Checklist before starting with a new sample or I0 measurement

Last modified by sjhuotar@helsinki_fi on 2024/02/07 06:21
  • Check count rate in the scan range (before and above the edge). The NaI scintillator can take ~50 000 cps maximum. If the count rates are always below 10 000 cps, you may want to increase the power source current within the limits allowed by the specifications (todo: scan and upload the specs sheet). If the count rates are over 50 000 even with 2 mA current, your sample is too thin (see how to optimize sample thickness - todo: insert the link here)
  • Check the detx/dety calibration (detx scan should be centered at beginning and end of the energy scan range, width ~horizontal slit size (usually 5 mm) and the scans should have a flat top.
  • Check the vertical tilt adjustment of the monochromator holder (the micrometer screw behind the monochromator holder) (todo: add instructions how to do)
  • If using the He chamber: Check that there is helium in the bottle (if below 50 bar, consider ordering new one. Ask Simo). Check that there is He overpressure in the chamber (seen easily from the analyzer side Kapton window; should be slightly inflated). The blue hose should be in water and bubble slightly when the hose end is pulled toward the water surface. Push the hose below the water surface until no bubbles come out - this defines a slight overpressure.
  • Check that your scan ranges make sense: xx eV below the edge, xx eV above; use standard macros if unsure.