Resonant Elastic and Inelastic X-ray Scattering (REIXS)
Resonant Elastic and Inelastic X-ray Scattering (REIXS)

RIXS Endstation Manuals

RIXS Data Collection

Endstation Software

Data Acquisition Software

  1. Open a terminal and login to the data acquisition computer by double-clicking runRIXS_ES on the desktop.

  2. Start SPEC software on the RIXS ES by typing runRIXS.

    1. Report any errors during starting to the beamline staff.

    2. The procedure for recovering in case of an accidental terminal closure or computer issue is identical to above.

Data Visualization Software

  1. Start dataGUI by double-clicking runRIXS_GUI icon.

    1. It will take a few seconds to load

Data Analysis Software

  1. Start the analysis software, Jupyter Notebook by double-clicking the runRIXS_Analysis icon.

    1. This will launch a terminal to start juptyer notebook and then launch a web browser.

    2. The analysis notebook can only be run on one computer at a time.

    3. Documentation can be found here: Data Reduction Notebook

Beamline EPICS Screens

  1. Start the EPICS EDM screen by double-clicking the REIXS_Users icon.

    1. This will launch window to view some beamline variables within EPICS.

    2. Launch additional relevant windows or strip-tool using the appropriate buttons.

Setup REIXS Beamline

  • These steps only need to completed if you are starting for the first time, or if you are changing elemental edges.

Setup EPU

  1. Check the current settings of the EPU using statEPU or observe the parameters on the dataGUI.

  2. Select the EPU polarization using setEPU polar. Examples below:

    1. Typically one uses horizontal polarization for almost all experiments.

    2. Vertical polarization is used to for spectrometer calibration or for specific experiments.

      1. setEPU polar lh - linear horizontal (default)

      2. setEPU polar lvn - linear vertical negative (use for calibration)

      3. setEPU polar lvp - linear vertical positive

      4. setEPU polar li - linear inclined

      5. setEPU polar cl - circular left

      6. setEPU polar cr - circular right

  3. Select the EPU harmonic using setEPU harmo. Examples below:

    1. Use the correct harmonic to ensure best higher order rejection and optimal photon flux.

      1. setEPU harmo 1 - set EPU harmonic to ”1” (95 - 850 eV)

      2. setEPU harmo 3 - set EPU harmonic to ”3” (850 - 1500 eV)

    2. Note: There is currently a macro to automatically set the harmonic, therefore no setting is needed. However, this will need to be disabled if you want to change to a non-ideal setting.

Setup Mono

  1. Check the current settings of the Mono using statMONO or observe the parameters on the dataGUI.

  2. Use moveM to select the mirror and moveG to select the grating for the desired energy range.

    1. Ensure that you select the mirror coating before selecting the grating.

    2. Generally, you can use the following:

      1. – Carbon mirror and Au LEG when using 100 eV to 250 eV energy range.

      2. Nickel mirror and Ni LEG when using 200 eV to 750 eV energy range.

      3. Silicon mirror and Au HEG when using 350 eV to 1500 eV energy range.

    3. Carbon mirror and Au LEG grating

      1. If changing from Nickel/NiLEG:

        1. moveE 250

        2. moveM Carbon

        3. moveG AuLEG

      2. If changing from Silcon/AuHEG:

        1. moveE 600

        2. moveM Nickel

        3. moveG NiLEG

        4. moveE 250

        5. moveM Carbon

        6. moveG AuLEG

    4. Nickel mirror and Ni LEG grating

      1. If changing from Carbon/AuLEG:

        1. moveE 250

        2. moveM Nickel

        3. moveG NiLEG

      2. If changing from Silcon/AuHEG:

        1. moveE 600

        2. moveM Nickel

        3. moveG NiLEG

    5. Silicon mirror and Au HEG grating

      1. If changing from Carbon/AuLEG:

        1. moveE 250

        2. moveM Nickel

        3. moveG NiLEG

        4. moveE 600

        5. moveM Silicon

        6. moveG AuHEG

      2. If changing from Nickel/NiLEG:

        1. moveE 600

        2. moveM Silicon

        3. moveG AuHEG

  3. Move to the desired energy using moveE

    1. Typically the excitation energy is 30-40 eV above the edge.

    2. Consult electron binding energy values or consult beamline staff.

Setup Spectrometer

  • Check the current settings of the Spectrometer using statXES or observe the parameters on the dataGUI.

