Near-infrared excited Fourier transform Raman spectroscopy, using pyri
dine as a probe molecule provides both qualitative and quantitative in
formation on zeolite surfaces. However, sensitivity and heating proble
ms may occur. Notwithstanding these limitations, very small changes ca
n be monitored in the adsorption strength of different sites on zeolit
e surfaces, caused by traces of water. Adsorption on different (acidic
) sites affects the symmetry of the adsorption complex, and hence resu
lts in varying appearances of the vibrational modes in the spectra.