Collective Diffusion on Surfaces: Correlation Effects and Adatom Interactions ASeriespresentingtheresultsofscientificmeetingssupportedundertheNATOScience Programme. TheSeriesispublishedbylOSPress,Amsterdam,andKluwerAcademicPublishersinconjunction withtheNATOScientificAffairsDivision Sub-Series I. LifeandBehaviouralSciences lOSPress II. Mathematics,PhysicsandChemistry KluwerAcademicPublishers III.ComputerandSystemsScience lOSPress IV.EarthandEnvironmentalSciences KluwerAcademicPublishers TheNATOScienceSeriescontinuestheseriesofbookspublishedformerlyastheNATOASISeries. The NATOScience Programmeofferssupportforcollaborationincivilsciencebetweenscientistsof countriesoftheEuro-AtlanticPartnershipCouncil.Thetypesofscientificmeetinggenerallysupported are"AdvancedStudyInstitutes"and"AdvancedResearchWorkshops",andtheNATOScienceSeries collects together the results of these meetings.The meetings are co-organized bijscientists from NATOcountriesandscientistsfrom NATO'sPartnercountries- countriesoftheCISandCentraland EasternEurope. AdvancedStudyInstitutesarehigh-leveltutorialcoursesofferingin-depthstudyoflatestadvances inafield. Advanced ResearchWorkshopsare expert meetingsaimedatcriticalassessmentofafield, and identificationofdirectionsforfutureaction. AsaconsequenceoftherestructuringoftheNATOScienceProgrammein1999,theNATOScience Serieswasre-organizedtothefoursub-seriesnotedabove.Pleaseconsultthefollowingwebsitesfor informationonpreviousvolumespublishedintheSeries. http://www.nato.inVscience http://www.wkap.nl http://www.iospress.nl http://www.wtv-books.de/nato-pco.htm riesII:Mathematics,PhysicsandChemistry- Vol.29 Collective Diffusion on Surfaces: Correlation Effects and Adatom Interactions edited by M.C. Tringides Department of Physics and Astronomy, Iowa State University, Ames, Iowa, U.SA and z. Chvoj Institute of Physics, Academy of Sciences of the Czech Republic, Prague, Czech Republic Springer Science+Business Media, B.V. Proceedings of the NATO Advanced Research Workshop on Collective Diffusion on Surfaces: Correlation Effects and Adatom Interactions prague, Czech Republic 2-6 October 2000 A C.I.P. Catalogue record for this book is available from the Library of Congress. ISBN 978-0-7923-7116-8 ISBN 978-94-010-0816-7 (eBook) DOI 10.1007/978-94-010-0816-7 Printed on acid-free paper AII Rights Reserved © 2001 Springer Science+Business Media Dordrecht Originally published by Kluwer Academic Publishers in 2001 Softcover reprint of the hardcover 1 st edition 2001 No part of the material protected by this copyright notice may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording or by any information storage and retrieval system, without written permission from the copyright owner. TABLE OF CONTENTS Preface. ix I. Surface Diffusion atEquilibrium QuasielasticHeliumScatteringStudiesofSurfaceDiffusion: TheDiffusionBarrier . .. A. P.GrahamandJ. P.Toennies ExperimentalAspectsofMetalParticleDiffusiononaSiliconSurface 11 JiriSlezak, PavelSchukrinov,Alexei Savchenkov, PingoMutombo, andVladimirChab SurfaceDynamicsofSteppedSi(001)Studied byTemporalLEED Spectroscopy . 23 K. Kammler, M. HornVon Hogen, N.Voss, M.Tringides, A. Menzel, andE. H. Conrad ElectricCurrentInducedAsymmetryofSurfaceDiffusion-Instabilityof VicinalCrystalSurfaces . 33 S. S. Stoyanov, J. J.Metois,andV. Tonchev MemoryEffectsandMemoryFunctionsinSurfaceDiffusion 47 T. Hjelt, E. Kuusela, J. M. Lahtinen,T. Ala-Nissila, I.Vattulainen,and S. C. Ying Driven DiffusioninaModeloftheOIW(110)System . 59 M.A. Zaluska-Kotur, StanislawKrukowski, and LukaszA. Turski SurfaceDiffusionandReal-SpaceRenormalizationGroup .. 71 A. A. Tarasenko, L. Jastrabik, F. Nieto,andC. Uebing SurfaceDiffusion NearPhaseTransitions . 83 F. Nieto,A. Tarasenko,andC. Uebing II. Surface Diffusionfrom ProfileEvolution Methods SurfaceHeterodiffusioninAdsorbedandCoadsorbedOverlayersofLi, Sr, andCuontheWandMo(112)Surfaces ...... 97 A. T. Loburets, N. B. Senenko,Yu. S. Vedula, andA. G. Naumovets MetalHeterodiffusionon MetallicSurfaces: CaseofPbonCu 107 C. Cohen, G. Prevot, and D. Schmaus StepEffectsonSurfaceDiffusion: AComprehensiveStudyofCOon Pt(111) 117 XudongXiao Adsorption, Desorption,andDiffusionofPotassiumon MetalandOxide Surfaces 129 G. Kerner, I.M. Danziger,W. Zhao,andM.Asscher III. Surface DiffusionUnderNon-equilibriumConditions DynamicsofInteractingAdparticlesUnderNon-EquilibriumConditions .. 