Practical Aspects of Chemical Studies of Powders by Photoacoustic Spectroscopy

Experience using photoacoustic spectroscopy to study chemical systems such as catalyst powders suggests a number of practical points to be considered in designing equipment and experiments. Cell design, gas atmosphere, temperature, pressure, and the sample are among the factors affecting the sensitivity and quality of spectra. Ultraviolet, visible, and near-infrared spectra have been obtained using a Princeton Applied Research Model 6001 Photoacoustic Spectrometer. For the mid-infrared region a Nicolet Model 7199 Fourier Transform Infrared Spectrometer has been used. Samples studied have included molecules adsorbed on platinum or silver supported on high surface area silica or alumina powders (or pellets), organic and organometallic molecules on silica and alumina powders, polymer foams, coals, oil shale, tissue samples, and others.