Association Moléculaire et Paire Ionique dans le Verre et le Liquide du ‘Monohydrate de l'Acide Nitrique’

The Raman spectra of the equimolecular mixture HNO3·H2O in the liquid and glassy states have been investigated in the range 4000–50 cm−1. At least four species have been characterized: (i) The free molecular association H2O…HONO2 νOH(H2O) = 3550 cm−1 (3440 cm−1) and νOH(HNO3) = 2930 cm−1 (2915 cm−1) respectively in the liquid (and the glass). (ii) The free ionic pair (H2OH)+…(ONO2)− that give a splitting (Δν = 170 cm−1) of the ν3(NO) vibration. (iii) Free HNO3 molecules: νNOH = 940 and 950 cm−1 respectively in the liquid and the glass. (iv) The ‘nitric acid trihydrate’: H7ONOνOH between 3100 and 3300 cm−1.