  1. Select the appropriate grating, use setXES.

    1. Grating selection is based on a balance between efficiency and resolution.

    2. Consult charts on wall for specific performance. In general:

      1. XLEG: 90 - 200 eV

        1. setXES XLEG

      2. LEG: 200 - 400 eV

        1. setXES LEG

      3. MEG: 400 - 650 eV

        1. setXES MEG

      4. HEG: 650 - 1000 eV

        1. setXES HEG

  2. Move the spectrometer using moveXES

    1. The location of the emission line is generally 10 - 15 lower than the absorption edge.

    2. Consult tables for binding energies or emission energies.

      1. Alternatively ask beamline staff for assistance.

    3. The spectrometer requires image correction for optimal resolution and therefore, pre-work is required.

      1. Use a location out of the list below (< 5 eV and < 1 deg) to ensure correct image processing.

      2. For example:

        1. moveXES 520 -1

          1. move to 520 eV with -1 deg offset on the LEG.

    4. After movement is complete ensure the correct shift file is loaded, otherwise software will report NULL and no image correction will be used.

  3. Optimize the position of the spectrometer with 5 eV in later step once your sample is aligned.

SHIFT FILES AVAILABLE

  • XLEG 80 eV at 4 deg

  • XLEG 93 eV at 4 deg

  • XLEG 114 eV at 4 deg

  • XLEG 120 eV at 4 deg

  • XLEG 126 eV at 4 deg

  • HRMEG 450 eV at 2 deg

  • HRMEG 500 eV at 0 deg

  • HRMEG 525 eV at 2 deg

  • HRMEG 528 eV at 1 deg

  • LEG 177 eV at 2 deg

  • LEG 276 eV at 0 deg

  • LEG 380 eV at 0 deg

  • LEG 390 eV at 0 deg

  • LEG 400 eV at 0 deg

  • LEG 455 eV at 0 deg

  • LEG 515 eV at -1 deg

  • LEG 520 eV at -1 deg

  • LEG 575 eV at -1 deg

  • LEG 645 eV at -1 deg

  • LEG 675 eV at -1 deg

  • MEG 276 eV at 4 deg

  • MEG 380 eV at 1 deg

  • MEG 390 eV at 0 deg

  • MEG 400 eV at 0 deg

  • MEG 455 eV at 0 deg

  • MEG 485 eV at 0 deg

  • MEG 515 eV at 0 deg

  • MEG 520 eV at 0 deg

  • MEG 575 eV at 0 deg

  • MEG 625 eV at 0 deg

  • MEG 645 eV at 0 deg

  • MEG 675 eV at 0 deg

  • MEG 710 eV at 0 deg

  • HEG 645 eV at 2 deg

  • HEG 675 eV at 2 deg

  • HEG 710 eV at 1 deg

  • HEG 785 eV at 0 deg

  • HEG 860 eV at 0 deg

  • HEG 940 eV at 0 deg

  • HEG 1020 eV at 0 deg

  • HRHEG 925 eV at 0 deg

Setup Datafile

  • Before attempting any data collection, it is best to setup the file for saving data. Some tips are:

    • Do not use a new filename for each scan.

    • Do not include spaces or math symbols in the filename.

    • Group scans together either with sample and/or element measured.

      • This will depend on the number of scans, try to keep fewer than 100 scans per file.

  1. Set datafile name using newfile – For example:

    1. newfile test_file

      1. No extension is needed, all file extensions will be changed automatically.

      2. If you wish to resume adding to existing files, just specify the name and it will change files.

Aligning Samples

  • While it is tempting to align samples only prior to the measurement, it is best to align all samples, save their positions and then proceed. This will significantly improve throughput.

  • The sample alignment is achieved using the camera cross-hairs. The principle is that if the cross-hairs are co-located on the same position, the beam is there and the sample is in focus.

  1. Turn on the beam using setBEAM on.

  2. Ensure the chamber light is on using setLAMP

    1. Use setLAMP on and setLAMP off

    2. Can be toggled on or off using LAMP button GUI alignment tab.

  3. Roughly change the sample depth to ensure the cross-hairs are properly aligned in that they appear at the same sample position.

    1. Use umvr ssd to add or subtract sample depth. For example:

    2. umvr ssd 0.5 to add 0.5 mm of sample thickness.

