A Simplified, Effective ATR Correction Method for Spectral Identification

Poor Man’s ATR Correction (PMATRC) uses a ratio of the spectral absorbance to its Kramers-Kronig transform. Unlike more sophisticated correction methods, PMATRC does not require information about the angle of incidence, the refractive index function of the ATR crystal, or the refractive index of the sample in the transparency region between the mid-infrared and visible spectral regions. Using 10 compounds, different ZnSe crystals, a Ge crystal, and polarizers, we demonstrate that PMATRC is almost always capable of increasing the Pearson correlation to a value high enough for compound identification based on a database containing true absorbance data. These high correlation values are primarily achieved by correcting the peak positions, although peak intensities may only be accurate for peaks that adhere to the low absorption condition typically applied in ATR spectroscopy.