Linewidths in bound state resonances for helium scattering from Si(111)–(1 × 1)H

Abstract

Abstract. Helium-3 spin-echo measurements of resonant scattering from the Si(111)-(1x1)H surface, in the energy range 4 − 14 meV, are presented. The measurements have high energy resolution yet they reveal bound state resonance (BSR) features with uniformly broad linewidths. We show that exact quantum mechanical calculations of the elastic scattering, using the existing potential for the Helium/Si(111)-(1x1)H interaction, cannot reproduce the linewidths seen in the experiment. Further calculations rule out inelastic and other mechanisms that might give rise to losses from the elastic scattering channels. We show that corrugation in the attractive part of the atom-surface potential is the most likely origin of the experimental lineshapes.

A Helium-Surface Interaction Potential of Bi2Te3(111) from Ultrahigh-Resolution Spin-Echo Measurements

“…The blur is a measure of the average linewidth of the resonances and accounts for the fact that our purely elastic analysis with the corrugated Morse potential fails to reproduce the linewidths of the resonances as measured in the experiment. Several factors may contribute to a resonance linewidth [29] including inelasticity, disorder and the distribution of the corrugation between the attractive and repulsive parts of the potential. A comparison of the simulated data including the Gaussian blur with the experimental data ( Figure 3) shows that all main features are very well reproduced and appear at the right position in terms of ϕ and E f .…”

Diffraction of helium on MgO(100) surface calculated from first-principles

“…For this purpose a vibrational band-structure planewave program 11 was used, that solves the Schrödinger eqn (2) for the bound states within the full 3D (2D-periodic) potential. For the LMP2/Ups1 potential 5 bound states were obtained with the energies: E 0 = À7.59 meV, E 1 = À4.10 meV, E 2 = À2.05 meV, E 3 = À0.85 meV, and E 4 = À0.30 meV, all of them with an error of AE0.01 meV.…”

“…During the last two decades its usefulness has been demonstrated in the determination of numerous surface structures. [6][7][8][9][10][11] The quantitative interpretation of Hediffraction is, however, limited as the He-surface interaction potential is not known accurately. An accurate calculation of the He-surface interaction requires a quantitative description of both short range repulsive forces dominated by electronic exchange and Coulomb interactions and of the long range van der Waals interaction due to electronic correlation.…”

Helium–Surface Interaction and Electronic Corrugation of Bi2Se3(111)

“…Previous experimental studies of SARs have mainly been performed on salts with the NaCl structure, 20−26 while only recently, semimetals and semiconductors have been studied using this approach. 27−29…”