Fast interaction of atoms with crystal surfaces: coherent lighting

30th International Conference on Photonic, Electronic, and Atomic Collisions

Gravielle, M.S.^1

Instituto de Astronomía y Física Del Espacio (IAFE, UBA-CONICET), casilla de correo 67, sucursal 28, Buenos Aires

C1428EGA, Argentina^1

关键词: Crystallographic directions;    Fast atom diffractions;    Initial value representation;    Interference effects;    Interference mechanisms;    Interference patterns;    Interference structures;    Quantum coherence;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/875/2/012006/pdf
DOI  :  10.1088/1742-6596/875/2/012006

来源: IOP

【 摘 要 】

Quantum coherence of incident waves results essential for the observation of interference patterns in grazing incidence fast atom diffraction (FAD). In this work we investigate the influence of the impact energy and projectile mass on the transversal length of the surface area that is coherently illuminated by the atomic beam, after passing through a collimating aperture. Such a transversal coherence length controls the general features of the interference structures, being here derived by means of the Van Cittert-Zernike theorem. The coherence length is then used to build the initial coherent wave packet within the Surface Initial Value Representation (SIVR) approximation. The SIVR approach is applied to fast He and Ne atoms impinging grazingly on a LiF(001) surface along a low-indexed crystallographic direction. We found that with the same collimating setup, by varying the impact energy we would be able to control the interference mechanism that prevails in FAD patterns, switching between inter-cell and unit-cell interferences. These findings are relevant to use FAD spectra adequately as a surface analysis tool, as well as to choose the appropriate collimating scheme for the observation of interference effects in a given collision system.