Quantum effects in the structure of water measured by gamma ray diffraction

Abstract

Gamma rays from a radioisotope source, 241Am, are scattered from samples of light water (H 2O) and heavy water (D 2O) at temperature 297 K and density 0.0334 molecules/Å 3 to determine what differences occur in their structure factors. The apparatus, method of data collection and data analysis are described in detail. The results are compared to the predictions of a computer simulation, in which ground state librational motion of rigid molecules causes significant quantum effects in the site-site correlation functions of the two liquids. Differences between our data and the simulation suggest that coupling occurs between intramolecular and intermolecular modes, and influences the structure of water. It is noted that the structural changes due to quantum effects are similar to those that occur in water upon formation of a 0.55 M solution of LiOH.