, Mastel, Stefan, Golmar, Federico, Chuvilin, Andrey, Carney, P. Scott, Hillenbrand, Rainer
• Format: Article
• Language: English
• Subjects: Infrared Rays; Nanostructures - chemistry; Nanotechnology - methods; Silicon Dioxide - chemistry; Tomography - methods
• ISSN: 1936-0851; 1936-086X
• DOI: 10.1021/nn5016314

The increasing complexity of composite materials structured on the nanometer scale requires highly sensitive analytical tools for nanoscale chemical identification, ideally in three dimensions. While infrared near-field microscopy provides high chemical sensitivity and nanoscopic spatial resolution in two dimensions, the quantitative extraction of material properties of three-dimensionally structured samples has not been achieved yet. Here we introduce a method to perform rapid recovery of the thickness and permittivity of simple 3D structures (such as thin films and nanostructures) from near-field measurements, and provide its first experimental demonstration. This is accomplished via a novel nonlinear invertible model of the imaging process, taking advantage of the near-field data recorded at multiple harmonics of the oscillation frequency of the near-field probe. Our work enables quantitative nanoscale-resolved optical studies of thin films, coatings, and functionalization layers, as well as the structural analysis of multiphase materials, among others. It represents a major step toward the further goal of near-field nanotomography.