AODO: Secondary ion emission and surface modification S. Akcöltekin a , I. Alzaher b , B. Ban d’Etat b , T. Been b , P. Boduch b , A. Cassimi b , H. Hijazi b , H. Lebius b , B. Manil b , J.M. Ramillon b , H. Rothard b, * , M. Schleberger a , E.F. da Silveira c a FB Physik, Universität Duisburg-Essen, 47048 Duisburg, Germany b Centre de Recherche sur les Ions, les Matériaux et la Photonique CIMAP, CEA-CNRS UMR 6252-ENSICAEN-Université de Caen-Basse Normandie, CIMAP-CIRIL-Ganil, BP 5133, Boulevard Henri Becquerel, F-14070 Caen Cedex 05, France c Pontifícia Universidade Católica PUC, Departamento de Física, Rua Marques de São Vicente 225, Gávea, 22453-900 Rio de Janeiro, Brazil article info Article history: Received 6 October 2008 Received in revised form 5 November 2008 Available online 27 November 2008 PACS: 79.20.Rf 34.50.+q 61.80.Jh Keywords: Sputtering Highly charged ions Surface structure LEED abstract In order to study the sputtering of secondary ions from well characterized surfaces, we constructed a new UHV system named AODO. It consists of a detector chamber, a target preparation and analysis chamber, and a target transfer rod. We present the lay-out of this new instrument. The detector allows measuring the time-of-flight of emitted secondary ions and their position on a 2D imaging detector (XY-TOF imaging technique). The analysis chamber can be used to study surface modification by means of LEED (low energy electron diffraction). We show preliminary results of the evolution of the LEED patterns as a func- tion of the projectile fluence during irradiation of HOPG (highly oriented pyrolytic graphite) with slow Xe 14+ ions at ARIBE (the low energy, highly charged ion beam line of the French heavy ion accelerator GANIL). Ó 2008 Elsevier B.V. All rights reserved. 1. Introduction The impact of ions on solid surfaces may lead to surface modi- fication (single ion tracks at low fluences, structural transformation at high fluences) [1,2]. Furthermore, sputtering of atoms or mole- cules from the surface occurs [3]. Thus, studying the induced ef- fects on the surface by techniques such as AFM (‘‘atomic force microscopy”) [4] or LEED (‘‘low energy electron diffraction”) on the one hand, and of sputtered particles (neutrals, secondary ions) [5,6] on the other hand yields valuable and complementary infor- mation about energy deposition and damage creation in irradiated solids. Different mechanisms can lead to sputtering: elastic collisions (target nuclei, ‘‘nuclear stopping”), inelastic collisions (target elec- trons, ‘‘electronic stopping”) and ‘‘potential sputtering” with highly charged ions. The different facilities of the French heavy ion accel- erator GANIL (‘‘grand accélérateur national d’ions lourds”), like e.g. the medium energy beam line SME (‘‘sortie moyenne énergie”) and the low energy, highly charged ion beam line ARIBE (‘‘accélérateurs pour les recherches avec les ions de basse énergie”), cover a wide range of heavy multiply charged ion energies (from, say 50 keV to 1 GeV). Thus, they offer the unique possibility to study the con- tribution of the different physical mechanisms of energy deposi- tion to surface modification and sputtering. For example, angular distributions of emitted neutrals (catcher technique) [7,8] or sec- ondary ion mass spectra (‘‘time-of-flight” TOF) of sputtered parti- cles from uranium dioxide (UO 2 ) both at high energy in the electronic stopping regime (MeV/u) and with very low energy highly charged ions (q keV) [7,9] were performed at GANIL. We constructed a new UHV system named AODO for investigat- ing the sputtering of secondary ions from well defined surfaces as well as ion induced modifications (Fig. 1). It consists of (1) an irra- diation chamber with an XY-TOF ion detector, (2) a target prepara- tion and analysis chamber and (3) a target transfer rod. The set-up allows measuring the time-of-flight of emitted secondary ions and their position on a 2D imaging detector (XY-TOF imaging tech- nique). The analysis chamber can also be used to study surface modification by means of LEED and AES (‘‘Auger electron spectroscopy”). 2. Sputtering of secondary ions: XY-TOF technique The AODO set-up can be used at the different beam lines of GA- NIL as well as at other accelerator facilities. The experimental set- up for the measurement of the complete secondary ion velocity 0168-583X/$ - see front matter Ó 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.nimb.2008.11.018 * Corresponding author. E-mail address: rothard@ganil.fr (H. Rothard). Nuclear Instruments and Methods in Physics Research B 267 (2009) 649–651 Contents lists available at ScienceDirect Nuclear Instruments and Methods in Physics Research B journal homepage: www.elsevier.com/locate/nimb