Comment on "Quantum Scattering of Heavy Particles from a 10 K Cu(111) Surface"

TL;DR

This paper critiques previous experimental interpretations of atom-surface scattering data, arguing that the original experiments were conducted in a quantum regime where semiclassical models are invalid, thus questioning prior conclusions.

Contribution

It provides a critical analysis of earlier experimental data, emphasizing the importance of quantum effects in atom-surface scattering at various temperatures.

Findings

Quantum scattering regime dominates the experiments

Semiclassical Debye-Waller factor deviates from quantum predictions

Previous interpretations may be invalid in quantum regime

Abstract

In the original paper Althoff et al. (see ibid., vol.79, p.4429 (1997)) reported a study of scattering of thermal Ne, Ar, and Kr atoms from a Cu(111) surface in which they assessed the corresponding Debye-Waller factor (DWF) as a function of the particle mass m in a wide range of substrate temperature T. The experiments were interpreted by the semiclassical DWF theory in which the projectile moves on the classical recoilless trajectory and the surface vibrations are quantized. Siber and Gumhalter claim that the experiments described by Althoff et al. were carried out in the quantum scattering regime in which the semiclassical scalings of Althoff et al. do not hold and the semiclassical DWE significantly deviates from the exact quantum one both in the low and high T limits. Hence, it is claimed, the quantum scattering data of Althoff et al. cannot be reliably interpreted by the semiclassical theory.