Studies Of The Dissociation And Energetics Of Gaseous Ions
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Studies Of The Dissociation And Energetics Of Gaseous Ions
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Author : Simon-John King
language : en
Publisher:
Release Date : 2009
Studies Of The Dissociation And Energetics Of Gaseous Ions written by Simon-John King and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009 with categories.
Studies Of The Dissociation And Energetics Of Gaseous Ions
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Author : Simon J. King
language : en
Publisher:
Release Date : 2009
Studies Of The Dissociation And Energetics Of Gaseous Ions written by Simon J. King and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009 with categories.
In this thesis the electron ionization of a number of small gas phase molecules is investigated using pulsed time-of-flight mass spectrometry coupled with a 2-D ion coincidence technique. The simultaneous acquisition of conventional TOF mass spectra and ion coincidence mass spectra, enables fragment ions formed by dissociative single, double, and triple ionization, to be distinguished and quantified. Relative partial ionization cross sections (PICS) and precursor specific relative PICS are derived for the formation of positively charged fragment ions, following electron ionization of C_2F_6, SiCl_4, C_2H_2, CO_2 and H_2O, in the ionizing electron energy range 30-200 eV. Such information is of considerable importance for the accurate modelling and understanding of the chemical processes occurring in highly energised media, such as industrial plasmas and planetary atmospheres. The relative PICS quantify the overall yield for each fragment ion, while the precursor specific relative PICS quantify the contributions to the fragment ion yield from single, double and triple ionization, respectively. Relative PICS for the formation of ion pairs via dicationic dissociation are also presented. Comparisons of the relative PICS data to existing measurements of the PICS for these molecules reveals, in many cases, considerable discrepancies for the formation of the low-mass ionic fragments, for which the present cross section measurements are considerably larger. In general, these differences are rationalised by the inefficient collection of energetic ions in the previous determinations of the PICS, in particular for those ionic fragments formed via dissociative multiple ionization, which are efficiently collected in the present investigations. The precursor specific relative PICS data provides a more detailed chemical description of each individual partial ionization cross section, and can be interpreted to explain the various energy-dependent features of the PICS curves observed in previous studies. For example, for the fragment ions formed by electron ionization of SiCl_4, the low energy maxima of the PICS curves are due to contributions from single ionization involving mainly indirect ionization processes, while the higher energy maxima are due to dissociative double ionization. For the electron ionization of small gas phase molecules, the general trend appears to be that the major contributions to the yield of small fragment ions comprising only a few atoms, are from dissociative double ionization, above 100 eV. The shapes of the peaks recorded in the 2-D ion coincidence spectra are interpreted to provide additional information on the fragmentation dynamics and energetics of the charge-separating dissociations of C_{2}F_{6}\: {2+}, SiCl_{4}\: {2+}, C_{2}H_{2}\: {2+}, CO_{2}\: {2+} and H_2O {2+}. Estimates of the dication precursor state energies for forming ion pairs are derived, and are shown to be in good agreement with existing experimental and theoretical data. The measurements presented in this thesis include the first estimates of the electronic state energies of the C_{2}F_{6}\: {2+} and SiCl_{4}\: {2+} dications. A breakdown scheme for C_{2}H_{2}\: {2+} is derived, which in combination with the relative PICS for ion pair formation, yields branching ratios for primary two-body charge separating dissociation. Comparison of this scheme with recent theoretical calculations suggests that below 75 eV, C_{2}H_{2}\: {2+} dissociates predominantly on the ground triplet potential energy surface ({ 3}\sum\,_{g}\, -). By contrast, the dissociations of the C_{2}F_{6}\: {2+} dication are postulated to be predominantly impulsive in nature, for which fastsequential decay mechanisms are proposed for forming ion pairs.
Energetics Of Gaseous Ions
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Author : Henry M. Rosenstock
language : en
Publisher: American Institute of Physics
Release Date : 1977
Energetics Of Gaseous Ions written by Henry M. Rosenstock and has been published by American Institute of Physics this book supported file pdf, txt, epub, kindle and other format this book has been release on 1977 with Science categories.
