Abstract
Inelastic x-ray scattering data from water at show a variation of the velocity of sound from 2000 to 3200 in the momentum transfer range . The transition occurs when, at , the energy of the sound excitations equals that of a second weakly dispersing mode. This mode is reminiscent of a phonon branch in ice crystals, which is shown here to be of optical transverse character. The present work accounts for most of the highly debated difference between hydrodynamic and high-frequency velocities of sound in water.
- Received 1 April 1996
DOI:https://doi.org/10.1103/PhysRevLett.77.83
©1996 American Physical Society