How to align your sample visually at End-station 2
- Put CeO2 standard on goniometer stage, and align it on X-ray beam using Sample motors X, Y, Z. Trajectory of CeO2 would also be helpful.
- Put Upstream and Downstream laser lenses in, and focus sample chamber on laser viewing screen listed under Video menu.
This provide to mark the x-ray beam position on the laser viewing screen (green circles). Then, take the CeO2 standard out.
Put the ambient single crystal sample (represented by white circle below) glued on goniometer head in, and get it on laser viewing screen (bringing sample into green circle) via playing with Sample motors X and Y only. Please make sure sample rotation=0 deg.
- The next step is to align the sample rotation axis on the x-ray beam. To do this, rotate sample to -90°, and then focus it on laser viewing screen using motor sample Z, and note the sample Z position {lets say sample Z(-90)}. We usually do not need down stream side anymore. So just watch upstream side.
- Rotate sample to +90° , and then focus it on laser viewing screen using sample Z, and note the sample Z position {lets say Z(+90)}.
- Move sample rotation to 0 °. Calculate ΔZ = |Z(+90) - Z(-90)|/2 and move sample Z to the mid-point.
- As a double check, rotate sample from -90° to +90°, and watch sample on laser viewing screen.
How to align your sample at End-station 2 using x-ray
Sample is set on the Huber stage, and aligned to the x-ray beam with measuring the transmitted intensities through X and Y scans using the PIN-diode. In order to center the sample onto the rotation axis, the absorption profile of the sample is scanned along the sample x-stage across the X-ray beam at two different rotation angles. The shift of the sample along the x-stage owing to the rotation divided by the rotation angle gives the offset of the sample from the rotation axis parallel to the beam. With this approach, samples can be placed onto the rotation axis of ES 2 with a reproducibility of better than 2 𝛍m.