  4. Roughly position the sample in the beam using a combination of umvr ssv and umvr ssh.

    1. umvr ssv will move the sample vertical position; positive vertical moves the sample upward.

    2. umvr ssh will move the sample horizontal position; positive horizontal moves the sample to the right.

    3. It is possible to combine movement for faster alignment such as:

      1. umvr ssv 1 ssh 2 – All units are in mm.

  5. Use a line up scan lup to precisely align the sample.

    1. For example lup ssh -1 1 10 1 will scan relative -1 mm to 1 mm with 0.2 mm steps counting for 1 s each point.

    2. ALWAYS scan positive and ensure the step size does not fall for below 50 um for ssh and 25 um for ssv.

    3. Make use of all detectors, tey, sdd and mcp, to assist with determining good sample positions.

  6. Save your sample position using setSS. For example:

    1. setSS Sample_1

      1. Same rules for filenames, no spaces or math symbols.

      2. If you want to re-save an existing sample, you will be asked to confirm the overwrite.

  7. Move samples using moveSS

    1. For example: moveSS Sample_1

    2. Sample moves can be added to the macro files for automated experiments.

Collecting XAS Spectra

  • When collecting XAS spectra, it is important to ensure that all detectors are in an acceptable range.

  • Adjusting detectors is easiest done above the edge, non-resonant. However, it may be necessary to collect a quick XAS scan and then move to a resonance to adjust the detectors.

  1. Move above the absorption edge using moveE, typically 30 - 40 eV higher.

    1. For K-edges, typically above the edge is 75-80 % of the maximum intensity.

    2. For L-edge, you may need to a rough scan and move to the L3 resonance.

  2. Count for 1s using ct to determine the event rate on detectors.

  3. Adjust the count rate on the SDD A (sdda) using the overall beamline flux, setFLUX

    1. Ensure the count rate is < 100,000 cps, typically set to 80,000 cps above resonance.

    2. Reduce or increase the flux using setFLUX where the argument is % nominal, 100% is largest.

    3. For example: setFLUX 100 to set to maximum.

    4. For example: setFLUX 50 to reduce flux to 50% of maximum.

  4. Once beamline flux is adjusted, adjust amplifiers using setAMP to optimize dynamic range.

    1. Beamline flux meter is Mesh (i0), adjust using setAMP i0 down or setAMP i0 up.

    2. Sample current meter is Sample (tey), adjust using setAMP tey down or setAMP tey up.

    3. Changes the rate by a factor or 2 or 2.5.

    4. Ensure rate does not exceed 1,000,000 cps.

    5. Typically, set to 400,000 - 600,000 cps is ideal.

    6. For the sample current (tey), 400,000 - 600,000 cps is okay above the edge for K-edge. L-edge may need to be lower.

    7. Sensitivity can be set explicitly using setAMP tey 10nA/V for example. This is best for macros.

  5. Check the count rate once again using ct

    1. These settings can be added to a macro file to speed up the experiment.

  6. Scan the energy using Escan.

    1. Typically ones does a quicker rough scan to check beamline calibration and ascertain where there are resonances.

    2. It is also advisable to always do two XAS scans to check radiation damage, either two normal scans added together to produce the final spectrum, or two quick scans followed by a longer final scan. The latter will aid in detector optimization.

    3. For example: Escan 390 395 25 405 200 415 100 425 50 5 will scan from 390 eV to 425 eV with step regions 0.2 eV, 0.05 eV, 0.1 eV and 0.2 eV with a count time per point of 5 seconds.

  7. Do XAS calibration prior to experiment.

Calibrating XAS Spectra

  • Typically, one uses a reference material to calibrate the XAS energy.

  1. Select an appropriate reference material, either simple oxide or nitride.

  2. Measure an XAS spectrum with the required precision at the resonances used for calibration.

    1. 50 meV step size when 100 - 700 eV

    2. 100 meV step size when 700 - 1200 eV

    3. 200 meV step size above 1200 eV

  3. Complete a reference XAS scan before an after the experiment per edge.

    1. If running multi-day experiment, complete at least twice per day.

Collecting XES Spectra

  • While XES spectra seem to be a separate measurement, they are in fact the same as XAS, in that you acquire an XES spectrum at every point.

