FERMI RESONANCES IN THE VIBRATIONAL-SPECTRA OF CSHSEO4 CRYSTALS

A new interpretation of the experimental studies on the vibrational (IR and Raman) spectra of the CsHSeO4 crystal in the region 700-3500 cm-1 is presented and discussed. In this part of the spectra, three regions of Fermi resonance (FR) occur which give rise to the complex bandshape. The well-known trio of bands (A,B,C) is considered as being due to the FR between the fundamental stretching vibration of nu(OH) with the overtone of in-plane bending, 2delta(OH), and the summation tone of gamma(OH) + nu(SeO3) respectively.