Reorientation of the H2O cage studied by terahertz time-domain spectroscopy

Abstract

The terahertz absorption spectrum of a thin film of liquid H2O of ∼14μm thickness showed a clear absorption mode at 1.56THz(∼53cm−1). This mode is attributed to the bending motion of the intermolecular hydrogen-bond coordinate in a water cage. The dielectric relaxation times of a slow τ1∼9ps and a fast τ2∼0.2ps component (0.4–2.0THz) were determined using a double Debye dielectric model.