High-pressure x-ray diffraction measurements for supercritical fluid oxygen at 0.9, 1.2, 4.3, and 5.2 GPa and for supercritical fluid nitrogen at 2.5 GPa have been carried out at room temperature by using synchrotron x-ray diffraction. The structure factors have been interpreted by means of the reverse Monte Carlo method. Site-site and center-center radial distribution functions and relative orientations of molecular axes as a function of distance between molecular centers have been calculated from the particle configurations. At distances below the position of the first maximum of the center-center radial distribution function, the dominance of parallel and "X-shaped" alignments of neighboring molecules has been revealed. Superfluid O2 was found to display considerably stronger orientational correlations than N2. Structural differences between oxygen at 4.3 and 1.2 GPa can be explained by the different densities of these systems.
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - Jul 29 2008|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics