Small angle X-ray scattering measurements for fluid selenium near the liquid–vapour critical point

Abstract Small angle X-ray scattering (SAXS) measurements for fluid Se near the liquid–vapour critical point have been carried out to investigate the correlation between the density fluctuation and electronic properties of fluid Se near the isochore of critical density. For this purpose, correlation lengths of density fluctuations of fluid Se have been measured precisely at different temperatures and pressures near the critical point. In this experiment a side-by-side multi-layered mirror for Mo Kα1 is used for monochromatizing and focusing X-ray beam for the first time. A better fitting condition to calculate the correlation lengths of the density fluctuation is found. Larger values of the correlation length of the density fluctuation are obtained near the critical density region.