0000000000113612
AUTHOR
G.k.l Marx
A spatially resolved investigation of oxygen adsorption on polycrystalline copper and titanium by means of photoemission electron microscopy
Abstract The interaction of oxygen with polycrystalline copper and titanium surfaces was studied by means of photoemission electron microscopy. Variations in the image brightness were used to determine the work function of different Cu crystallites. The change of the work function was monitored during oxygen adsorption on both, Cu and Ti. Those changes are smooth for Cu whereas different Ti crystallites exhibit a rather complicated behavior during oxygen adsorption. The transformation of brightness versus exposure curves into work function versus coverage curves allows to determine the initial dipole moment of the adsorbed oxygen atoms. A value of about 20 mD was found for O on Cu(1 1 0). V…
Real-space observation of xenon adsorption and desorption kinetics on graphite (0001) by photoemission electron microscopy
Abstract The growth and desorption of Xe monolayers on the basal plane of graphite has been investigated by real-space imaging using photoemission electron microscopy. Adsorption kinetics was studied at different substrate temperatures (39–65 K), corresponding to different growth modes. Coexisting phases showed up as different grey values in the image. Typical domain sizes of the 2D solid phases around 60 K are of the order of one to several μm. The domains exhibit an elongated shape with their long axis oriented preferentially parallel to step edges of the substrate. With increasing coverage the brightness of the domains increases, the 2D gas-phase regions shrink and finally disappear at h…
Magneto-optical linear dichroism in threshold photoemission electron microscopy of polycrystalline Fe films.
Magnetic linear dichroism in threshold photoemission has been exploited to obtain magnetic contrast in a photoemission electron microscope using a mercury arc lamp. The dichroism at threshold can be described similar to the magneto-optical Kerr effect in the region of visible light. The asymmetry of electron intensity observed for a 100 nm polycrystalline Fe film on silicon is A=(0.37+/-0.05)%. The asymmetry occurs for the geometry of the transverse Kerr effect. For unpolarized light the asymmetry was about half the value observed for linearly polarized light. Threshold photoemission microscopy has a large potential for high resolution magnetic domain imaging with fast data acquisition.
Orbital mapping of carbon thin films by XANES-spectromicroscopy
Abstract A laterally resolved micro-XANES study (X-ray absorption near edge structure) of amorphous carbon, hydrogen terminated CVD-diamond (100) and highly oriented pyrolytic graphite (HOPG) is presented. The results were obtained by means of a photoemission electron microscope. Using this technique the well-known spectral features of carbon in its different chemical states (sp 2 , sp 3 ) could be recorded. The sp 2 /sp 3 content of the films was extracted from the spectra. Images, taken at X-ray energies corresponding to maxima (π*, C–H*) of the unoccupied density of states in these spectra, map the lateral distribution of the different orbitals at the sample surface. This study revealed …
Multipole WIEN-filter for a high-resolution X-PEEM
Abstract The development and construction of an X-PEEM with integral multipole WIEN-filter for spectromicroscopy with high lateral resolution is presented. All relevant electron-optical properties of the filter have been examined by field and trajectory calculations. Electric and magnetic multipole components (dipole, quadrupole and hexapole) can be chosen independently from each other, thus allowing electron-optical corrections. Theoretical values for the lateral resolution are in the range of 10 nm, experimental values of ≤25 nm have been achieved using the column without filter. The instrument is designed in particular for the use of Sychrotron radiation as well as new, high-brilliance l…