Measurement of the Dissociation Rate of Molecular Ions PDF Download
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Author: Ch Ottinger
Publisher:
ISBN:
Category : Dissociation
Languages : en
Pages : 52
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Book Description
The time interval between the ionization of a molecule by electron impact and its dissociation was determined from the kinetic energy of the fragment ions. This technique allows a direct differential sampling of the dissociation rate at various times, in contrast to previous, integral methods. The use of disc-shaped molecular beam of 28 micrometers half-width and a draw-out field of 10,000 V/cm in the ionization region resulted in a minimum measured time interval of 7.4 nonoseconds. The longest times measured were between 5 and 6 microseconds. The time dependence of the decomposition rate was measured for two decompositions in butane, five in heptane, three in benzene, one in CD4 and one in CO2(++), with rather similar results. It was established that the decay is not exponential. All decay curves, plotted semi-logarithmically, were found to have an increasing slope towards shorter times, indicating contributions from a variety of rate constants in agreement with the predictions of the statistical theory of ion decompositions.
Author: Ch Ottinger
Publisher:
ISBN:
Category : Dissociation
Languages : en
Pages : 52
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Book Description
The time interval between the ionization of a molecule by electron impact and its dissociation was determined from the kinetic energy of the fragment ions. This technique allows a direct differential sampling of the dissociation rate at various times, in contrast to previous, integral methods. The use of disc-shaped molecular beam of 28 micrometers half-width and a draw-out field of 10,000 V/cm in the ionization region resulted in a minimum measured time interval of 7.4 nonoseconds. The longest times measured were between 5 and 6 microseconds. The time dependence of the decomposition rate was measured for two decompositions in butane, five in heptane, three in benzene, one in CD4 and one in CO2(++), with rather similar results. It was established that the decay is not exponential. All decay curves, plotted semi-logarithmically, were found to have an increasing slope towards shorter times, indicating contributions from a variety of rate constants in agreement with the predictions of the statistical theory of ion decompositions.
Author: Eugen Illenberger
Publisher: Springer Science & Business Media
ISBN: 3662073838
Category : Science
Languages : en
Pages : 357
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Book Description
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.
Author: William L Hase
Publisher: Elsevier
ISBN: 1483283623
Category : Science
Languages : en
Pages : 329
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Book Description
Advances in Classical Trajectory Methods, Volume 2: Dynamics of Ion-Molecule Complexes is a seven-chapter text that covers the considerable advances in the experimental and theoretical aspects of ion-molecular complexes, with particular emphasis on the dynamics and kinetics of their formation and ensuing unimolecular dissociation. This text also considers the development and testing of theoretical models for these formation and decomposition processes. The opening chapters discuss photoelectron photoion coincidence, ion cyclotron resonance, and crossed molecular beam studies of metastable ion-molecule complexes formed in ion-molecule collisions. These experimental studies involve comparisons with the predictions of statistical models, such as the Rice-Ramsperger-Kassel-Marcus and phase space theories, and comparisons with the reaction dynamics predicted by classical trajectory calculations. The succeeding chapter describes the double-well model for ion-molecular reactions taking place on a potential energy surface with a central barrier that separates two potential energy minima. These topics are followed by reviews of the quantum chemical calculation and reaction path Hamiltonian analysis of SN2 reactions, the transition state theory for ion-dipole and ion-quadrupole capture, and the capture and dynamical models for ion-molecule association to form a complex. The remaining chapters consider the temperature dependence of ion-molecule reactions, which proceed on a surface with many potential energy minima, specifically the ability to establish asymptotic limits for the reaction efficiency dependent upon the number of potential minima and the above relative probabilities. This book is of great value to experimental and theoretical chemists and physicists.
Author:
Publisher:
ISBN:
Category : Science
Languages : en
Pages : 992
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Book Description
Author: Colm T. Whelan
Publisher: Cambridge University Press
ISBN: 1107007445
Category : Science
Languages : en
Pages : 281
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Book Description
The first systematic treatment of fragmentation processes, ideal for graduate students and researchers in atomic collisions, laser physics and chemistry.
Author: Cheuk-Yiu Ng
Publisher: World Scientific
ISBN: 9789810204303
Category : Science
Languages : en
Pages : 590
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Book Description
This monograph reviews the recent progress in vacuum ultraviolet (VUV) photoionization and photodissociation processes. Photoionization, photoelectron, and fluorescence spectroscopic techniques have played an important role in revealing the photoionization and photodissociation dynamics of molecules in the vacuum ultraviolet region and in providing accurate energetic and spectroscopic information of ions as well as neutral molecules. The book represents the first detailed review of major experimental developments in the studies of single vacuum ultraviolet photon ionization and dissociation processes of gaseous molecules and clusters.
Author: John L. Holmes
Publisher: CRC Press
ISBN: 0203492471
Category : Science
Languages : en
Pages : 468
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Book Description
Assigning Structures to Ions in Mass Spectrometry describes the tools currently available for determining gas-phase ion structures. It surveys current experimental methods for ion production and separation as well as those designed to reveal qualitative and quantitative aspects of gas-phase ions. It also examines how and when to apply computational chemistry and theoretical calculations. Selected case studies illustrate specific challenges associated with ion structure assignment and thermochemical problems. Bringing together key results collected over the past four decades, the book contains the data for describing or identifying ions containing C alone and C with H, O, N, S, P, halogens, and small organic cations.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 570
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Book Description
Author:
Publisher:
ISBN:
Category : Energy development
Languages : en
Pages : 188
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Book Description
Author: Cheuk-Yiu Ng
Publisher: John Wiley & Sons
ISBN: 0470141921
Category : Technology & Engineering
Languages : en
Pages : 702
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Book Description
State-Selected and State-to-State Ion-Molecules Reaction Dynamics details the recent experimental and theoretical accomplishments in the field to date by some of its foremost researchers and theorists. Divided into two parts, each of which separately describe the experimental and theoretical aspects of the field, State-Selected and State-to-State Ion-Molecule Reaction Dynamics is an accessible, well organized look at a highly useful and emerging chemical specialty. Part 1, "Experiment," contains eight in-depth studies, which illustrate the key experimental work being done in the field today: Chapter 1 provide a comprehensive review of the theory and application of inhomogeneous rf fields for the study of the dynamics of low-energy ion-molecules processes Chapter 2 describes the application of multiphoton ionization (MPI) for the preparation of reactant ion states Chapter 3 reviews the application of MPI schemes for state specific cross-section measurements involving transition metal cations Chapter 4 describes the development of the threshold photoelectron secondary ion coincidence (TESICO) method Chapter 5 presents the conceptual and practical aspects of a multicoincidence technique Chapter 6 details the experimental results obtained using the photoionization and differential reactivity methods Chapter 7 reviews the several recent crossed beam studies of charge transfer and collision-induced dissociation systems involving atomic and molecular ions Chapter 8 is a survey of 15 years of high resolution crossed beam scattering of protons with atoms, diatoms, and poly-atomic molecules State-Selected and State-to-State Ion-Molecule Reaction Dynamics, Part 1: Experiment offers professionals a true state-of-the-science look at this fascinating and increasingly influential subject.
