Compton scattering evidence for covalency of the hydrogen bond in ice

Periodic intensity variations in the measured Compton profile anisotropies of ordinary ice Ih correspond to distances of 1.8 and 3.0 Angstrom, which are close to the hydrogen bond length and the nearest-neighbor O-O distance, respectively. We interpret this result as direct evidence for the covalent nature of the hydrogen bond. Very good quantitative agreement between the data and a fully quantum mechanical bonding model for ice I-h, and the disagreement with a purely electrostatic (classical) bonding model support this interpretation and demonstrates how exquisitely sensitive Compton scattering is to the phase of the electronic wavefunction. (C) 2000 Published by Elsevier Science Ltd. Ail rights reserved.