Crystalline pentacene layers can be damaged when exposed to low energy electrons. Using the Low Energy Electron Microscope this damage is researched. By analyzing the fading of the Low Energy...Show moreCrystalline pentacene layers can be damaged when exposed to low energy electrons. Using the Low Energy Electron Microscope this damage is researched. By analyzing the fading of the Low Energy Electron Diffraction (LEED) pattern of the layers the structural damage is quantified. Multiple techniques of analyzing the data are compared where a k-space filtering technique all-round gave the best results in dealing with the background. In one dataset, the height of the diffraction peaks decreases and their width broadens with increasing dose. In another dataset, the height decays exponentially and the width remains almost constant. In the data analyzed a threshold for damage to occur is found at an electron energy of around 6 eV. Damage in crystalline layers also simulated and compared to the experiments in LEEM.Show less
In the search for substrates used in the investigation of catalytic nanoparticles we have grown alumina films on NiAl(110) past 5.35 Å, the maximum thickness that can be obtained with molecular...Show moreIn the search for substrates used in the investigation of catalytic nanoparticles we have grown alumina films on NiAl(110) past 5.35 Å, the maximum thickness that can be obtained with molecular oxygen. A NiAl(110) sample was first oxidized to that thickness with molecular oxygen, after which it was stepwise oxidized with NO2. The film thickness, crystal structure and chemical composition were measured using Low Energy Electron Diffraction (LEED), X-ray Photoelectron Spectroscopy (XPS) and Scanning Tunneling Microscopy (STM). We have confirmed that film grown with NO2 follows the theoretical model of Cabrera and Mott up to 6.9 Å. STM images show an increase in the number of islands and vacancies in the metal, indicating that this growth happened at the film-metal interface and not the film surface.Show less
In this thesis we present and scrutinize a technique to reconstruct the surface profile of a sample using a low energy electron microscope (LEEM). This technique is added to the rich catalogue of...Show moreIn this thesis we present and scrutinize a technique to reconstruct the surface profile of a sample using a low energy electron microscope (LEEM). This technique is added to the rich catalogue of surface analysis techniques available in LEEM.We demonstrate that the surface profile of a sample can be deduced from the local tilt angles. This is done by studying the change in diffraction pattern. The procedure is then applied to two samples: a flake of MoTe2 that has a bump on it and a flake of MoTe2 that has collapsed into a trench. We show that we can correct for lensing effects that are introduced due to a non-flat surface. In these samples we determine the local tilt angle with an accuracy of 0.3°.Show less
