Photoacoustic Detection of Weak Absorption Bands in Infrared Spectra of Calcite

Photoacoustic spectroscopic detection of infrared absorption often produces spectra with enhanced intensities for weaker peaks, enabling the detection of features due to overtones and combinations, as well as less-abundant isotopic species. To illustrate this phenomenon, we present and discuss photoacoustic infrared spectra of calcite. We use linearization of rapidscan spectra, as well as comparing step-scan and rapid-scan spectra, to demonstrate that saturation is not the driving force behind these enhanced intensities. Our results point to a significant knowledge gap, since a theoretical basis for the enhancement of these weak bands has not yet been developed.

Automated summary

Photoacoustic spectroscopic detection enhances the intensity of weaker peaks, allowing the detection of features due to overtones, combinations, and less-abundant isotopic species. The study demonstrates that saturation is not the driving force behind these enhanced intensities, highlighting a significant knowledge gap in the theoretical basis for the enhancement of weak bands.