Chapter
8 Analyzer Checks
8.1 Independence of Peak Position with Pass Energy
Because of the large number of slit and lens combinations, the energy calibration of the
analyzer was not done for each slit combination. SPECS delivers the analyzer with the
correct parameters for the common slit combinations. To check the independence of
the peak position with pass energy for a desired slit combination please follow the pro-
cedure below:
Transfer a silver sample into the system. Warm up your electronics first!
Adjustments:
Excitation Mg Kα
X-ray power 100 W
Slit desired slit combination, e.g. entrance: largest slit / exit: open
Mode Medium Area
Binding energy range 365 - 375 eV
Scan 1
Dwell Time 100 msec
Energy step 25 - 30 meV
Pass energy ~ 15eV
Run a spectrum. Set a second pass energy (for the above described slit combination e.g.
of about ~5 eV). Repeat the measurement. Compare the spectra. If the voltages are cor-
rect, the peak-maxima of both spectra have to have the same energy. The peak posi-
tions of both spectra should not differ by more than 100 meV. For a symmetrical peak
the peak position is independent of Epass. This is not true for Auger electron peaks since
the peaks are intrinsically asymmetrical.
You can also display the single channels for the accumulated spectra. The difference in
the peak maxima for each channel indicates the quality of the MCD Calibration (see sec-
tion 7.3). If the peak energy weakly depends on pass energy, perform the “MCD Calib-
ration” (see section 7.3, page 60). If the calibration does not fix the problem and/or
there is a strong dependence please refer to section “” on page . Short circuits or sup-
ply failure can cause such behavior. After voltage check please contact SPECS and send
some spectra as well as the measured voltages to help diagnosis of the exact problem.
Note that there is a weak dependence of the peak energy on beam position at the
sample and the size of the illuminated area. Because SPECS calibrates the analyzer with
PHOIBOS 65
To Next Page
Loading...
Need help?
General