title: Recovery of permittivity and depth from near-field data as a step toward infrared nanotomography.
abstract: 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.
authors.affiliation: CIC nanoGUNE, 20018 Donostia-San Sebastián, Spain.
authors.forename: Alexander A
authors.initials: AA
authors.lastname: Govyadinov
authors.forename: Stefan
authors.initials: S
authors.lastname: Mastel
authors.forename: Federico
authors.initials: F
authors.lastname: Golmar
authors.forename: Andrey
authors.initials: A
authors.lastname: Chuvilin
authors.forename: P Scott
authors.initials: PS
authors.lastname: Carney
authors.forename: Rainer
authors.initials: R
authors.lastname: Hillenbrand
mesh_terms: D007259:Infrared Rays; D049329:Nanostructures / Q000737:chemistry; D036103:Nanotechnology / Q000379:methods*; D012822:Silicon Dioxide / Q000737:chemistry; D014054:Tomography / Q000379:methods*
chemical_list: D012822:Silicon Dioxide