Anharmonic effects on the OH stretching vibrations of the Na5H3(SeO4)(4).2H(2)O crystal

Polarized infrared spectra of pentasodium trihydrogen tetraselenate dihydra te, Na5H3(SeO4)(4). 2H(2)O, are analysed using a model which takes account of the Fermi resonance interactions between the OH stretching vibrations an d various combination tones. It is demonstrated that the short, centrosymme tric, hydrogen bond of the hydrogendiselenate anion generates an intense br oad absorption whose spectral features can be described taking into conside ration strong interaction between tile nu (a)(OHO) stretching vibration and lattice phonons, while the longer hydrogen bond linking hydrogenselenate i ons to tile hydrogendiselenate anion gives a typical ABC band structure.