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MODELS

 

The flange-on DEEM spectromicroscope shown below can be operated in three different working modes, depending on the field configuration in the α-SDA. When the magnetic deflector is switched off and the potential of the lower hemisphere equals to the microscope potential (no deflecting field), the geometry has the linear structure of the classical. The further mode of operation, i.e. “energy selective k-projection”, is reached stepwise. First of all the magnetic deflector is gradually activated to get the electron beam through the opening in the lower hemisphere onto the intermediate test screen, which leads to the initial scheme for the energy selective k-projection (indicated by the broken line). After the deflection by an angle of 15o is assured, the lower hemisphere can be activated (whereas the upper one remains “switched off”) to bring the beam into the “diffraction” column. Now only one parameter has to be changed, namely the potential of the upper hemisphere, to pass from energy selective  k||-projection into energy selective real image observation. Thus, the activating and deactivating of this potential assures a fast and reversible transition between the two main operation modes and as a consequence enables a quasi- simultaneous reciprocal and real space imaging.

p2 models peem1p2 models spec leed1p2 models spec leem1

 

 
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