1.5 (V) x 10 (H) µm FWHM Focus Project

Photograph of the new KB mirror system
Photograph of the new KB mirror system

1.5 (V) x 10 (H) µm FWHM Focus Project - The scattering cross-section for X-ray Raman is orders of magnitude smaller than diffraction.  This presents significant challenges, particularly for measurements at high pressure, where the surrounding gasket and diamond in a diamond anvil cell contribute unwanted background. To minimize diamond background scattering for measurements of H2 electronic excitation, we successfully commissioned a new mirror set to focus the beam down to 1.5 (V) x 10 (H)µm FWHM. The mirror system consists of a 400mm horizontal mirror and a 200mm vertical mirror. A 10µm pinhole is put at ~7mm away from sample position. We collected H2 inelastic X-ray scattering signal from a 60µm sample at 12GPa.  Future plan is to do measurement at mbar and low temperature.

 

Figure: Focus profiles of the new mirror system with FWHM 1.5µm in vertical (top panel) and 9.5 µm in horizontal (bottom panel) directions.