143 Z.Chvoj vi Statistical-MechanicalDescriptionofNonequilibriumProcessesinInteracting LatticeGases . 157 V. S.Vikhrenko,G. S. Bokun,andVa.G.Groda ModelStudiesofCollectiveDiffusion .. 169 I.Vattulainen StudyofNon-EquilibriumSurfaceDiffusion FromanInitialStep-Concentration ProfileWithaNewProbability-BasedContinuumMethod 179 M. R. DudekandM. C.Tringides IV. Diffusion MechanismsinGrowthProcesses DiffusiononandINSurfaces: TheAtomicSlidePuzzle . 191 J.W. M. Frenken, R.VanGastel, S. B.VanAlbada, E. Somfai, andW. VanSaarloos DecayofTwo-DimensionalIslandsonAg(110) . 201 K. Morgenstern, E. Leegsgaard,andF. Besenbacher SurfaceMorphologyanddynamics: UsingAb-initioTotalEnergiestomakethe MostoftheSTMData . 213 PeterJ. Feibelman Substrate-MediatedInteractiononAg(111)SurfacesFromFirstPrinciples .. 225 KristenA. FichthornandMatthiasScheffler DiffusionofAdatomsandSmallClustersonMissing-Row-Reconstructed Surfaces..................................................... 237 F. MontalentiandR. Ferrando EffectsofAdsorbatesonSubmonolayerGrowth 247 MiroslavKotrla, JoachimKrug, andPavel$milauer SUrfactantsinSemiconductorHeteroepitaxy: Thermodynamicsand/orkinetics? ........ 259 IvanMarkov V. SubstrateEffectsand Surface Diffusion NonlinearDiffusionandSliding Friction . 273 S. C. Ying, E.Granato,andT.Ala-Nissila SelectiveActivationDynamics: AMinimalPathApproach............................................ 285 L. Y.Chen, P. L. Nash,andS. C. Ying LongJumpsinSurfaceDiffusionInvestigatedbyStochasticEquations .. 295 R. Ferrando, R. Spadacini,andG. E.Tommei AnalyticalKineticTheoryofSingle-ParticleandCollectiveSurface Diffusion . 305 S. Yu. Krylov AdatomIslandDiffusiononMetalFCC(100)Surfaces 317 O. S.Trushin, J. Hirvonen, J. Heinonen,P. Salo, M.Alatalo, T.Ala-Nissila, I. Koponen, andJ.Merikoski Paths, Barriers,andPrefactorsforAdatomDescentfromAgClustersonAg(111) 327 T. S. Rahman, A. Kara,A. Karim, A. AI-Rawi vii CorrelatedDiffusionofAdatomsand IslandsontheLowIndexedSurfacesofNoble MetalsandAlloys . .. 339 A. E. Evangelakis AuthorIndex . 351 SubjectIndex .. 353 Preface As materials research focuses into finding ways to control the growth of atomic scale structures, there is correspondingly increasing emphasis on to the problem of surface diffusion. Clearly surface diffusion is the key process, which determines how atoms move on the surface. Controlling this motion can lead to the easy fabrication of well-controlled nanostructures broadening the present possibilities in nanotechnology. The paradigm ofsurface diffusion has outgrown its standard textbook description as a random walk on a rigid substrate. In real systems for more complex situations are encountered: interacting atoms are commonly present on the surfacewith their motions highly correlated, different phases form on the surface with different dynamics, large concentration gradients drive the system far away from the linear response regime, rich metastable structures form as a result of balanced interplay between different kinetic processes, substrate relaxation can change the energy landscape and thediffusion barriers, etc. The motivation behind this ARW was to bring together the international community working on these problems. We felt that the large number of researchers, new results, and well-formulated open questions in this area require some form of integration in a single forum. The ARW and the upcoming proceedings book with papers by the majority of the participants has provided thisforum. The meeting was not planned as a continuation of the earlier NATO ASI in Rhodes in 1996, although several people have participated in both meetings. The goal ofthe Rhodes meeting was to bring together workers on the atomistic aspects of surface diffusion with workers on many-body, collective effects to initiate a dialogue between the two groups. The Prague meeting has concentrated more on the latter. The meeting was held in the beautiful city of Prague, which offers an unparallel combination of physical beauty, historical treasures, cultural life, and cosmopolitan spirit. After the rigor of the scientific lectures, it was relaxing to stroll along the banks ofthe river Vltava orto climb up the unending steps to the top ofthe castle to be rewarded with the panoramic view ofthe city. Maybe the only uncooperative element was the weather, to ensure that the experience was real. It