UPS Analysis on the Kratos Axis Ultra

Set up conditions:
UPS Mode
Detector 3
5 or 10 eV pass energy (5 eV preferred)
Slot or 110 micron aperture (these two conditions limit the count rate, must keep count rate below 1 million or damage to the detector can occur)
Apply a negative bias voltage to the sample using the BNC connection used for monitoring sample current. A 9-12V negative bias works well.
Charge nuetralizer off
Input measured voltage into sample bias on Kratos computer (Engineering mode, Manual Workspace, Parameters page)

Sample Parameters:
Sample conducting and well grounded to holder (stub preferred but not necessary)
For work function analysis of bulk samples the surface must be sputter cleaned, or sputter cleaned and annealed

Measurement of Work Function:
Work Function formula:
Work Function = hv-(Ecut-off - Ef)
where hv = 21.21 eV for He(I), Ef is the Fermi energy (BE scale) and Ecut-off is the secondary electron cut-off (BE scale) (i.e. Ecut-off - Ef is the absolute difference between the two values).

A pdf file showing how to calculate Ef and Ecut-off from a UPS spectrum can be found here.