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- Move the edge energy about 20 eV above the nominal edge energy. At this point,
- I1 transmission through sample should be minimized
- I2 transmission through foil (on back ion chamber or on scatter reference) should be minimized
- I2 fluorescence from foil or compound on CALVERT holder should be near a maximum
- I3 fluorescence from your sample (if using PIPS/Lytle) should be near a maximum
- Make sure that the signal you read on I0 through I3 is > 0.5 and < 4
- Move the MONO 20-50 eV below the edge energy. At this point,
- I1 transmission through sample should be maximized
- I2 transmission through foil (on back ion chamber or on scatter reference) should be maximized
- I2 fluorescence from foil or compound on CALVERT holder should be at a minimum
- I3 fluorescence from your sample (if using PIPS/Lytle) should be near a minimum
- Make sure that the signal you read on I0 through I3 is > 0.5 and < 4
- Check I0 through I3 signal gains while you are at "stop energy" (highest energy) of your XAS scan energy region. This number can be found by going to the Regions window and selecting the scan region you will use. Look towards the bottom of the window for the "stop energy" value. At this point,
- I0 through I3 may be larger than their values when MONO is at or below the edge
- Make sure that the signal you read on I0 through I3 is > 0.5 and < 4
- Make sure that the signal you read on I0 through I3 is > 0.5 and < 4
- Move the MONO below the edge energy where I2 signal will reach its max. Check again that the signal you read on the ion chambers is > 0.5 and < 4.
- After changing gains, check offsets by closing beam shutter. You want the ion chamber signal to be a positive number which is as close to zero as possible. Adjust the offsets in the Ion Chambers tab.
- After changing offsets, collect offsets on the detector file you plan to use.
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- Run the default queue with a region made for calibration scan at that edge. If you do not have one, you can use the "Region Wizard" to create a "Foil" region.
- If running at low energy with calibration foil or compound on the motorized CALVERT holder, set CALVERT to its IN value (about 37.5)
- Open plotter
- Plot different quantities depending on calibration detection technique:
- If foil in front of I2 back ion chamber, plot log
- (I1/I2)
- If foil in scatter reference in front of I0 ion chamber, plot log(I0/I2)
- If foil or compound on CALVERT holder, plot I2/I0 or DIODE/I0
- When the sweep is complete, while still in the plotter window- click “Modify” and then “Derivative”
- Copy the highlighted value for the energy of the first large peak in the derivative (autoselected by the plotter in the list of energies)
- In the Mono controls:
- Send the Mono to the copied value from the derivative
- In the Calibrate tab: Set to the known/book value.
Now you are able to move on with loading and aligning samples, windowing the detector (if using the 30 Element Ge 7-element Vortex detector), and running measurements!
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