LEED

Sample characterization using Low Energy Electron Diffraction

1. Check that both LEED cables are connected, and make sure that LEED has been degassed.

2. Make sure that LEED is retracted and there is nothing in the way, then move sample to a saved LEED position (if available). Insert LEED while looking inside the chamber.

DANGER: For manual approach use the following order: first move polar angle, then move the LEED forward towards the sample, then move the y axis and finally adjust x and z. The final distance of the sample holder should be ... from the LEED electron gun.

Be careful when performing any movement: you can seriously damage the LEED if manipulator touches the instrument. Always look inside the chamber while moving! Be also very careful after you finish the LEED measurement: before performing any rotation move the y axis to 0 and retract the LEED.

Do NOT move LEED with opened shutter!

3. Open the LEED shutter gently, and fix it by turning the screw on the shutter handle.

4. Cover all the windows of the prep chamber with aluminum foil and cover the outer LEED window with a black cap (it has a small hole in the middle for eye or camera, see the picture below).

5. Switch on the LEED power supply (SPECS). Press down the Cathode knob and rotate clockwise until it clicks. Set cathode current to 2.4 A.

6. Slowly turn the Screen knob to the operating voltage (6 kV).

7. Roughly find sample position. Adjust the offsets of L1 and L2 lenses until you see sharp LEED pattern.

8. Set the desired electron beam energy with Energy knob.

9. When you finish reduce the Screen HV to 0V and reduce the filament current to 0 (until it clicks). Switch off the power switch.

DANGER: Move the y axis to 0, close the LEED shutter, move the LEED backwards, then move the polar angle. Watch all the movements closely!