Overcoming the Contact Problem in Quantitative Attenuated Total Reflection Spectroscopy Analysis of Flat Samples

Area of Science:

• Spectroscopy
• Optical Physics
• Materials Science

Background:

• Attenuated total reflection (ATR) spectroscopy is a powerful technique for analyzing material optical properties.
• Accurate measurement of optical functions can be challenging when there is poor contact between the sample and the internal reflection element.
• Existing methods may struggle to provide reliable results under suboptimal contact conditions.

Purpose of the Study:

• To develop a robust method for measuring optical functions of homogeneous, isotropic materials using ATR spectroscopy.
• To address the challenge of poor sample-internal reflection element contact in ATR measurements.
• To enable accurate determination of optical properties even when the gap distance is unknown.

Main Methods:

• The proposed method involves treating the spacing between the internal reflection element and the sample as an adjustable parameter.
• Simultaneous fitting of s- and p-polarized spectra is performed, incorporating the unknown gap distance into the model.
• The approach utilizes dispersion model parameters alongside the spacing parameter for comprehensive analysis.

Main Results:

• The method was successfully tested using both synthetic and experimental (polystyrene) spectra.
• Accurate determination of optical functions was achieved despite the presence of a contact problem.
• The results validate the effectiveness of treating sample spacing as a variable parameter.

Conclusions:

• The developed method provides a reliable way to measure optical functions via ATR spectroscopy, even with imperfect sample contact.
• This technique enhances the applicability of ATR spectroscopy in scenarios with suboptimal experimental conditions.
• The ability to determine optical functions accurately in the presence of a contact problem offers significant advantages for material characterization.