THE INTERATOMIC STRUCTURE OF ARGON IN WATER

The first order difference method of neutron diffraction and isotopic substitution has been applied to argon dissolved under pressure in hea vy water. The results show that argon atoms possess a well-defined nea rest neighbor hydration shell composed of 16(2) water molecules in the range 2.8 less than or equal to r (Angstrom) less than or equal to 5. 4. Also evident is a weaker second shell which extends to: similar to 8 Angstrom. The results are in broad agreement with those obtained fro m Monte Carlo and M.D. computer simulation of models in which an argon atom interacts with a number of water molecules via pairwise additive forces. Significant differences are discernible when attempts are mad e to match quantitatively the theoretical results over the entire rang e of the experimental information.