is impossible in the short preface to give justice to the excitement of the presentations and discussions ofthe meeting. The excitement can be found by reading the chapters that follow. We are limited in simply making a general observation that we believe is shared by most practitioners in the field: how the gap between theory and experiment is narrowing. This narrowing between theory and experimentcan be seen from several advances. Realisticsimulations ix x of complicated physical phenomena can include many competitive microscopic processes over longer time scales; analytic methods have been developed to describe surfacediffusion infar-fram-equilibrium experiments; the behaviorofthe diffusion coefficientcloseto aphasetransition hasbeen predicted and measured in similar systems; new experimental methods can probe the system close to equilibriumtotestfundamental predictionsofstatistical mechanics. The success ofthe meeting is a result ofthe hard work ofseveral people. We would liketofirstthankthe members ofthe Organizing Committee (ProfessorsV. Chab and R. Ferrando) who have been full of ideas about the scientific and social program. The meeting would not have run so smoothly without the dedicated commitment of the student support (M. Ma_in, H. Chvojova, P.Jelinek). The professionalism and expertise ofthe veteran of several NATO meetings, Rebecca Shivvers, is greatly appreciated for the high quality of the proceedings volume. The great hospitality displayed by the Czech people involved with the meeting (both scientists and non-scientists) has flooded the meeting with unbounded warmth and care. Ofcourse, nomeeting ispossiblewithoutgenerousfinancial support. We greatly thank the NATO Scientific Division for providing us the majority ofthe funds for the meeting, in their tradition of supporting so many high quality scientific meetings year-afier-year. We thank the support of the Czech Academy of Science and the Helsinki Institute ofTechnology, which have offered additional financial support to cover the cost of the facilities and support student participation. We believe the meeting has catalyzed the formation of a cohesive cluster of scientists working on the collective aspects of surface diffusion. The strong interactions between the participants displayed at the meeting proves that the cluster is highly stable beyond critical size. Future meetings to follow-up on the goals and vision ofthe Prague meeting should beanticipated. Ames and Prague, March 2001. QUASIELASTIC HELIUM SCATTERING STUDIES OF SURFACE DIFFUSION: THE DIFFUSION BARRIER A. P. GRAHAMl AND J. P. TOENNIES2 Max-Planck Insitut fiir Stromungsforschung, Bunsenstrafte 10, D-37073 Gottingen, Germany Abstract. Some results of recent quasielastic helium scattering (QHAS) on the surface diffusionofadatoms and adsorbates are reviewed. Particular emphasis is placed on the evaluation ofthe effective diffusion barrier ener gies measured and their dependenceon the system and temperature range. 1. Introduction During the last 12 years, improvements in the helium atom scattering (HAS) method, particularly in resolution, intensity, and stability, have per mitted the quasielastic broadening of the elastic peak due to adsorbate diffusion to be determined with high accuracy and reliability [1]. The de pendence ofthe quasielastic widthon momentum transfer (or wave vector) and temperature have, typically, beenanalyzed usinganalogies toquasielas tic neutronscattering (QNS) [2], enablingthe diffusionofa large numberof adsorbatejadatom-substrate systems to be measured [1, 3]. With only two exceptions, namely PbjPb(llO) [4] and NijNi(llO) [1], the effective dif fusion barriers obtained with quasielastic helium atom scattering (QHAS) have been significantly lower than anticipated, prompting speculation that the QHAS results have been incorrectly interpreted [5]. Consequently, it is appropriate to discuss the diffusion parameters obtained with QHAS, par ticularly the barrierto diffusion, and how they relate to the resultsofother Ipresent address: Infineon Technologies AG, Corporate Research, Otto-Hahn-Ring6, D-81739 Munich, Germany. 2Corresponding author: [email protected] M.e. TringidesandZ. Chvoj(eds.), CollectiveDiffusiononSurfaces:CorrelationEffectsandAdatomInteractions, 1-10. ©2001 KluwerAcademicPublishers.
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