EXPRESS: Understanding Advanced Attenuated Total Reflection Correction: The Low Absorbance Assumption

We present an attenuated total reflection (ATR) correction scheme capable of rectifying ATR spectra while considering the polarization state for arbitrary angles of incidence, provided that this angle exceeds the critical angle for the entire ATR spectrum. Due to its reliance on the weak absorption approximation, it cannot achieve perfect correction of the ATR spectra. However, comprehending its functionality may offer valuable insights into the concept behind the weak absorption approximation. Depending on the specific polarization state of an instrument accessory combination, this correction scheme may outperform the proprietary advanced ATR correction authored by ThermoFisher while being as user-friendly, but in contrast to the latter completely transparent with regard to its functionality.