Before starting the measurement select a proper analyzer slit (black knob on the analyzer).
Back side of the analyzer and black knob for slit selection. Current reading is 100.
Narrow slit:
+ better k-resolution perpendicular to the slit
- more difficult to focus and less counts.
Curved slit:
+ flat Fermi level and constant energy surfaces
- makes a curved cut in k-space
Straight slit:
+ makes a straight cut in k-space
- curved Fermi level (energies need to be corrected programmatically).
We usually start with 400.
850 = Fully open, only for pumping down!
Beamline exit slit
Beamline (BL) exit slit vertical width is controlled manually with a knob behind the electronics rack.
With a smaller slit you improve energy resolution, but get less counts.
Plateau area (~140um) is a good starting point.
Beamline resolution for a given BL exit slit and photon energy can be estimated using an Igor script provided below (beamline parameters correspond to 1^2):
