LEED and AES manuals for D133
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Attentions:
1. Vacuum pressure must be less than 1×10-7Torr;
2. The maximum filament is 2.95A;
LEED Operating Instructions
1. Connecting Cables for LEED mode
1.1 Connecting the SCREEN port of LEED-AES Controller to the SCEEN port
of LEED;
1.2 Checking if the GRID 2&3 in LEED is connected to the GROUND cable
(a part of electron gun cable);
2. Preparing LEED Optics
2.1 Make sure the sample is grounded;
2.2 Using the manipulator to transfer the sample to the center of LEED
optics. The reference position is X: 17.885mm, Y: 19.765, Z: 59.4mm.
The sample position is slightly around the reference position for the
reason of relative position of sample to the sample hold. This is an
iterative procedure by the cooperation of LEED Optics focus procedure.
2.3 Approaching the LEED probe to sample until it leave a distance of
15mm;
2.4 Turn on LEED and run the standard mode in OPER mode (This can be
done by selecting program "STARAND" from PROGRAM SEL plus SELECT
knobs). First run filament current to default value or 2.30A, then run
SCREEN to default value or 4KV.
2.5 Adjusting FOCUS, WEHNELT and the Sample Position until we see
diffraction patterns on screen. Then find the zero diffraction pattern
and move it to the center of screen. Increasing WEHNELT and reducing
FOUSE will reducing the size of beam. Usually, the WEHNELT is 1.0V, and
the FOCUSE is about 1.15 - 1.40 beam energy. The GRID2&3 (the retard
voltage) is about 0.5 - 1.0 of beam energy (0.8 is better).
3. Video View
3.1 Open the LEED software and select the manual setup from
measurement menu.
3.2 Click OK to save image.
4. Setting LEED Controller
4.1 Run LEED in PROG mode and then select the specified program such
as STARDAND;
4.2 Enter the preferred parameters and then Press SAVE to save them
into controller.
5. Outgas LEED filament
Outgas the filament of the electron gun while the analysis chamber is
still warm after bake out. Increasing the filament current slowly to a
maximum of 2.8A by observing the chamber's vacuum.
Notes:
(1) There is no need to turn off the controller when switching between
OPER and PROG mode.
(2) Put LEED to STANDBY when there is no experiment running.
(3) Slowly change the filament current.
(4) Pay attention to the SHUT BUTTON. We have reset problem when
turning on the power with SHUT DOWN in ON state.
AES Operation Instructions
1. Switch to AES mode
1.1 Ensure the power is off;
1.2 Setup the cable configuration for AES mode (SCREEN from LEED&AES
controller connected to SCREEN port of AES's preamp, connecting the
preamp to the SCREEN port of LEED/AES spectrometer, and GRID 2&3 from
Lock-in connected to Grid 2&3 port of LEED/AES spectrometer), and then
turn on the power.
2. It will be better to find the sample position by performing LEED
experiment.
3. Run the software AES on PC to performing AES experiment.
4. Using AES software:
4.1 Select new to setup the experiment parameter;
4.2 Press OK to run AES scan.
4.3 To view the element, select the peak.
Notes:
1.1 Disconnect the preamp when changing high voltages on electron gun
or stop AES experiment;
1.2 Disconnect the video DAQ cable when stop the AES experiment because
the power supply for video is provided by computer.
