A Systematic Analysis of Microstructured Silicon ATR-FTIR Reflection Elements: Operating Parameters, Performance and Underlying Phenomena

Microstructured silicon internal reflection elements (μSi-IREs) have the potential to revolutionize attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy. This study compares the analytical performance of leading μSi-IREs from three prominent providers, examining the influence of ridge angle and sensor footprint on key figures of merit. All μSi-IREs delivered high-quality spectra and calibration curves, enabling quantitative concentration measurements and spectral line shape analysis. μSi-IREs with a 35 degree ridge angle and large sensor area exhibited sensitivities approaching 10−4 mM−1 and detection limits as low as 0.3 mM, outperforming smaller μSi-IREs with a 55 degree ridge angle. Theoretical analysis investigated the effects of beam alignment and revealed fundamental structure-performance relationships, providing design guidelines for next-generation spectroscopic systems. The analysis was benchmarked against a commercial diamond ATR accessory. The inherent advantages of μSi-IREs-including low cost, ease of use, and system integrability-combined with this rigorous performance evaluation, position these microstructured ATR components for novel and impactful applications in analytical spectroscopy.