title: Miniature diamond anvils for X-ray Raman scattering spectroscopy experiments at high pressure.
abstract: 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 µm 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 µm 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 SiO2glass at high pressures up to 47 GPa demonstrate the significant improvement and potential for spectroscopic studies of low-Z elements at high pressure.
authors.affiliation: University of Bayreuth, Bayerisches Geoinstitut, Universitätsstrasse 30, Bayreuth, 95447, Germany.
authors.forename: Sylvain
authors.initials: S
authors.lastname: Petitgirard
authors.affiliation: Universität Potsdam, Potsdam, Germany.
authors.forename: Georg
authors.initials: G
authors.lastname: Spiekermann
authors.affiliation: Fakultät Physik / DELTA, Technische Universität Dortmund, D-44221 Dortmund, Germany.
authors.forename: Christopher
authors.initials: C
authors.lastname: Weis
authors.affiliation: European Synchrotron Radiation Facility, Grenoble, France.
authors.forename: Christoph
authors.initials: C
authors.lastname: Sahle
authors.affiliation: Fakultät Physik / DELTA, Technische Universität Dortmund, D-44221 Dortmund, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Sternemann
authors.affiliation: Universität Potsdam, Potsdam, Germany.
authors.forename: Max
authors.initials: M
authors.lastname: Wilke
keywords: SiO2 glass; X-ray Raman scattering; high pressure; miniature diamond anvils