Dynamics of molten CF3SO3H·H2O probed by temperature dependent dielectric spectroscopy

Abstract

The complex permittivity of CF3SO3H·H2O was studied in the frequency range 0.3-89 GHz at 298-338 K The microwave spectra which show very broad absorption are analyzed in terms of four Debye processes with relaxation times τ1>τ2>τ3>τ4. Whereas τ2, τ3 and τ4 exhibit Arrhenius behavior at all temps., the relaxation time of the slowest process, τ1, exhibits an unusual temp. dependence which can be fitted by assuming two Arrhenius equations intersecting at ∼315 K At T ≥ 315 K the τ2 process is assigned to rotation of a mixt. of the free acid and its anion. The relaxation time τ3 arises from the reorientation of H2O or H3O+. For both relaxation processes hydrodynamic boundary conditions are close to slip. For the high-frequency process, τ4, the comparison with results from MOPAC calcns. suggests intramol. rotation of the OH-group as the dominating contribution.