Nuclear Instruments and Methods in Physics Research B79 (1993) 381-384 North-Holland X-ray emission from multicharged ions interacting with solids S. Andriamonje LiYlil~ zyxwvutsrq B Beam Interactions with Materials A Atoms zyxwvuts Centre d’Etudes Nucliaires de Bordeaux-Grad&mm and IN2P3, Le Haut Vlgneau, F-331 75 Gradignan Cedex, France H.J. Andr$ A. Brenac, G. Lamboley, T. Lamy and A. Simionovici LAGRIPPA / CENG, BP 85& F-38041 Grenoble Cedex, France M. Bonnefoy, J.J. Bonnet, M. Chassevent and A. Fleury Laboratoire de Physique des Collisions Atom&es et Mokfculaires CNAM, 292 rue St. Martin, F-75141 Park Cedex, France Systematic studies of X-ray emission in the interaction of various slow multicharged ions (MCI) with metallic surfaces were performed at various energies. A low resolution/high efficiency Si(Li) detector and a high resolution X-ray spectrometer have been used to detect the X-ray emitted by the ions. The results allow one to differentiate between X-rays emitted from the bulk (ion bulk interaction (IBI)) and from ions experiencing an interaction above the surface (ion surface interaction (ISI)). Another example for IBI at “high” vertical velocity is the observation of two electron-one photon double K, (or K,,) emission with low energy MCI. zyxwvutsr 1. Introduction The interaction of slow multicharged ions (MCI) with solid and metallic surfaces has received consider- able attention in the past few years [l-4] with the availability of MCI sources. The attention has been centered on studies of elec- tron emission produced by MCI interacting with sur- faces. An example is the work of de Zwart [5] where the electron spectra have been interpreted by assuming an electron distribution in the various electronic shells of the atom. This interpretation is consistent with an autoionisation (AI) cascade from Rydberg levels where every electron emitted to the continuum is immediately replaced by a new resonantly transferred electron from the surface. Using a Ge X-ray detector, Donets [6,7] for the first time observed the X-ray emission of Ar”+ impinging at 17 keV on a Be target, which has been interpreted as arising from an electron distribution at the moment of the X-ray emission [8] which is not compatible with the AI-cascade model. This interpretation has been confirmed by the analysis of Andrl et al. [4] and the recent results of Briand et al. [9]. In order to understand this difference between the results obtained with the electron emission and X-ray emission from MCI interacting with’surfaces, we have performed a series of experiments. Three experimental methods have been used: i) a low resolution but high efficiency Si(Li) X-ray detector has been used for sys- tematic studies of X-ray emission from MCI as a func- tion of Gin, the angle of incidence with respect to the surface plane; ii) a high resolution crystal spectrometer has been used to resolve the different contributions to the K, satellites; and iii) use of decelerated MCI to eliminate the principal contribution of IBI. 2. Experimental methods MCIs of Ne’+, Ne”+, and Arl’+ from the LA- GRIPPA facility [lo] have been impinging in its second diagnostics chamber on targets of amorphous Ta and C and doped monocrystalline Si at a vacuum of 10e5 Pa. The X-rays emitted in the interaction between MCI and these targets have been detected by: - A Si(Li) detector with a resolution of 170 eV at 5.9 keV but with high efficiency for the low resolution studies. The energy calibration has been obtained from 55Fe and ‘@Cd standard X-ray sources. Gaussian fits to the Mn K X-rays emitted by the s5Fe source and to the Ag L X-rays emitted by the “‘Cd source yielded calibration points around 6 and 3 keV. They allowed an absolute calibration of the X-rays emitted by the Arl’+ interacting with solids. The detector with a useful area of 70 mm* and with a Be window of 25 pm has been placed at 90” with respect to the beam direc- tion. - A Bragg spectrometer [ll] supplied with a flat RbAP (and/or a beryl) crystal for high resolution 0168-583X/93/$06.00 0 1993 - Elsevier Science Publishers B.V All rights reserved VII. PIXE, MICROPROBES, .