Comparison of photoacoustic and attenuated total reflectance for the qualitative analysis of a bituminous Colombian coal by Fourier transform infrared spectroscopy

Abstract

A Colombian coal from La Loma, Cesar, Colombia, field was characterized by Fourier transform infrared photoacoustic spectroscopy. Spectral analysis was focused on the mid-infrared, where previous publications have shown remarkable changes in the coal structure. Instrumental parameters of the infrared spectrometer were investigated for optimal spectra acquisition. Optimal parameters are a mirror velocity of 0.16 cm/s, a number of scans of 512, and a resolution of 2 cm-1. Results of Fourier transform infrared photoacoustic spectroscopy were compared with Fourier transform infrared attenuated total reflectance for validation. Both techniques can be implemented with a minimum sample preparation. Finally, vibrational modes of the functional groups were identified.