XAS of high pressure Xe clusters in amorphous carbon and computational simulation for the fcc and hcp xenon crystalline phases

Abstract

We report the investigation of Xe clusters in amorphous carbon by x-ray absorption spectroscopy (XAS) to understand the properties of solid xenon. Measurements have been performed on xenon L 3 absorption edge at room temperature (300K). Using computational XANES calculation for fcc and hcp structures it was possible to study the XANES fine structure origin and a relation between the x-ray absorption near edge structure and the lattice constant. Comparing those results with our experimental data we determined that the XAS fine near edge structure has a specific behavior for solid xenon and does not have this behavior for gas Xe end Xe diluted in others chemical elements matrices.

The application of synchrotron radiation and in particular X-ray absorption spectroscopy to matrix isolated species

“…EXAFS studies have also been used to study rare gas atoms and clusters in unconventional matrices such as: Ar atoms implanted in amorphous carbon films [260] or Si, SiO2 or HOPG [261]; Ar and Kr atoms in highly stressed amorphous carbon films [260]; over-pressurised Kr bubbles in copper and nickel [262]; Xe bubbles in single crystal silicon. [263]; Kr clusters in Be and Si [264]; Xe bubbles in UO2 [265,266] and amorphous carbon [267]. It should be noted that Winn's experiments [270,271] were carried out with near homeopathic dilutions of 1:50000 compared to the 1:100 used in the EXAFS experiments, and that broadening and multiplets involving shifts of a few wavenumbers are present for concentrations greater than 1:1200, and that this was used to explain the less organized structure than that predicted from the experiments and calculations of Winn [270,271].…”