Effect of Overlapping Bands on Intensities in ATR FT-IR Spectra

In this study, several spectra were simulated, and the effect of spectral resolution and intensity is compared for ATR and transmission measurements. The analysis of ATR spectra shows that the intensity differences become more pronounced with the increasing band intensities and decreasing separation of the bands. The intensity ratio differences in ATR spectra are due to the superposition of the asymmetric dispersion bands of the refractive index spectrum. The difference between the spectral features in an overlapping region in ATR and transmission measurements is illustrated, and it is shown that the optical dispersion effect can be effectively eliminated by converting an ATR spectrum into its absorbance counterpart with the use of the Kramers-Kronig transform.