Review of Scientific Instruments

Chopped sample heating for quantitative profile analysis of low energy electron diffraction spots at high temperatures

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Spot profile analysis low energy electron diffraction (SPA-LEED) is one of the most versatile and powerful methods for the determination of the structure and morphology of surfaces even at elevated temperatures. In setups where the sample is heated directly by an electric current, the resolution of the diffraction images at higher temperatures can be heavily degraded due to the inhomogeneous electric and magnetic fields around the sample. Here we present an easily applicable modification of the common data acquisition hardware of the SPA-LEED, which enables the system to work in a pulsed heating mode: Instead of heating the sample with a constant current, a square wave is used and electron counting is only performed when the current through the sample vanishes. Thus, undistorted diffration images can be acquired at high temperatures. © 2004 American Institute of Physics.