PHI 5600: Data Acquisition
This section details the five types of data acquisition (survey, multiplex, depth profile, angle profiles, and maps) and the most commonly used data reductions for those types.
The purpose of collecting survey spectra is to determine or confirm the elemental surface composition of the area being analyzed. Since the focus of survey spectra is to obtain elemental information, the instrumental conditions are adjusted to maximize elemental sensitivity. To accomplish this, survey spectra are typically collected using the highest pass energy available (187 eV) and a minimal number of data points (typically 0.8 or 1.6 eV/step). Sensitivity increases linearly with pass energy and is also effected by the number of data points collected.
Another part of the strategy for survey spectra is to use the largest analysis area possible, while confining the analysis area to the feature of interest. Time is also a variable in the collection of a survey. However, the quality of the spectra increases relative to the square root of time. Therefore, it is more efficient to optimize the other critical parameters before adjusting the Time/step value (when focusing on sensitivity).
To collect a survey spectrum, perform the following steps:
- Insert the sample into the system and position the analysis area at the focal point of the optical microscope.
- Determine the required analysis area, select it in the Analyzer/Detector menu, and select the required aperture using the knob the on side of the analyzer input lens.
- Choose the directory where the data should be stored (create a new subdirectory if necessary).
- In the Sample Setup menu, enter a filename and comments about the sample.
- Select Setup Survey from the Acquisition Setup pulldown.
- Item ‘a’ in the ESCA Survey setup menu will allow the previous settings, a previous data file or new settings to be defined.
- Enter the desired data collection time, typically five minutes or less using aperture #4 (800 μm analysis area).
- Select the desired x-ray source, typically the Al monochromator using the 2 mm filament.
- Select Acquire.
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