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Nanoscale Infrared Spectroscopy: Improving the Spectral Range of the Photothermal Induced Resonance Technique

Published

Author(s)

Aaron M. Katzenmeyer, Vladimir Aksyuk, Andrea Centrone

Abstract

Photothermal Induced Resonance (PTIR) is a new technique which combines the chemical specificity of IR spectroscopy with the lateral resolution of Atomic Force Microscopy. PTIR requires a pulsed tunable laser for sample excitation and an AFM tip to measure the sample expansion induced by light absorption. The limited tunability of commonly available laser sources constrains the application of the PTIR technique to a portion of the IR spectrum. In this work, a broadly tunable pulsed laser relying on a difference frequency generation scheme in a GaSe crystal to emit light tunable from 1.55 µm to 16 µm (from 6450 cm-1 to 625 cm-1) was interfaced with a commercial PTIR instrument. The result is a materials characterization platform capable of chemical imaging, in registry with atomic force images, with a spatial resolution that notably surpasses the light diffraction limit throughout the entire mid-IR spectral range. PTIR nanoscale spectra and images allow the identification of compositionally and optically similar yet distinct materials; organic, inorganic, and composite samples can be studied with this nanoscale analog of infrared spectroscopy, suggesting broad applicability. Additionally, we compare the results obtained with the two tunable lasers, which have different pulse lengths, to address controversy over the mechanism of PTIR signal generation.
Citation
Analytical Chemistry
Volume
85
Issue
4

Keywords

Infrared Spectroscopy, Chemical Imaging, Nanoscale Imaging

Citation

Katzenmeyer, A. , Aksyuk, V. and Centrone, A. (2013), Nanoscale Infrared Spectroscopy: Improving the Spectral Range of the Photothermal Induced Resonance Technique, Analytical Chemistry, [online], https://doi.org/10.1021/ac303620y, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=912932 (Accessed May 26, 2024)

Issues

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Created February 18, 2013, Updated October 12, 2021