Download or read book PHOTODESORPTION D IONS DANS DES ATOMES ET DES MOLECULES CONDENSES OU ADSORBES written by Laurent Philippe and published by . This book was released on 1994 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt: NOUS PRESENTONS UN TRAVAIL EXPERIMENTAL SUR LA PHOTODESORPTION D'IONS DANS LES ATOMES ET LES MOLECULES CONDENSES OU ADSORBES. NOUS UTILISONS COMME SOURCE DE PHOTONS LE RAYONNEMENT SYNCHROTRON DANS LA GAMME D'ENERGIE 10-150 EV. CE MEMOIRE PRESENTE LA PREMIERE ETUDE DE PHOTODESORPTION D'IONS OU L'ON A PU SIMULTANEMENT SELECTIONNER EN MASSE ET EN ENERGIE CINETIQUE LES IONS DESORBES. NOUS MONTRONS QUE LA DESORPTION D'IONS EST PRINCIPALEMENT INDUITE PAR LA FORMATION D'ETATS ELECTRONIQUES MULTIPLEMENT EXCITES (PAIRES D'EXCITONS, ETATS SATELLITES, DOUBLE ET TRIPLE IONISATION, IONISATION SIMULTANEE DE PLUSIEURS ATOMES). NOS MESURES D'ENERGIES CINETIQUES DES IONS DESORBES MONTRENT QU'EN GENERAL LES ENERGIES CINETIQUES SONT BEAUCOUP FAIBLES QUE CE QUI ETAIT ATTENDU. CECI EST DU AU ROLE DES PROCESSUS DE RELAXATION (EX: FLUORESCENCE) DES ETATS ELECTRONIQUES EXCITES. CEPENDANT DANS LA PLUPART DES CAS LA RELAXATION N'EST PAS COMPLETE ET LA SELECTIVITE DE L'EXCITATION EST PRESERVEE DANS LA DESORPTION (ARGON ET CO CONDENSE EN MULTICOUCHES ET OXYGENE CHIMISORBE SUR LE SILICIUM). POUR LES MOLECULES CONDENSEES EN MULTICOUCHES, NOUS AVONS ETUDIE LES PROCESSUS DE FRAGMENTATION. CES PROCESSUS SE SONT AVERES TRES DIFFERENTS DE LA PHASE GAZEUSE PUISQU'A UNE MEME ENERGIE DE PHOTON SEULS LES ETATS SATELLITES DONNENT DE LA DESORPTION D'IONS FRAGMENTS (CO, CH#4 ET H#2O) ET QUE LES ENERGIES CINETIQUES MESUREES EN DESORPTION D'IONS FRAGMENTS SONT PLUS FAIBLES QUE LES ENERGIES MESUREES EN PHOTOFRAGMENTATION D'IONS. TOUJOURS DANS LES MOLECULES CONDENSEES, NOUS AVONS EXPLIQUE LA FORMATION DES PRODUITS DESORBES COMPLEXES OBSERVES PAR DES REACTIONS ION-MOLECULE EN SURFACE OU PAR LA PHOTOFRAGMENTATION D'AGREGATS EN SURFACE. ENFIN DANS LES ADSORBATS SUR SILICIUM, NOS ETUDES MONTRENT QUE LA PHOTODESORPTION D'IONS PEUT ETRE REALISEE SUR DES SITES PARFAITEMENT BIEN DEFINIS DU POINT DE VUE GEOMETRIQUE ET ELECTRONIQUE

Download or read book Condensation et adsorption des mol cules sur une surface en atmosph re rar fi e written by Fernand-Marcel Devienne and published by FeniXX. This book was released on 1952-01-01T00:00:00+01:00 with total page 96 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cet ouvrage est une réédition numérique d’un livre paru au XXe siècle, désormais indisponible dans son format d’origine.

Download or read book DYNAMIQUE DE DESORPTION D IONS STIMULEE PAR IMPACT D ELECTRONS DE BASSE ENERGIE 0 25 EV SUR LES MOLECULES O 2 N 2O ET CF 4 CONDENSEES SUR DES SUBSTRATS METALLIQUES written by MOHAMED NEJIB.. HEDHILI and published by . This book was released on 1998 with total page 170 pages. Available in PDF, EPUB and Kindle. Book excerpt: L'INTERACTION D'ELECTRONS DE BASSE ENERGIE (0 - 25 EV) AVEC DES MOLECULES CONDENSEES CONDUIT A LA DESORPTION D'IONS NEGATIFS ET POSITIFS DONT LES SPECTRES DE RENDEMENT ET LES DISTRIBUTIONS D'ENERGIE CINETIQUE PERMETTENT DE DECRIRE LES MECANISMES ET LA DYNAMIQUE DES PROCESSUS EN JEU. DES ETUDES SUR LES MOLECULES O 2, N 2O ET CF 4 CONDENSEES SUR UN METAL (PT) MONTRENT QUE LES MECANISMES (L'ATTACHEMENT DISSOCIATIF ET LA DISSOCIATION DIPOLAIRE) ET LA DYNAMIQUE DE DESORPTION DEPENDENT DES CONDITIONS DE CONDENSATION. - EN MULTICOUCHES DE MOLECULES D'OXYGENE O 2, LA FORMATION DE RESONANCES O - * 2 DE SYMETRIE +, INTERDITES EN PHASE GAZEUSE, CONTRIBUE A LA DESORPTION D'IONS O - ET QUE LA PREDISSOCIATION D'ETATS DE RYDBERG O * 2 EST RESPONSABLE DE LA DESORPTION D'IONS O - ET O + VIA LE PROCESSUS DE DISSOCIATION DIPOLAIRE. - EN MONOCOUCHE OU SUBMONOCOUCHE DE O 2, UN PROCESSUS DE DESORPTION D'IONS O - TRES ENERGETIQUES IMPLIQUANT UN TRANSFERT DE CHARGE DU SUBSTRAT METALLIQUE VERS DES FRAGMENTS NEUTRES O FORMES PAR EXCITATION DISSOCIATIVE PAR IMPACTS D'ELECTRONS SUR O 2 CONDENSE EST MIS EN EVIDENCE. - DES DISTRIBUTIONS D'ENERGIE CINETIQUE D'IONS O - MONTRENT QUE LA DYNAMIQUE DE DESORPTION DEPEND DE L'ENVIRONNEMENT DANS LEQUEL LES MOLECULES O 2 SONT CONDENSEES ET QU'EN PLUS DES COLLISIONS MULTIPLES DES ELECTRONS INCIDENTS ET DES IONS, LES PHENOMENES DE FLUCTUATION DE L'ENERGIE DE POLARISATION ET DE CREATION DE PHONONS DANS LE SUBSTRAT ET LE MILIEU CONDENSE JOUENT UN ROLE IMPORTANT. - ENFIN L'INTERACTION D'ELECTRONS AVEC L'OXYGENE MOLECULAIRE CONDENSE CONDUIT A LA PRODUCTION D'OZONE O 3 EN SURFACE ET EN VOLUME DE L'ADOSORBAT VIA DES REACTIONS ATOMES-MOLECULES, AVEC UN SEUIL A 3.5 EV D'ENERGIE INCIDENTE.

