• New class of Cylindrical Mirror Analyzers

• Why is SUPERCMA a superior device?

• Single Pass versus Double Pass

• The different models

^SUPERCMA, a new class of Cylindrical Mirror Analyzers

SUPERCMA is a major improvement of the classical cylindrical mirror analyzer (CMA).
The classical CMA design, with its unbeatable combination of compact size, highest sensitivity, and integrated electron gun, is the standard design for Auger Electron Spectroscopy. In contrast to these advantages, the CMA design has several less advantageous features like a short working distance, critical sample positioning, and a very small acceptance area on the sample. 

The new SUPERCMA design offers all the advantages of the regular CMA and overcomes all the weaknesses of its predecessor. The working distance is very convenient, ranging from 35 mm to 55 mm depending on the model. Sample access and positioning are much easier, and changes in sample position are more than ten times less critical. The sample distance to the analyzer can be changed by a several millimeters still maintaining all characteristics. The accepted sample area is as large as 3 mm in diameter, eliminating the constraint of using a well focused beam for analysis. This is a major advantage when performing Scanning Auger Microscopy with the analyzer, because the scanned area can be large.

In addition, the SUPERCMA offers new features which were until now considered characteristic of only larger, powerful hemispherical systems.

• The analyzer is able to work simultaneously in analog and pulse counting modes. Two modes of operation can be selected: the constant energy resolution or the constant resolving power modes.
• The energy resolution is electronically controlled and ranges from less than 100 meV up to 6 eV without any mechanical adjustment of the sample or any changing of diaphragms. Resolution is solely computer controlled, and can be set for each individual acquisition window. 
• Resolution is excellent and allows high resolution Auger spectroscopy, energy loss spectroscopy and Photoelectron spectroscopy (XPS and UPS).
• The large acceptance angle is ideally suited to routine AES and Scanning Auger Microscopy. The use of a movable diaphragm in front of the analyzer allows angular resolved measurements, with the advantage of the variation of the take off angle, a capability not offered by hemispherical analyzers. This option allows Ion Scattering Spectroscopy (ISS) and scanning ISS.

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Why SUPERCMA is a superior device:

The key to these surprisingly good features is the use of new properties of the cylindrical mirror geometry. In contrast to the standard CMA geometry, where the electron beam enters and exits the cylindrical field passing through slits machined into the inner cylinder, the new super CMA accepts electrons entering between the two cylinders as shown in Figure a). This patented geometry has good focusing properties and a large working distance. Combined with a high precision retarding field optic, the electron energy through the cylindrical mirror field, i.e., the pass energy, is variable and so is the energy resolution.

Figure a)

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Single Pass versus Double Pass

The single pass design, as described above, is ideally suited for standard AES investigations in analog and pulse counting modes. A more powerful instrument is obtained combining two CMA fields in series, as shown in Figure b). This double pass geometry uses the first element as an input lens and the second as the energy analyzer. The main advantage of this design is that the sample area as seen by the analyzer is well defined by the input optic. This configuration allows XPS measurements where the sample area is widely exposed to the X-ray beam. In this case, the analyzed area on the sample is well defined and limited to a small circular spot in the millimeter range.

Figure b)

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Members of the ^SUPERCMA family