Application of the Shifting Method as a Technique to Correct for the Background in Quantitative Analysis by Open-Path FTIR.

In open-path Fourier Transform Infrared spectroscopy, the generation of a suitable background single-beam spectrum is of major concern. The Shifting Method is a derivative-like approach to correct for the background without the need to actually measure a background spectrum using the sample single-beam spectrum. A thorough study of the Shifting Method was conducted. A set of guidelines was developed based on the results of artificial and closed cell data. These guidelines were applied to three different data sets, consisting of cell and open path data with multiple compounds, overlapping peaks, and high water vapor and aerosol levels.