Miniature diamond anvils for X-ray Raman scattering spectroscopy experiments at high pressure

X-ray Raman scattering (XRS) spectroscopy is an inelastic scattering method that uses hard X-rays of the order of 10   keV to measure energy-loss spectra at absorption edges of light elements (Si, Mg, O etc.), with an energy resolution below 1   eV. The high-energy X-rays employed with this technique can penetrate thick or dense sample containers such as the diamond anvils employed in high-pressure cells. Here, we describe the use of custom-made conical miniature diamond anvils of less than 500   µ m thickness which allow pressure generation of up to 70   GPa. This set-up overcomes the limitations of the XRS technique in very high-pressure measurements (>10   GPa) by drastically improving the signal-to-noise ratio. The conical shape of the base of the diamonds gives a 70 ° opening angle, enabling measurements in both low- and high-angle scattering geometry. This reduction of the diamond thickness to one-third of the classical diamond anvils considerably lowers the attenuation of the incoming and the scattered beams and thus enhances the signal-to-noise ratio significantly. A further improvement of the signal-to-background ratio is obtained by a recess of ∼ 20   µ m that is milled in the culet of the miniature anvils. This recess increases the sample scattering volume by a factor of three at a pressure of 60   GPa. Examples of X-ray Raman spectra collected at the O K-edge and Si L-edge in SiO2 glass at high pressures up to 47   GPa demonstrate the signific...

Source: Journal of Synchrotron Radiation - December 15, 2016 Category: Physics Authors: Petitgirard, S. Spiekermann, G. Weis, C. Sahle, C. Sternemann, C. Wilke, M. Tags: X-ray Raman scattering high pressure miniature diamond anvils SiO2 glass research papers Source Type: research