Abstract
Infrared refractive indices of organic materials are typically resolved through IR ellipsometry. This technique takes advantage of optical interference effects to solve the optical constants. These are the same effects that complicate the analysis of coherent spectroscopy experiments on thin films. Vibrational sum frequency generation is an interface-specific coherent spectroscopy that requires spectral modeling to account for optical interference effects to uncover interfacial molecular responses. Here, we explore the possibility of leveraging incident beam geometries and sample thicknesses to simultaneously obtain the molecular responses and refractive indices. Globally fitting a higher number of spectra with a single set of refractive indices increases the fidelity of the fitted parameters. Finally, we test our method on samples with a range of thicknesses and compare the results to those obtained by IR ellipsometry.
| Original language | English (US) |
|---|---|
| Article number | 110901 |
| Journal | Journal of Chemical Physics |
| Volume | 156 |
| Issue number | 11 |
| DOIs | |
| State | Published - Mar 21 2022 |
Bibliographical note
Funding Information:The authors gratefully acknowledge partial support from the National Science Foundation under Grant No. DMR-1611047. T.A.D. thanks J. A. Woolam for discussion of common usage line shapes in IR-VASE. Part of this work was conducted in the Minnesota Nano Center, which is supported by the National Science Foundation through the National Nanotechnology Coordinated Infrastructure (NNCI) under Award No. ECCS-2025124.
Publisher Copyright:
© 2022 Author(s).
PubMed: MeSH publication types
- Journal Article