Download or read book Chemisorption and Reactivity on Supported Clusters and Thin Films written by R.M. Lambert and published by Springer Science & Business Media. This book was released on 2013-04-17 with total page 534 pages. Available in PDF, EPUB and Kindle. Book excerpt: Heterogeneous catalysis provides the backbone of the world's chemical and oil industries. The innate complexity of practical catalytic systems suggests that useful progress should be achievable by investigating key aspects of catalysis by experimental studies on idealised model systems. Thin films and supported clusters are two promising types of model system that can be used for this purpose, since they mimic important aspects of the properties of practical dispersed catalysts. Similarly, appropriate theoretical studies of chemisorption and surface reaction clusters or extended slab systems can provide valuable information on the factors that underlie bonding and catalytic activity. This volume describes such experimental and theoretical approaches to the surface chemistry and catalytic behaviour of metals, metal oxides and metal/metal oxide systems. An introduction to the principles and main themes of heterogeneous catalysis is followed by detailed accounts of the application of modern experimental and theoretical techniques to fundamental problems. The application of advanced experimental methods is complemented by a full description of theoretical procedures, including Hartree-Fock, density functional and similar techniques. The relative merits of the various approaches are considered and directions for future progress are indicated.

Download or read book Application of Particle and Laser Beams in Materials Technology written by P. Misaelides and published by Springer Science & Business Media. This book was released on 1995-01-31 with total page 702 pages. Available in PDF, EPUB and Kindle. Book excerpt: The development of advanced materials with preselected properties is one of the main goals of materials research. Of especial interest are electronics, high-temperature and superhard materials for various applications, as well as alloys with improved wear, corrosion and mechanical resistance properties. The technical challenge connected with the production of these materials is not only associated with the development of new specialised preparation techniques but also with quality control. The energetic charged particle, electron and photon beams offer the possibility of modifying the properties of the near-surface regions of materials without seriously affecting their bulk, and provide unique analytical tools for testing their quality. Application of Particle and Laser Beams in Materials Technology provides an overview of this rapidly expanding field. Fundamental aspects concerning the interactions and collisions on atomic, nuclear and solid state scale are presented in a didactic way, along with the application of a variety of techniques for the solution of problems ranging from the development of electronics materials to corrosion research and from archaeometry to environmental protection. The book is divided into six thematic units: Fundamentals, Surface Analysis Techniques, Laser Beams in Materials Technology, Accelerator-Based Techniques in Materials Technology, Materials Modification and Synchrotron Radiation.

Download or read book Astrochemistry and Astrobiology written by Ian W. M. Smith and published by Springer Science & Business Media. This book was released on 2012-10-28 with total page 353 pages. Available in PDF, EPUB and Kindle. Book excerpt: Astrochemistry and Astrobiology is the debut volume in the new series Physical Chemistry in Action. Aimed at both the novice and experienced researcher, this volume outlines the physico-chemical principles which underpin our attempts to understand astrochemistry and predict astrobiology. An introductory chapter includes fundamental aspects of physical chemistry required for understanding the field. Eight further chapters address specific topics, encompassing basic theory and models, up-to-date research and an outlook on future work. The last chapter examines each of the topics again but addressed from a different angle. Written and edited by international experts, this text is accessible for those entering the field of astrochemistry and astrobiology, while it still remains interesting for more experienced researchers.

Download or read book Physics Briefs written by and published by . This book was released on 1987 with total page 858 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book High Resolution Laser Spectroscopy written by K. Shimoda and published by Springer. This book was released on 2014-03-12 with total page 380 pages. Available in PDF, EPUB and Kindle. Book excerpt: With contributions by numerous experts

Download or read book Molecular Ions written by Terry Alan Miller and published by North-Holland. This book was released on 1983 with total page 300 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Protostars Planets written by Tom Gehrels and published by . This book was released on 1978 with total page 776 pages. Available in PDF, EPUB and Kindle. Book excerpt: Unique source book on star formation and the origin of planetary systems from some 35 distinguished authors. Topics include the formation of stars from the cloudy to the stellar to the planetary state. Special emphasis on stars believed capable of producing planets.