Fourier-transform infrared photoacoustic spectroscopy of zeolites

Photoacoustic detection is shown to be very valuable for obtaining infrared-spectroscopic data for samples with characteristics that involve very difficult sampling. The modification reactions on the zeolite mordenite, a highly scattering material, are investigated by this technique and by gas-adsorption experiments. The mechanism of the reactions between borane groups inside the channels of the mordenite and amines at different reaction temperatures is described. At low temperatures, amine- and amino-boranes are formed that polymerize at elevated temperatures if steric hindrance is absent. The implantation of boron-nitrogen compounds inside the channels of the mordenite allow a continuous and controlled variation of the accessibility of the mordenite for gas molecules such as krypton and xenon at 273 K.