The Formation Dissociation And Reactivity Of Gaseous Ions
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Author : K. M. Douglas
language : en
Publisher:
Release Date : 2012
The Formation Dissociation And Reactivity Of Gaseous Ions written by K. M. Douglas and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012 with categories.
This thesis presents the results of a series of experiential investigations into the formation, dissociation and reactivity of gaseous ions. Firstly, using a time-of-flight mass spectrometer coupled with a 2D ion coincidence technique, studies of the electron ionization of a number of small gas-phase molecules are presented. Relative partial ionization cross-sections (PICS) are derived for the formation of positively charged fragment ions, following electron ionization of H2S, CH3OH and CF3I. The 2D ion coincidence technique enables fragment ions formed by dissociative single, double, triple and quadruple ionization to be distinguished and quantified. This information also allows precursor specific relative PICS to be determined. While the relative PICS quantify the overall yield of each fragment ion, the precursor specific relative PICS quantify the contribution from single, double, triple and quadruple ionization to the relative yields of each fragment ion. Such information is essential for the accurate modelling, and the understanding, of the chemical processes occurring in energetic environments, such as industrial plasmas and planetary atmospheres. Comparison of the relative PICS data to existing measurements of the PICS for these molecules generally shows good agreement for experiments in which the efficient collection of translationally energetic ions is demonstrated. In addition, information on the energetics and dissociation dynamics involved in the fragmentation of H2S2+, CH3OH2+, CF3I2+ and CF3I3+ are provided by interpretation of ion pair peaks recorded in the 2D ion coincidence spectra. Secondly, this thesis also presents the results of an investigation into the photoionization of CF3I, using the threshold photoelectron-photoion-photoion coincidence (iPEPICO) endstation on the vacuum-ultraviolet beamline at the Swiss Light Source. These experiments were part of a scoping study to see if this existing apparatus could be used to study multiple ionization. The photoionization spectra are interpreted and discussed, and issues with the current experimental arrangement, which may be improved for future visits, are addressed. Finally, studies of I2+ collisions with OCS, carried out using a crossed ion beam experiment with a time-of-flight mass spectrometer, are presented. Two bond-forming reactions producing IO+ and IS+ are observed, together with the more ubiquitous electron transfer reactions. These electron transfer reactions are rationalised using the Reaction Window model.
Gaseous Molecular Ions
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Author : Eugen Illenberger
language : en
Publisher: Springer Science & Business Media
Release Date : 2013-03-09
Gaseous Molecular Ions written by Eugen Illenberger and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013-03-09 with Science categories.
Most of the matter in our solar system, and, probably, within the whole universe, exists in the form of ionized particles. On the other hand, in our natural environ ment, gaseous matter generally consists of neutral atoms and molecules. Only under certain conditions, such as within the path oflightning or in several technical devices (e. g. gas discharges, rocket engines, etc. ) will some of the atoms and molecules be ionized. It is also believed that the chemistry of the earth's troposphere predomi nantly proceeds via reactions between neutral particles. (The complex system of atmospheric chemistry will be treated in one of the forthcoming volumes to this series. ) Why, then, are ions considered so important that hundreds oflaboratories all over the world (including some of the most prestigious) are involved in research pro grams on ions, covering many different facets, from biochemistry to physics? One may obtain as many different answers as there are research groups busy in this field. There is, however, one simple, common feature which makes it attractive to work with ions: since they carry one or more net elementary charges, they can easily be gui ded, focused or separated by appropriate electric and magnetic fields, and, last but not least, they can easily be detected. Apart from these advantages, which are welcome and appreciated by the researcher, the study of molecular ions can provide insight into very fundamental aspects of the general behavior of molecules.
Gas Phase Ion Chemistry
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Author : Michael T. Bowers
language : en
Publisher: Academic Press
Release Date : 2013-10-22
Gas Phase Ion Chemistry written by Michael T. Bowers and has been published by Academic Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013-10-22 with Science categories.
