Open AccessOn space charge effects in laboratory-based photoemission electron microscopy using compact gas discharge extreme ultraviolet sources
Author(s) -
Daniel W. Wilson,
Christoph Schmitz,
Denis Rudolf,
C. Wiemann,
Claus M. Schneider,
Larissa Juschkin
Publication year - 2020
Publication title -
new journal of physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.584
H-Index - 190
ISSN - 1367-2630
DOI - 10.1088/1367-2630/abbc29
Subject(s) - physics , extreme ultraviolet , photoelectric effect , photoemission spectroscopy , electron , synchrotron radiation , atomic physics , space charge , photon energy , inverse photoemission spectroscopy , optics , x ray photoelectron spectroscopy , photon , laser , nuclear magnetic resonance , quantum mechanics
The analysis of electronic and structural properties of surfaces has been greatly advanced by photoemission electron microscopy and spectroscopy techniques. To further improve lateral and energy resolution of the instruments, it is necessary to optimize parameters of the radiation sources employed for photoemission studies (e.g. photon flux, pulse duration, spot size etc). We studied space charge effects observed in an energy-filtering photoemission electron microscope operated with a compact laboratory-scale gas-discharge extreme ultraviolet light source. In this system, we found limits of spatial- and energy-resolution controlled by the source radiation parameters. The pulse repetition rate can be varied in the kHz range and the duration of the EUV emission was measured to be several tens of nanoseconds long, and thereby very different from the standard synchrotron sources typically used for similar experiments. The spatial resolution could be improved by a factor of 5, but only on the expense of the photon density per pulse, which had to be decreased by a factor of 17 in order to reduce the image blur due to space charge effects. Furthermore, we found broadening of the x-ray photoelectron spectroscopy peaks for high photon fluxes. We have also performed a n -body Monte Carlo simulation to evaluate the difference between core-level photoelectrons and secondary electrons with respect to space charge.