Photoemission with X-ray source

Starting the X-ray source Switch on the X-ray source chiller under the platform (by button). Switch on the X-ray source power supply in the right experimental rack. Set correctly the position of the sample (usual Θ = 190°) and check it by looking through the analyzer viewport. Approach the X-ray source using the z-retractor towards the sample. Check through the CF160 viewport to avoid collisions. On the X-ray source power supply select Presets, then ↑/↓ for the desired anode (Mg or Al), → (and not OK) and then Activate. Wait until stable operatiing parameters are reached.

Switching off the X-ray source On the X-ray source power supply press Standby. Retract the X-ray source using the z-retractor to a safe distance from the sample (at least 5 cm). Check through the CF160 viewport. If you do not plan to use the X-ray source on the same day anymore proceed with complete switch off: Wait at least 5 minutes to let the source completely cool down after the operation. On the X-ray source power supply press Shutdown. Switch off the X-ray source power supply. Switch off the X-ray source chiller under the platform ( button and Yes).

Measurements with SpecsLab2

1. Switch on analyzer power supply and detector electronics (in the lower part of the right experimental rack) if not yet done.
2. Open SpecsLab2.
3. Check that the analyzer is disconnected from KolXPD and connect SpecsLab2 to the analyzer electronics by selecting Analyzer: Phoibos-Hsa3500 in the button bar. Wait until the analyzer is connected. If an error message appears proceed with Electron analyzer connection troubleshooting.
4. Open Analyzer - Settings, section Sources - Method: XPS, Sources - Server: X-Ray Dummy and then in Sources - Settings... choose the material of the X-ray anode (Mg or Al) if incorrect. This setting will influence the recalculation between binding and kinetic energy so it needs to be periodically changed only if you alternate both anodes during your experiment.
5. Open an older file to repeat the measurements with the same or similar parameters, or create a new one. Each File can contain several Groups of Regions, listed in the tree structure in the left window (entitled Files). Other important Windows are Regions (for changing parameters of several Regions at the same time), Region Edit (changing parameters of the selected Region), Acquisition (for displaying the acquisition progress and remaining time) and Data Window(s) (for displaying the data - EDC curves - usually intensity vs. energy). Many operations on the Regions can be then done in more ways: using the buttons in the main, Region Edit and Data windows, or in the context menu available by right-click on the Region selected in the tree structure in the Files window. Most frequently you will use: Save the file, change curve Color, Clear the Region or Group of already acquired data, Validate it to lock the parameters and Acquire to start the acquisition. An example of the parameters is in the following snapshot:
   

   Name: title of region Method: XPS Analysis Mode: FixedAnalyzerTransmission Lens Mode: MediumArea Range:1.5kV Eexc: 1253.6 or 1486.6 eV according to the X-ray anode used Epass: see table below, usually 20 eV Energy step: see table below, usually 0.1 eV Scans: to have sufficient statistics Dwell Time: to have sufficient statistics, usually 0.1 s

   Region Name and number of Scans can be changed at any time, even during the acquisition. Other parameters can be modified only when the Region is Cleared. Validating the Region may change some parameters if you did not set them correctly.
6. By creating new Regions with desired parameters or by using Copy-Paste of existing Regions you can create the whole set of Regions in one Group, for example wide overview scan and detailed core-level Regions with lower Energy Step and improved statistics (Scans). After that you can use this Group for other experimental steps or other similar samples just by Copying, Pasting, Clearing, Validating and Acquiring.
7. At the end of the acquisition do not forget to Save your data. SpecsLab2 saves the data in .xml format and the files are quite huge, as all 100 channels of the detector and all scans are saved separately. They can be Exported as text files .xy or directly opened and processed in KolXPD.
8. Disconnect the analyzer (by selecting Analyzer: none) if you plan to switch off the electronics or to use KolXPD for following acquisition, as only one software, i.e. either SpecsLab2 or KolXPD, can be connected to the electronics at the same moment.

Parameters

photon energy Eexc 1253.6 or 1486.6 eV for Mg or Al Kα, respectively photon energy resolution 0.7 or 0.85 eV for Mg or Al Kα, respectively pass energy Epass 20 eV (or 10 for very sharp features or intensity above 1 Mcps) analyzer resolution 0.3 eV (or 0.15 eV for Epass = 10 eV) Energy Step 0.1 eV or 0.05 for very sharp features or 1 for wide/overview scan spot size 0.9–3.3 mm see graph → angular acceptance ± 8° can be lowered by iris aperture transmission function T Ekin-0.7 (or Ekin-1 for Epass = 10 eV)

Simplified quantitative analysis

for samples that are perfectly flat and homogeneous in depth, unpolarized light, angle between analyzer and X-ray source 90°:

I = n I₀ σ (1 + 0.25 β) T λ cos θ

where
I = total peak (s) or doublet (p,d,f) area after background subtraction
n = atomic concentration of the element in the sample
I₀ = photon flux (supposed to be constant at chosen X-ray anode)
σ = photoionization cross sections (calculated values for every photon energy are available here)
β = asymmetry parameter (calculated values for every photon energy are available here)
T = transmission function (kinetic-energy-dependent, see table above)
λ = information depth or inelastic mean free path (we use values from IMFP TPP2M software)
θ = emission angle off-normal (usually 20° in our case at manipulator setting Θ = 190°)