The isotope effect in the electronic structure factors of liquid NH3 and ND3

Gamma rays from a radioisotope source, Am-241, were scattered from samples of liquid light ammonia (NH3) and heavy ammonia (ND3) at temperatures of 294.5 and 284.5 K under their normal vapour pressures to determine the electronic liquid structure factors. In addition the densities of these samples were checked by the gamma ray absorption technique. From the difference between the total electronic structure factors of liquid NH3 and ND3, the difference of the r-space electronic correlation functions of the two liquids (at the same temperature) was evaluated. The observable difference is due (mainly) to quantum effects in the intermolecular electron-density correlation functions of liquid ammonia, which will be discussed.