X-Ray Diffraction Study of Argon and Xenon in the Liquid State near Their Triple Points

Abstract

X-ray diffraction patterns obtained from liquid argon and liquid xenon in equilibrium with their vapors at temperatures 0.3 K° above their triple points were used to calculate the corresponding distribution functions and radial distribution functions. Isothermal compressibilities and the mean-square variations of the distance between nearest neighbors were calculated from these functions. The numbers of nearest neighbors based on ideal peak fittings were determined to be 8.52 for argon and 8.94 for xenon with peaks occurring in the undamped radial distribution functions at 3.79 and 4.38 Å, respectively. A comparison of the distribution functions for the two liquids indicates that the work is consistent. Distance ratios in the distribution functions are in good agreement with that obtained by Scott et al. for random-packed spheres. Intensity functions of argon were compared with the experimental work of Eisenstein and Gingrich and with the Lennard-Jones convolution-hypernetted-chain (L. J. CHNC) theoretical calculations of Khan. Similar comparisons were made for xenon with the experimental work of Campbell and Hildebrand and with the L. J. CHNC theoretical calculations of Khan and Broyles.