• 4-ID-D overview.
• Temperature range (Liquid helium flow cryostat): 1.5-300 K.
• Magnetic field up to 6 T.
• Measurement is performed in transmission geometry.
• Diamond phase plates are used to generate circular x-ray polarization.
• Setup is optimized for XANES measurements between 5 and 23 keV and XMCD measurements between 6 and 17 keV.
• Focused x-ray beam using on sample position:
  • ​with KB mirror: ~15x15 microns
  • without KB mirror: ~100x250 microns. Smaller beams are achieved using a slit.

Almax-Easylabs OmniDAC

• Cell material: CuBe
• Type of diamond anvils: standard, partially perforated, and mini combined with fully perforated.
• Various culed diameters are available from 100 to 1000 microns.
• The maximum pressure available strongly depends on details of experiment and type anvils. In most cases the maximum pressure is ~ 100 GPa.
• In-situ ruby fluorescence is used for pressure calibration
• Pressure is applied in-situ with a helium gas membrane.
• Silicon oil, 4:1 Methanol:Ethanol, neon and helium pressure media are available.

Carefully preparing the sample to be placed in the high-pressure chamber is a critical step for a successful XANES/XMCD measurement. The first aspect to be assessed is the sample's x-ray absorption length at the relevant energies. The sample thickness should be such that the absorption edge jump is between 0.5-1.5, while maintaining the total absorption length below ~ 2.5. The optimal thickness can be calculated using the tabulated x-ray cross sections (this should be done well ahead of your experiment, please communicate with your local contact if you need help). The second aspect is that the thickness needs to be homogeneous over the x-ray beamsize. This means that powder samples need to be well ground (grain size typically < 2-5 microns), and single crystal samples need have well defined faces. An inhomogenous sample will largely increase the measurement noise, leading to longer scans.