Temperature dependence in fast-atom diffraction at surfaces

Abstract

Grazing incidence fast atom diffraction at crystal surface (GIFAD or FAD) have demonstrated coherent diffraction both at effective energies close to one eV ($\lambda_\perp\approx$ 14 pm) and at elevated surface...

Decoherent phonon effects in fast atom-surface scattering

“…Our analysis was based on the P0-SIVR approximation [10], which is a semiquantum method that describes the zero-phonon scattering process, including the contribution of intermediate phonon transitions. In accord with previous experimental and theoretical studies [8,[11][12][13][14], we found that the main effect introduced by FIG. 6: (Color online) Lognormal width ω of the distribution given by Eq.…”

“…While atomic projectiles elastically scattered off an ideal static surface hit the detector plane forming a thin annulus, named the Laue circle, as a consequence of the energy conservation [1,2], the inclusion of lattice vibrations within the theoretical models transforms the interference maxima into elongated streaks along the polar angle, as it is usually observed in GIFAD experiments [10][11][12][13]. Hence, the polar profile of GIFAD patterns was the focus of recent experimental and theoretical works, where the variation of the polar-profile width as a function of both, the normal incidence energy [13] and the sample's temperature [11,14], was investigated. On the other hand, a systematic theoretical study of thermal vibration effects on the azimuthal characteristics of the interference patterns as a function of the incidence conditions is still missing.…”

“…But in the vast majority of these works, diffraction patterns were assumed to be produced by elastic scattering from ideal frozen crystal surfaces, with the atoms at rest at their equilibrium positions, whereas the contribution of lattice vibrations, i.e., phonons, was considered to play a minor role, as suggested in early articles [5][6][7]. However, the influence of phonon-mediated processes on GIFAD patterns is still not fully understood, becoming a topic that has recently attracted renewed interest [8][9][10][11][12][13][14].…”

Elastic and inelastic diffraction of fast neon atoms on a LiF surface

“…The quantity E 0 θ 3 is expected to replace the binary recoil energy appearing in the standard DWF used in single scattering conditions such as X-ray, neutrons or thermal energy helium diffraction. In GIFAD, for helium projectile impinging on a LiF surface at room temperature, this 1% value of the DWF is reached with E 0 θ 3 ∼ 8–10 meV 24 while for the case of neon atoms, it is reached here between 1.1 and 1.3 meV. This is consistent with the fact that for comparable trajectory, all the binary classical energy transfers to the surface atoms should scale with the projectile mass.…”

A setup for grazing incidence fast atom diffraction

“…In this respect, a sample holder having the ability to bring the sample at elevated temperatures or to low temperatures was mandatory. In studying thermal effects in inelastic diffraction on a LiF surface we could explore temperatures between 140K and 1017K 31 where the limitation is given by the noise on the detector, probably due to electronic and ionic emission from the filament.…”