Download or read book Ionisation d atomes de mol cules et de biomol cules par impact des ions multicharg s de hautes nergies written by Issam Abbas and published by . This book was released on 2008 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt: Les processus collisionnels ionisant de type ion-atome ou molécule sont fondamentaux dans plusieurs domaines de la physique et, plus récemment, en médecine nucléaire. Les théories disponibles, quantiques ou semi-classiques, ne peuvent pas traiter de grosses cibles moléculaires comme les biomolécules. Pour résoudre ce problème nous avons développé une méthode purement classique. Dans ce travail, nous présentons notre modèle classique qui est basé sur deux autres approximations classiques : Classical Over-Barrier (COB) et Classical Trajectory Monte Carlo (CTMC). Ce modèle est particulièrement conçu à l'étude des collisions entre des ions multichargés et des atomes ou molécules. Ce modèle nous permet de calculer les sections efficaces, de capture ou d'ionisation, simples ou multiples. Nous l'avons appliqué, en premier lieu, sur des cibles atomiques ou moléculaires simples (H, He, H2 et H2O) dont des données expérimentales ou théoriques nombreuses sont disponibles. Ces calculs nous ont permit de vérifier la validité de notre modèle pour des cibles comme les biomolécules. Nous avons appliqué le modèle sur deux des biomolécules constituant de l'ADN (Adénine et Cytosine) ce qui est impossible à réaliser avec les approximations actuellement disponibles.

Download or read book Methods and Mechanisms for Producing Ions from Large Molecules written by K.G. Standing and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 319 pages. Available in PDF, EPUB and Kindle. Book excerpt: A NATO Advanced Research Workshop on Methods and Mechanisms for Producing Ions from Large Molecules was held at Minaki Lodge, Minaki, Ontario, Canada, from 24 to 28 June 1990. The workshop was hosted by the time-of-flight group of the Department of Physics at the University of Manitoba, and was attended by 64 invited participants from around the world. Twenty-nine invited talks were given and 19 papers were presented as posters. Of the 48 contributions, 38 are included in these proceedings. The conference was organized to study the rapidly changing field of mass spectrometry of biomolecules. Particle-induced desorption (especially with MeV particles) has been the most effective method of producing molecular ions from biomolecules. An important part of the workshop was devoted to recent developments in this field, particularly to progress in understanding the fundamentals of the desorption process. In this respect, the meeting was similar to previous conferences in Marburg, FRG (1978); Paris, F (1980); Uppsala, S (1981); College Station, USA (1983,1984); Wangerooge, FRG (1986); Orsay, F (1988); Spiekeroog, FRG (1989); and to the IFOS series of meetings at Munster, FRG (1981,1983,1985,1987) and L6vAnger, S (1989). As in the most recent of these meetings, there was some emphasis on new developments, particularly cluster bombardment. A departure from the concentration on particle bombardment processes at this conference was inspired by the dramatic results obtained with two new methods for producing molecular ions from large molecules: matrix-assisted laser desorption and electrospray.

Download or read book Molecular Ions written by Joseph Berkowitz and published by Springer. This book was released on 1983-05-31 with total page 618 pages. Available in PDF, EPUB and Kindle. Book excerpt: The present volume contains contributions presented at the NATO Advanced Study Institute on Molecular Ions held on the island of Kos, Greece, from September 30 to October 10, 1980. The meeting was attended by some 60 participants from 15 different countries. It was the first meeting devoted exclusively to the topic of molecular ions. Its vitality derived from bringing together experts and students from a wide variety of disciplines, whose studies bear upon the structure of molecular ions. The aim of the meeting was to assemble these scientists, representing many countries in Europe and North America, to discuss the advances and capabilities of the various experimental and theoretical approaches and to point out un solved problems and directions for future research. The format, in volving lecturers and students, served as a tutorial. Molecular ions play an important role in very diverse fields of nature such as reactions in the ionosphere, the processes of forma tion of molecules in dense interstellar clouds, and the magnetohydro dynamics of plasmas used for energy generation. Our understanding of the properties of molecular ions, their electronic and geometric structures, has been developing from a variety of sources, as far removed as tickling ions with radiofre quency radiation and smashing them apart at relativistic energies. Various laser techniques are described, and the queen of structural determination, spectroscopy, is well represented. On the instrumen tal side, older techniques have been perfected and new methods have evolved.