Gas Phase Ion Chemistry, Volume 2 covers the advances in gas phase ion chemistry. The book discusses the stabilities of positive ions from equilibrium gas-phase basicity measurements; the experimental methods used to determine molecular electron affinities, specifically photoelectron spectroscopy, photodetachment spectroscopy, charge transfer, and collisional ionization; and the gas-phase acidity scale. The text also describes the basis of the technique of chemical ionization mass spectrometry; the energetics and mechanisms of unimolecular reactions of positive ions; and the photodissociation of gas-phase ions. The applications of molecular beam techniques to the study of ion-molecule collisions; as well as the variational treatment of charge transfer reactions are also encompassed. Chemists and biochemists will find the book invaluable.
Fundamentals Of Gas Phase Ion Chemistry
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Author : K.R. Jennings
language : en
Publisher: Springer Science & Business Media
Release Date : 2012-12-06
Fundamentals Of Gas Phase Ion Chemistry written by K.R. Jennings and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012-12-06 with Science categories.
This volume presents the proceedings of the 1990 Advanced Study Institute entitled "Fundamentals of Gas Phase Ion Chemistry" held at Mont Ste. Odile , Alsace, France, 25th June -6th July, 1990. The Institute brought together over 100 physicists, physical and organic chemists working on a wide variety of topics with gas-phase ion chemistry as the common theme. Many different viewpoints, making use of very different experimental and theoretical approaches, were brought to bear on the subject and provided a stimulating and up-to-date account of the subject. Although the Institute was built around the invited lectures, many specific points were addressed in workshops which consisted of informal discussion groups which were organised by participants during the Institute. This volume therefore contains not only chapters based on the lectures but summaries of many of the workshops which adds considerably to the diversity of information presented. This Advanced Study Institute was the fifth in a series of NATO-sponsored institutes devoted to various aspects of the physics and chemistry of gas phase ions. These meetings have been held every four years since the first, held in Biarritz in 1974, considered "Interactions between Ions and Molecules". The five volumes which comprise the proceedings of these meetings illustrate very clearly the many advances in theory and experiment which have taken place over the last 20 years.
Dissociative Recombination Of Molecular Ions With Electrons
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Author : Steven L. Guberman
language : en
Publisher: Springer Science & Business Media
Release Date : 2012-12-06
Dissociative Recombination Of Molecular Ions With Electrons written by Steven L. Guberman and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012-12-06 with Science categories.
Dissociative Recombination of Molecular Ions with Electrons is a comprehensive collection of refereed papers describing the latest developments in dissociative recombination research. The papers are written by the leading researchers in the field. The topics covered include the use of microwave afterglows, merged beams and storage rings to measure rate coefficients and to identify the products and their yields. The molecules studied range in size from the smallest, H2+, to bovine insulin ions. The theoretical papers cover the important role of Rydberg states and the use of wave packets and quantum defect theory to deduce cross sections, rate constants and quantum yields. Several theoretical and experimental papers address the controversial topic of H3+ dissociative recombination and its importance in the interstellar medium. Dissociative recombination studies of other molecular ions in the interstellar medium and in cometary and planetary atmospheres are covered. Ionization is an important competitive process to dissociative recombination and its competition with predissociation and its role in the reverse process of the association of neutral species is presented. Dissociative attachment, in which an electron attaches to a neutral molecule, has many similarities to dissociative recombination. The topics covered include the accurate calculation of electron affinities, attachment to molecules, clusters, and to species absorbed on solid surfaces and electron scattering by a molecular anion.
Studies Of H 2 Dissociation
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Author : A. W. Ehler
language : en
Publisher:
Release Date : 1964
Studies Of H 2 Dissociation written by A. W. Ehler and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1964 with Dissociation categories.
Advances In Gas Phase Ion Chemistry
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Author :
language : en
Publisher: Elsevier
Release Date : 1996-05-14
Advances In Gas Phase Ion Chemistry written by and has been published by Elsevier this book supported file pdf, txt, epub, kindle and other format this book has been release on 1996-05-14 with Science categories.
Advances in Gas Phase Ion Chemistry