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OMICRON Product Line
FOCUS-PEEM with Integral Sample Stage (IS-PEEM)
A key feature of the FOCUS IS-PEEM, besides it’s high resolution, is the integral sample stage (optional) with piezoelectrically
driven sample positioning. It forms one building unit with the body of the objective thus effectively avoiding any possible relative motions of sample and objective. This is a particular advantage
compared to the vibrational problems, which may come with a separately mounted sample manipulator. The distance between the sample plane and the objective can be mechanically preadjusted thus
avoiding time-consuming in-situ adjustment. Since, however, in certain cases a manipulator-mounted sample is undispensible, the FOCUS PEEM can as well be properly operated without the integral sample
stage.
The requirements for a well defined field between sample and objective also implies consequences for the shape of the sample. In
order to ensure a well defined homogeneuos field, the sample surface should be as flat as possible. The flat area diameter should be at least equivalent to the front face of the objective, i.e. 5 mm,
or larger if x/y-manipulation of the sample is needed. (The opening in the objective front is about 2 mm dia.). Rough or irregularly shaped samples can also be imaged, but with restrictions for the
ultimate resolution. Since the distance between sample and objective is only about 2 mm and voltages up to 15 kV may be applied, strongly structured samples may also cause a risk of arking.
Special sample plates as for the VT STM may need to be prepared for the use in a PEEM. In this case it is necessary to mount the
samples on top of the top plate, and in addition to use a metallic shield around it. Shield and sample should form a flat surface area. A gap between sample and shield may cause distortions of the
PEEM image at the fringes of the sample area due to inhomogeneous field distributions.
Applications
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