PHOTON SCIENCE

The HAXPEEM is operated in collaboration with the group of Claus Schneider from Research Center Jülich. Please contact beam line staff prior to proposal submission!

In order to resolve lateral structures on the sub-μm scale in combination with HAXPES, a HAXPEEM instrument has been developed and commissioned at beamline P09 by the Team of C. M. Schneider (Research Center Jülich, Germany). The HAXPEEM instrument is a Focus NanoESCA modified for higher excitation energies.

In this type of energy-filtering photoemission microscope, an immersion lens objective collects photoelectrons from the sample and forms a first real image. A tetrode lens electrostatic transfer optic retards the electrons and feeds the image into the entrance of a 125 mm hemispherical analyzer operating at constant pass energy. A variable aperture located in the analyzer exit plane defines the transmitted energy bandwidth. After passing a second symmetric hemisphere to cancel image aberrations, the image is recovered and a two-stage projector optics delivers a final total magnification of up to ~1500×. The photoelectron image is then intensified by a double MCP stack and converted into a visible image by a fluorescence screen. To expand the range of kinetic energies up to 10 keV, the potentials of the objective lens, including the sample, have been scaled up and the insulation improved accordingly. The standard operation voltage for the extractor electrode of the immersion lens is 24 kV, and a maximum of 30 kV is possible. The sample voltage can be swept up to 10 kV, which defines the range of kinetic energies up to 10 keV. The instrument can accept flat, conductive samples of size 10 × 10 mm2 and 1 mm thickness and has a storage stage for up to four samples for quick exchange.