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People Dr. Hugo Ascolani Dr. Oscar Grizzi Dr. Esteban A. Sánchez Dr. Guillermo Zampieri Dra. María L. Martiarena Dr. Víctor H. Ponce Dr. Julio E. Gayone (postdoc) Lic. Silvina Bengió (PhD student) Lic. L. De Ferrariis (PhD student) Gonzalo Otero (student).
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People Dr. Hugo Ascolani Dr. Oscar Grizzi Dr. Esteban A. Sánchez Dr. Guillermo Zampieri Dra. María L. Martiarena Dr. Víctor H. Ponce Dr. Julio E. Gayone (postdoc) Lic. Silvina Bengió (PhD student) Lic. L. De Ferrariis (PhD student) Gonzalo Otero (student) Publications: 60 in international journals (since 1996) Invited talks: 10 (since 1996) PhD thesis: 8 (since 1987) Budget: $250,000 (since 1996) Surface Physics Research at the Centro Atómico Bariloche (since 1987 to 2001)
Intrinsic properties of materials • Characterization of surfaces by ion scattering • Characterization of surfaces by photoemission • Electronic properties of perovskites • Characterization of hard amorphous carbon films. Surface Characterization by TOF-ISSG. Otero, J.E. Gayone, E.A. Sánchez, O. GrizziCollaboration with Surface Physics Group of Santa Fe (INTEC) - Argentina • Surface Reconstruction • Adsorption Kinetics • Adsorption sites • Thin film growth • Charge exchange • Interaction of electrons and ions with surfaces. • Excitation of phonons in medium-energy electron spectroscopies. • Inelastic processes in ion-surface collisions • Modifications of surfaces by ion bombardment
Intrinsic properties of materials • Characterization of surfaces by ion scattering • Characterization of surfaces by photoemission • Electronic properties of perovskites • Characterization of hard amorphous carbon films. Atom and molecule adsorption on semiconductor surfaces Silvina Bengió and Hugo Ascolani Collaboration: M.C. Asensio, spanish-french beam-line at LURE, Orsay, France. • Adsorption site of the OH radicals in the H2O/Si(100) system. • Electronic Structure of Ga/Si(111). • Order-disorder phase transition of the Sn/Ge(111) system. • Photoemission and syncrhotron radiation • Estructural properties: Photoelectron diffraction • Chemical and electronic properties: XPS and ARUPS Adsorption of H2O on Si(100) • Interaction of electrons and ions with surfaces. • Excitation of phonons in medium-energy electron spectroscopies. • Inelastic processes in ion-surface collisions • Modifications of surfaces by ion bombardment Photoelectron diffraction
Intrinsic properties of materials • Characterization of surfaces by ion scattering • Characterization of surfaces by photoemission • Electronic properties of perovskites • Characterization of hard amorphous carbon films. Electronic Structure of Transition-Metal Perovskites.G. Zampieri, J.E. Gayone.Collaboration: Dr M. Abbate, Laboratorio Nacional de Luz Sincrotron, Campinas, (Brazil) CAB-Bariloche, Argentina Study of occupied and unoccupied electron densities of states with XPS, UPS and XAS Studied Systems: Sr2FeMoO6, LaNiO3-x (0<x<0.5), CaMnO3-x (0<x<0.5), LaMnO3+y (0<y<0.15), SrFe1-xCoxO3. • Interaction of electrons and ions with surfaces. • Excitation of phonons in medium-energy electron spectroscopies. • Inelastic processes in ion-surface collisions • Modifications of surfaces by ion bombardment XPS: Valences of Fe and Mo in Sr2FeMoO6
Intrinsic properties of materials • Characterization of surfaces by ion scattering • Characterization of surfaces by photoemission • Electronic properties of perovskites • Characterization of hard amorphous carbon films. Excitation of Phonons in Medium-Energy Electron Spectroscopies. H. Ascolani, G. Zampieri, J.E. Gayone.Collaboration: Dr. Ph. Hofmann, Institute for Storage Ring Facilities, University of Aarhus, Aarhus, Denmark • Experimental and theoretical study of the excitation/absorption of phonons in: • LEED-MEED • Valence-band photoemission. The angular pattern changes as the wave vector conservation rules are gradually relaxed by the excitation/absorption of phonons. LEED-MEED Transition Valence Band Photoemission from Al(100) • Interaction of electrons and ions with surfaces. • Excitation of phonons in medium-energy electron spectroscopies. • Inelastic processes in ion-surface collisions • Modifications of surfaces by ion bombardment LEED MEED
Intrinsic properties of materials • Characterization of surfaces by ion scattering • Characterization of surfaces by photoemission • Electronic properties of perovskites • Characterization of hard amorphous carbon films. Electron emission in grazing ion-surface collisions E.A. Sánchez, O. Grizzi and G. Otero Collaboration with LCAM-Orsay, France Effect of surface induced- and track- potentials • Inelastic processes: • Convoy electrons • Auger electron emission • Projectile autoionization • Plasmonexcitation and decay. • Interaction of electrons and ions with surfaces. • Excitation of phonons in medium-energy electron spectroscopies. • Inelastic processes in ion-surface collisions • Modifications of surfaces by ion bombardment Effect of the surface topography
2 F (y,z) • Intrinsic properties of materials • Characterization of surfaces by ion scattering • Characterization of surfaces by photoemission • Electronic properties of perovskites • Characterization of hard amorphous carbon films. Theoretical studies of electron emission in grazing ion-surface collisionsM.L. Martiarena and V.H.Ponce. • Surface ionization by ion impact • Binary - electron production • Convoy electron emission Continuum wave of an hydrogen atom in front of metallic surfaces • Interaction of electrons and ions with surfaces. • Excitation of phonons in medium-energy electron spectroscopies. • Inelastic processes in ion-surface collisions • Modifications of surfaces by ion bombardment k,m=0
Intrinsic properties of materials • Characterization of surfaces by ion scattering • Characterization of surfaces by photoemission • Electronic properties of perovskites • Characterization of hard amorphous carbon films. Modification of surfaces by ion bombardment E.A. Sánchez and G. Otero Collaboration with CAB-Bariloche, Argentina Roughening of flat semiconductor surfaces by Blistering and Sputtering Swelling • Interaction of electrons and ions with surfaces. • Excitation of phonons in medium-energy electron spectroscopies. • Inelastic processes in ion-surface collisions • Modifications of surfaces by ion bombardment Flattening of rough metal surfaces by Sputtering Phase transformation in alloys Cu-Zn-Al(100) Mechanically polished After grazing bombardment 6.5 dpa (3 x 1015 ions/cm2), 30 keV Ar