Sample holder for small-angle X-ray scattering measurements and density fluctuation of supercritical xenon

We constructed a sample holder of Xe for small-angle X-ray scattering (SAXS) experiments. The holder was designed to attain a very small path length of a sample that corresponds to the large X-ray absorption of Xe. For the easy and convenient operation of the experiments in synchrotron radiation facilities, a cell was contrived so as to vary the path length despite the presence of a high-pressure sample inside. The path length varies from 0.05 to 3.5 mm. The holder is applicable not only to supercritical Xe but also to liquids, solutions and other supercritical fluids under highly pressured conditions using relatively low-energy X-rays. SAXS measurements were carried out for supercritical Xe in a wide density range. Density fluctuations for the fluid at various thermodynamic states were obtained from SAXS signals.