Berlin 2018 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 77: Poster: Plasmonics and Nanooptics

O 77.22: Poster

Mittwoch, 14. März 2018, 18:15–20:30, Poster A

Improved Dynamic Range Imaging in Time-Resolved 2PPE PEEM — •David Janoschka, Pascal Dreher, Michael Horn - von Hoegen, and Frank Meyer zu Heringdorf — Faculty of Physics and Center for Nanointegration (CENIDE), University of Duisburg-Essen, Duisburg, Germany

The commonly used detector for low energy electron microscopy (LEEM) or photoemission electron microscopy (PEEM) is a combination of a multichannel plate (MCP) with a phosphor screen. An optical CCD or CMOS camera is then used to film the microscope image off the screen. In time-resolved imaging of nonlinear electron emission from strong plasmonic fields (Plasmoemission) such detection scheme reaches its limitations due to the high contrast and the dramatic intensity variations in the data on a sub-micrometer scale: simply due to the construction of a MCP/Screen combination, every bright small emission spot on the MCP is surrounded by a disc of slightly increased intensity ("halo"), which makes a quantitative analysis of the electron yield between two bright emission spots almost impossible. On the poster we report on a recent upgrade of the SPE-LEEM microscope at the University of Duisburg-Essen, during which the MCP/screen combination was replaced with a fiber-coupled CMOS sensor. We will show PEEM and LEEM images obtained with the new detector and we will compare the performance of the new detector with the previously used MCP setup. The new detector provides us with a much higher dynamic range, with less noise, and imaging without halos.