Comparative analysis of the low-energy He  ions scattering on Al and Al 2 O 3 surfaces V.M. Fomin a, * , V.R. Misko a,1 , J.T. Devreese a,2 , H.H. Brongersma b a Theoretische Fysica van de Vaste Stof, Departement Natuurkunde, Universiteit Antwerpen (UIA), Universiteitsplein 1, B-2610 Antwerpen, Belgium b Faculty of Physics and Schuit Institute of Catalysis, Technische Universiteit Eindhoven, P.O. Box 513, NL-5600 MB Eindhoven, The Netherlands Received 16 June 1998; received in revised form 28 July 1998 Abstract Using the Anderson±Muda±Newns approach, the neutralization rate and the ion survival probability have been calculated for the large angle scattering of low-energy He  ions by Al and by Al 2 O 3 . The two-band model of the electronic energy spectra is applied for the case of alumina. The electron promotion has been shown to play an im- portant role in the processes of the He  ions scattering by aluminum and alumina. The experimentally observed absence of the matrix eect is discussed on the basis of the obtained results. Ó 1998 Elsevier Science B.V. All rights reserved. PACS: 34.50.Dy; 34.70.+e; 79.20.Rf Keywords: Atomic and ion beam interactions with surfaces; Ion neutralization; Ionization by collision 1. Introduction Low-energy ion scattering (LEIS) has been demonstrated to be a sensitive technique for the quantitative analysis of the composition of the outermost atomic layer of a target, see e.g. Refs. [1±3] and references therein. The scattered ion signal depends both on the dierential scattering cross section and on the ion fraction (number of ions scattered in a given direction divided by the total number of particles scattered into that di- rection). Since for large angle scattering small ion± atom separations are relevant, the scattering Nuclear Instruments and Methods in Physics Research B 145 (1998) 545±552 * Corresponding author. Permanent address: Department of Theoretical Physics, State University of Moldova, Str. A. Mateevici 60, MD-2009 Kishinev, Republic of Moldova. Also at: Technische Universiteit Eindhoven, P. O. Box 513, 5600 MB Eindhoven, The Netherlands. Tel.: 00 32 3 8202460; fax: 00 32 3 8202245; e-mail: fomin@uia.ua.ac.be 1 Visiting Postdoctoral Fellow of FWO-V. Permanent address: Department of Theory of Semiconductors and Quan- tum Electronics, Institute of Applied Physics, Academy of Sciences of Moldova, Str. Academiei 5, MD-2028 Kishinev, Republic of Moldova. 2 Also at: Universiteit Antwerpen (RUCA), Groenenbor- gerlaan 171, B-2020 Antwerpen, Belgium and Technische Universiteit Eindhoven, P. O. Box 513, 5600 MB Eindhoven, The Netherlands. 0168-583X/98/$ ± see front matter Ó 1998 Elsevier Science B.V. All rights reserved. PII: S 0 1 6 8 - 5 8 3 X ( 9 8 ) 0 0 5 3 0 - 8