The structure of hydrogen chloride gas

Abstract

A new experiment to measure the intermolecular partial structure factors for hydrogen chloride gas (e.g. H-H structure factor, etc.) at a temperature of 355·7 K and density 0·29 × 10²⁸ molecules m^-3, by neutron diffraction and isotopic substitution, is described. Data with good counting statistics and corrected for many side effects are required. Observed scattering patterns are complicated by the large, incoherent, energy and angle-dependent, single molecule scattering function. This function is shown to be independent of density to about 5 per cent for the gas densities, and can be simulated to good accuracy by a calculation based on an ideal gas of quantum rotators. Partial structure factors obtained in this experiment provide a standard on which to test models of the intermolecular potential.