Etude, par Spectroscopie de Vibration Infrarouge et Raman, du Dihydrate de l'Acide Perchlorique dans les Etats Désordonnés: Verre et Liquide

The infrared and Raman spectra of the mixture HClO 4 · 2H 2 O in the glassy and liquid states have been investigated. Two species have been characterized: (a) the dioxonium perehlorate where the H 5 O 2 + and ClO 4 − ions are linked by hydrogen bonds weaker than in the crystal (ν OH (H 5 O 2 + ) = 3430 and 3460 cm −1 respectively in the glass and liquid state Raman spectra and 3340 cm −1 for the crystal). (b) an ionic association, O 3 ClO − …H(OH)HOH 2 + , in which the vibrational motions of the terminal H 2 O molecules are characterized by δ OH = 1530 and 1550 cm −1 and ν OH = 3480 and 3520 cm −1 respectively in the glass and liquid state Raman spectra and in which ν 1 (ClO 4 − ) shifts to lower frequencies (Δν = −12cm −1 ).