The relation between structure and vibrational spectra of natural zeolites

In this paper, the vibrational (IR and Raman) spectra of natural zeolites, belonging to six structural groups are presented. The band characteristics of the middle range order occur in the spectral region of 400-800 cm-1. In this range bands due to the vibrations of different rings of alumino- and silicooxygen tetrahedra, creating the secondary building units, are located. Increase in the number of ring members results in the shift of the characteristic band position towards lower wavenumbers in the IR spectra. Such a tendency is not so evident in the Raman spectra. It has been proved that vibrational spectra are useful for the identification of a majority of zeolite structural groups, though unequivocal assignment of pseudolattice bands is difficult.