Chemical Imaging Beyond the Diffraction Limit: Experimental Validation of the PTIR Technique

Photothermal induced resonance (PTIR) has recently attracted great interest for enabling chemical identification and imaging with nanoscale resolution. In this work, electron beam nanopatterned polymer samples are fabricated directly on 3D zinc selenide prisms and used to experimentally evaluate the...

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Bibliographic Details
Published in:Small (Weinheim an der Bergstrasse, Germany) Germany), 2013-02, Vol.9 (3), p.439-445
Main Authors: Lahiri, Basudev, Holland, Glenn, Centrone, Andrea
Format: Article
Language:English
Subjects:
AFM
Analytical chemistry
Atomic force microscopy
Chemical analysis
chemical imaging
Diffraction
electron beam lithography
Imaging
infrared spectroscopy
Linearity
Nanocomposites
Nanomaterials
nanoscale characterization
Nanostructure
Nanotechnology
Studies
Three dimensional
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Summary:Photothermal induced resonance (PTIR) has recently attracted great interest for enabling chemical identification and imaging with nanoscale resolution. In this work, electron beam nanopatterned polymer samples are fabricated directly on 3D zinc selenide prisms and used to experimentally evaluate the PTIR lateral resolution, sensitivity and linearity. It is shown that PTIR lateral resolution for chemical imaging is comparable to the lateral resolution obtained in the atomic force microscopy height images, up to the smallest feature measured (100 nm). Spectra and chemical maps are produced from the thinnest sample analyzed (40 nm). More importantly, experiments show for the first time that the PTIR signal increases linearly with thickness for samples up to ≈ 1 μm (linearity limit); a necessary requirement towards the use of the PTIR technique for quantitative chemical analysis at the nanoscale. Finally, the analysis of thicker samples provides the first evidence that the previously developed PTIR signal generation theory is correct. It is believed that the findings of this work will foster nanotechnology development in disparate applications by proving the basis for quantitative chemical analysis with nanoscale resolution. Quantitative chemical imaging with nanoscale resolution is demonstrated using a photothermal induced resonance technique by measuring the sample thermal expansion induced by the absorption of IR light with an atomic force microscopy tip. Lateral resolution, sensitivity, and linearity of the technique is evaluated with lithographically defined samples.
ISSN:1613-6810
1613-6829
DOI:10.1002/smll.201200788