Quantum scattering of neon from a nanotextured surface

Levi, A.C., Huang, C., Allison, W. and MacLaren, D.A. (2009) Quantum scattering of neon from a nanotextured surface. Journal of Physics: Condensed Matter, 21(22), (doi: 10.1088/0953-8984/21/22/225009)

Abstract

Phonon exchange is the usual cause of decoherence in atom–surface scattering. By including quantum effects in the treatment of Debye–Waller scattering, we show that phonon exchange becomes ineffective when the relevant phonon frequencies are high. The result explains the surprising observation of strong elastic scattering of Ne from a Cu(100) surface nanotextured with a c(2 × 2) Li adsorbate structure. We extend a previous model to describe the phonon spectra by an Einstein oscillator component with an admixture of a Debye spectrum. The Einstein oscillator represents the dominant, high frequency vibration of the adsorbate, normal to the surface, while the Debye spectrum represents the substrate contribution. Neon scattering is so slow that exciting the adsorbate mode has a low probability and is impossible if the incident energy is below the threshold. Thus, adsorbate vibrations are averaged out. A theoretical discussion and calculation shows that under such circumstances the vibrations of a light adsorbate do not contribute to the Debye–Waller effect, with the result that Ne scattering at thermal energies is quantum mechanical and largely elastic, explaining the high reflectivity and the diffraction peaks observed experimentally.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: MacLaren, Professor Donald
• Authors: Levi, A.C., Huang, C., Allison, W., and MacLaren, D.A.
• Subjects: Q Science > QC Physics
• College/School: College of Science and Engineering > School of Physics and Astronomy
• Journal Name: Journal of Physics: Condensed Matter
• Publisher: Institute of Physics Publishing Ltd.
• ISSN: 0953-8984
• ISSN (Online): 1361-648X
• Copyright Holders: Copyright © 2009 IOP Publishing Ltd
• First Published: First published in Journal of Physics Condensed Matter 21(22)
• Publisher Policy: Reproduced in accordance with the copyright policy of the publisher.