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  • PHI 5600: X-Ray Source

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  • The 10-610 x-ray source generates x-rays very efficiently and provides good sensitivity. 
  • A monochromator filters out undesired high energy x-rays, x-ray satellites, and narrows the Al Kα lines, greatly reducing x-ray-induced sample damage.
  • The filtered Al Kα beam eliminates x-ray satellites, eliminating some peak overlaps and, in general, simplifies the spectra and peak identification.
  • The filtered Al Kα beam provides a narrower x-ray energy distribution, increasing the energy resolution and chemical sensitivity of the instrument. 

There may be situations where a peak overlap exists between a photoelectron peak and an Auger peak, changing the x-ray energy can eliminate this overlap; this would be the most common reason to use the non-monochromatic x-ray source.

 

Alignment of the system and sample is critical for optimum performance when using the monochromatic x-ray source.  The x-ray source type is chosen in the Setup X-ray menu or in the Acquisition Setup menus.

The monochromatic x-ray source has two filaments: a 2 mm filament and a 7 mm filament. Physical Electronics recommends using the 2 mm filament, because this will provide the highest sensitivity. Note: the charge neutralization system will effectively neutralize insulating samples under these conditions.

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The x-ray sources flood a relatively large area of the sample with x-rays, and the size of the analysis area is determined by the energy analyzer input lens. The user has control of two variables that effect the size of the analysis area. The first is the size of the aperture in the analyzer input lens. A rotary motion located on the side of the analyzer input lens is turned to select one of five apertures. Aperture 1 is the smallest and 5 is the largest. The aperture also must be selected in the Analyzer/Detector menu to apply the correct lens voltage for the selected analysis area. The second variable is the relative magnification of the input lens. Three magnifications are available: large (1 X), small (1/3 X) and minimum (1/5 X)

 

SELECTING THE X-RAY ENERGY

When first turned on, the Model 50-096 X-ray source power supply needs to be programmed to operate at 15 keV. To do this, perform the following steps:

  1. Press the Local button under Control Select.
  2. Press the Start button for the Water Pump.
  3. Press the High Voltage button above the keypad.
  4. Press the Display/Enter Setpoints button above the keypad. (LED should light.)
  5. Press 1 - 5 - 0 - # on the keypad.
  6. Press the remote button under Control Select.

The 50-096 will retain the 15 keV setting until it is manually turned off or there is a power interruption.

SELECTING A PASS ENERGY

The pass energy determines the energy that detected photoelectrons will have as they pass through the hemispherical analyzer. The lower this energy is, the better the energy-resolving capability of the analyzer is. However, as pass energy is lowered to improve energy resolution, the intensity of the detected photoelectron peaks is reduced. This relationship is nearly linear (when the pass energy is reduced by a factor of two, so is the detected count rate). When elemental information is of primary interest, such as in survey spectra, a high pass energy and a large data step size should be used. When detailed chemical information is being sought, a lower pass energy and smaller data step sizes should be used. By selecting a pass energy that is no lower that necessary to resolve the ESCA peaks of interest, you will maintain as high a count rate as possible and improve the efficiency of your experiments.

 

SELECTING THE SIZE OF ANALYSIS AREA

The x-ray sources of the 5600 flood a relatively large area of the sample with x-rays, and the size of the analysis area is determined by the energy analyzer input lens. The user has control of two variables that effect the size of the analysis area. The first is the size of the aperture in the analyzer input lens. A rotary motion located on the side of the analyzer input lens is turned to select one of five apertures. Aperture 1 is the smallest and 5 is the largest. The aperture also must be selected in the Analyzer/Detector menu to apply the correct lens voltage for the selected analysis area. The second variable is the relative magnification of the input lens. Three magnifications are available: large (1 X), small (1/3 X) and minimum (1/5 X).

The control of lens settings (voltages) is performed in the Analyzer/Detector menu, which is under the System Control pulldown. In this menu, you can select the lens magnification and the correct lens constants for a specific aperture. You must also manually select the correct physical aperture.

The size of the analysis area for a given combination of aperture and analyzer input lens magnification is shown in the following table.

Analysis area for a given combination of aperture and analyzer input lens magnifications.
Analysis Area Size
Aperture #Minimum Small Large
1 30 μm diameter ----- -----
2 120 μm diameter 180 μm diameter 0.4 mm diameter
3 400 μm diameter 600 μm diameter 2 mm diameter
4 800 μm diameter 1100 μm diameter 4 mm diameter
5 0.6 x 2.0 mm 1 x 3.5 mm 3 x 10 mm
Physical Electronics recommends using the minimum mode for most analysis
and selecting as large an aperture as possible for the sample that you have, in
order to maximize sensitivity and minimize data collection time. For Auger
analysis, Physical Electronics recommends using either Aperture 4 or 5 along
with the small or minimum lens area magnification.




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CONTACT: Jorge A. López (jorgelopez@utep.edu

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