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Updated: Aug 17, 2026

In Situ SIMS and IR Spectroscopy of Well-defined Surfaces Prepared by Soft Landing of Mass-selected Ions
Published on: June 16, 2014
Attenuated partial internal reflection infrared spectroscopy
Zhenfeng Zhang1, George E Ewing
1Department of Chemistry, Indiana University, Bloomington 47405, USA.
Abstract:
A new method for the spectroscopic study of absorbing films is proposed. In contrast to the well-established methods that take advantage of the attenuation of total internal reflection (ATR) to obtain spectra, we intentionally arrange the optics to permit partial internal reflection from the sampling prism face. Attenuated partial internal reflection (APR) spectroscopy is introduced through theoretical calculations and experimental demonstrations. The calculated APR spectra in the infrared region were generated from the Fresnel and Airy equations. Experimentally, APR spectra of water films on a NaCl prism were obtained. APR is more sensitive than ATR, and can easily distinguish water films at the monolayer level (310 pm). The determination of film thickness from interference fringes in APR spectra is also illustrated. It is shown that APR can be used for film thickness measurements that can span 6 orders of magnitude. The limitations of APR are also discussed.
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