  • Typically for XES, you simple count longer at specific energy.

  1. Ensure that you have not left the flux reduced from previous XAS scans, setFLUX 100.

    1. Typically all XES measurements are completed using full beamline flux.

  2. Move the beamline energy to the required energy, moveE.

    1. Typically, one does at the very least one non-resonant XES, about 30-40 eV above the edge.

    2. Additional excitation energies can be selected based on peaks in the corresponding XAS spectra.

  3. Ensure sample is in focus using cameras or pinhole.

    1. Typically, the camera cross-hairs are sufficient to ensure the sample is in focus, provided the cross-hairs are located at the sample sample position.

    2. If you are in doubt or have some challenge viewing your sample, you can use the pinhole to determine the focus location.

      1. Set pinhole in place using setXES pinhole.

      2. Count for 5s using ct 5.

      3. Toggle image on the lower left plot on the dataGUI.

      4. Use umvr ssx 0.1 or umvr ssx -0.1 successively to place the image centred vertically at channel 127.
        Direction is inverted, i.e. negative motion moves the image up.

      5. Save the sample location using setSS.

      6. Place the mask back in place using setXES mask.

      7. Un-toggle image on the lower left plot on the dataGUI.

  4. Determine the appropriate count time for the spectrum using ct.

    1. Complete a 10s count ct 10.

    2. Determine the total time required to achieve the require statistics.

    3. Ideally, the best spectrum would have 10,000 peak counts per channel, but 1000 counts would be minimum.

    4. For spectra where the point spacing is small < 50 meV, the adjacent channels can be binned to increase the count rate.

  5. Collect XES spectra using Tscan

    1. Collect for a total time with 30s exposures:

      1. Tscan 360 counts for a total of 360s.

    2. Collect for a total time with custom exposure time:

      1. Tscan 360 120 counts for a total of 360s with 120s exposures.

    3. Collect for a total time with custom exposure time and setting the excitation energy:

      1. Tscan 360 120 420 counts for a total of 360s with 120s exposures at 420 eV.

    4. If the energy is not specified, it will be acquired at the current beamline energy.

  6. Do XES calibration prior to experiment.

Calibrating XES Spectra

  • The calibration of the XES occurs relative to the XAS, with the XAS used as the reference from other beamtimes.

  • The calibration consists of 5 elastic peaks and two reference spectra.

  1. Collect resonant elastic scattering peaks on a bare material, stainless steel plate is okay, but Indium foil or Gold foil is better.

    1. Place beam on bare scattering target using umvr ssh and umvr ssv

    2. Set EPU polarization to linear vert- using setEPU polar lvn

    3. Select 5 energy locations distributed throughout the XES energy window.

      1. Typically one at the centre and two on either edge.

    4. Collect XES such that the peak counts is 1000 for each excitation.

    5. Set EPU polarization back to linear horizontal using setEPU polar lh

    6. Move to the reference compound and collect a non-resonant XES spectrum.

    7. Move excitation to the first peak and collect a resonant XES spectrum

  2. Complete a reference XES scan before and after the experiment per edge.

    1. If running multi-day experiment, complete at least once per day.

Collecting XEOL Spectra

  • Collecting XEOL presents a challenge in that the optical output is not correlated to x-ray absorption.

  • Special care needs to be taken to ensure you take quality XEOL spectra.

  1. Set the desired energy using moveE.

    1. Typically XEOL is strongest at lower energy and before the XAS edge.

  2. Determine the correct frame rate. Set the frame rate using setXEOL rate, where rate is in seconds.

    1. Set the rate such that the detector is not clipping at 65,000 counts, but sufficient that the spectra are good quality, > 30,000 counts.

    2. For example: setXEOL rate 10 sets the frame rate to 10s.

  3. Collect XEOL spectra using Tscan

    1. Ensure the exposure time matches the frame rate. For example Tscan 300 10.

      1. You can see the exposure time before the Tscan using setXEOL rate.

    2. The exposure time can be a multiple of the frame rate also.

  4. Take a back ground spectrum with the same time rate, typically just complete the same scan with the beam off.

    1. setFLUX off

    2. Tscan 300 10

    3. setFLUX on

      1. The background spectra need to be in the same file as the data you want to use it for, then specify background scan in notebook plotting.

      2. Collect at least 10 frames for the background to ensure averaging the readout noise.

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