Single- and double-slit collimating effects on fast-atom diffraction spectra

TL;DR

This study investigates how single- and double-slit collimation influence fast-atom diffraction spectra on surfaces, revealing how aperture parameters shape interference patterns and suggesting a method to probe surface potentials.

Contribution

It introduces a semi-quantum SIVR approach incorporating collimation effects and demonstrates how slit parameters affect diffraction patterns and surface potential probing.

Findings

Single-slit aperture width controls azimuthal interference patterns.

Slit length influences polar angle distribution.

Double-slit collimation can produce wide polar angle distributions.

Abstract

Diffraction patterns produced by fast He atoms grazingly impinging on a LiF(001) surface are investigated focusing on the influence of the beam collimation. Single- and double- slit collimating devices situated in front of the beam source are considered. To describe the scattering process we use the Surface Initial Value Representation (SIVR) approximation, which is a semi-quantum approach that incorporates a realistic description of the initial wave packet in terms of the collimating parameters. Our initial wave-packet model is based on the Van Cittert-Zernike theorem. For a single-slit collimation the width of the collimating aperture controls the shape of the azimuthal angle distribution, making different interference mechanisms visible, while the length of the slit affects the polar angle distribution. Additionally, we found that by means of a double-slit collimation it might be possible to obtain a wide polar angle distribution, which is associated with a large spread of the initial momentum perpendicular to the surface, derived from the uncertainty principle. It might be used as a simple way to probe the surface potential for different normal distances.