Detection and Signal Processing for Near-Field Nanoscale Fourier Transform Infrared Spectroscopy
Abstract
Researchers from a broad spectrum of scientific and engineering disciplines are increasingly using near-field infrared spectroscopic techniques to characterize materials nondestructively and with nanoscale spatial resolution. However, sub-optimal understanding of a technique's implementation can complicate data interpretation and even act as a barrier to enter the field. Here we outline the key detection and processing steps involved in producing scattering-type near-field nanoscale Fourier transform infrared spectra (nano-FTIR). The largely self-contained work (i) explains how normalized complex-valued nano-FTIR spectra are generated, (ii) rationalizes how the real and imaginary components of spectra relate to dispersion and absorption respectively, (iii) derives a new and generally valid equation for spectra which can be used as a springboard for additional modeling of the scattering processes, and (iv) provides an algebraic expression that can be used to extract the sample's local extinction coefficient from nano-FTIR. The algebraic expression is validated with nano-FTIR and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectra on samples of polystyrene and Kapton.
- Publication:
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arXiv e-prints
- Pub Date:
- March 2023
- DOI:
- 10.48550/arXiv.2303.10329
- arXiv:
- arXiv:2303.10329
- Bibcode:
- 2023arXiv230310329L
- Keywords:
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- Physics - Optics;
- Condensed Matter - Materials Science;
- Physics - Applied Physics
- E-Print:
- 44 pages, 9 figures, supplemental material spans the last 15 pages of the pdf file