Molecular Relaxation of Binary Systems LiNO3–LiClO4, NaNO3–NaNO2, K2CO3–K2SO4

Abstract

Molecular relaxation in binary systems LiNO₃–LIClO₄, NaNO₃–NaNO₂, and K₂CO₃–K₂SO₄ is studied using Raman spectroscopy. The relaxation time of ν₁(A) vibrations for NO₃⁻ and CO₃²⁻ anions is found to be shorter in LiNO₃–LIClO₄, NaNO₃–NaNO₂, K₂CO₃–K₂SO₄ than in LiNO₃, NaNO₃, K₂CO₃, respectively. Higher relaxation rate is explained by additional relaxation of excited vibrational states. This mechanism is associated with vibrational excitation of the second anion ( ClO₄⁻, NO₂⁻, SO₄²⁻ ) and “production” of a lattice phonon. This relaxation mechanism is possible when the difference between the frequencies of these vibrations falls into the region of fairly high density of states of the phonon spectrum.