WATER ABOVE ITS BOILING-POINT - STUDY OF THE TEMPERATURE AND DENSITY-DEPENDENCE OF THE PARTIAL PAIR CORRELATION-FUNCTIONS .1. NEUTRON-DIFFRACTION EXPERIMENT

Neutron diffraction data on water, employing the technique of hydrogen /deuterium isotope substitution, are reported at three thermodynamic s tates above the boiling point. The structural information is analyzed in terms of the partial radial distribution functions, OO, OH, and HH, which are extracted from the neutron data. It is found that temperatu re affects mainly the medium and longer range order in the liquid, whi le density plays a significant role in controlling the degree of hydro gen bonding. To understand the structure of water obtained from these data it appears that many-body cooperative interactions have to be cor rectly accounted for.