ISSN:0005-9021    

DOI:10.1002/bbpc.19730770802

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1973

数据来源: WILEY

ISSN:0005-9021    

DOI:10.1002/bbpc.19730770803

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1973

数据来源: WILEY

摘要:

AbstractAn appraisal of the classical trajectory method as a tool for studying ion‐molecule reactions is presented. The method has recently been extended to incorporate nonadiabatic processes such as charge transfer. This approach has been applied to two fundamental ion‐molecule reactions, Ar++ H2and H++ H (and isotopic variants). Important conclusions concerning the dynamics of these reactions are discussed. Detailed comparisons with the results of molecular beam experiments are included. The agreement between the computer simulations and experiment is indicative of a very promising future for the trajectory method. Provided that reliable potential energy surfaces can be constructed, the method should be capable of accurate prediction of most reaction attributes, e.g. reaction rates, product internal energy distributions, etc. In addition, it can provide unambiguous information about reaction mechanisms that cannot be obtained by experimental means, and it can be used to assess the validity of models which employ simplified forces or dynamics. Possible directions are suggested for future work in this a

ISSN:0005-9021    

DOI:10.1002/bbpc.19730770804

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1973

数据来源: WILEY

摘要:

AbstractStudies of reactive scattering of ions have provided information on collision kinematics of chemical reactions of ions: on microscopic reaction mechanisms, on partitioning of energy in a chemical reaction, and on cross sections of these processes. Reactions can be investigated over a wide range of collision energies and thus the influence of translational energy on the course of a chemical reaction can be studied. Data on ion‐molecule processes are of importance for kinematics of chemical reactions in general. Recent development in theory requires more detailed kinematic information to be obtained from experiments, namely data on CM‐angular distributions, on relative translational energies of products, on internal states of products, and on cross sections and their dependence on collision energy. Valuable kinematic information can be obtained from nonreactive scattering studies and from electronic correlation studies. Experimental techniques and data handling procedures are reviewed. Examples of both direct processes and intermediate complex formation are discus

ISSN:0005-9021    

DOI:10.1002/bbpc.19730770805

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1973

数据来源: WILEY

摘要:

AbstractBased on asymptotic solutions of the Boltzmann equation a theory for the rate of endothermic ion‐molecule reactions in intermediate and high E/N‐fields is outlined. An effective temperature scale may be defined by Application to several reactions in nitrogen and oxygen reveals the validity of the analysis for the determination of total collision cross sections, activation energies and frequency factors of reacti

ISSN:0005-9021    

DOI:10.1002/bbpc.19730770806

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1973

数据来源: WILEY

摘要:

AbstractThe value of elastic scattering experiments for the determination of interaction potentials between ions and neutral particles is discussed. After a description of typical experimental setups a short introduction to the theory of rainbow scattering is given. Several methods for the evaluation of experimental results are presented. The measured differential cross‐sections and the resulting potential curves are discussed for the proton‐rare gas systems which have been extensively studied. In some cases the experimental data can be compared with quantum chemical calculations. The system He+‐ He is chosen to outline the symmetry effects observed in the differential elastic scattering cross‐section in the case of the symmetric rare gas ion‐rare gas atom systems. The potential depths obtained from the experimental rainbow structures are compared with the results of quantum chemical calculations and of semiempirical estimates. Some data derived from elastic scattering of He+by rare‐gas atoms are presented. Finally experimental results are reviewed for the elastic scattering of protons by simple molecules and of H+2by Ar‐

ISSN:0005-9021    

DOI:10.1002/bbpc.19730770807

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1973

数据来源: WILEY

摘要:

AbstractInelastic scattering processe in collisions of positive ions with neutral gas atoms and molecules can be divided into three main groups: (1) Inelastic scattering involving electronic transitions with subdivisions into final vibrational and rotational states of the collision products; (2) inelastic scattering involving vibration‐rotation transitions without a change in electronic state with subdivisions into final rotational states; and (3) inelastic scattering via pure rotational transitions. Recent advances in experimental techniques have given a great deal of new information about almost all these processes. For (1), both inelastic scattering experiments and optical fluorescence techniques have shown that although the total cross sections for electronic transitions are remarkably uniform for a large number of systems there are wide individual variations in the details of final vibrational and rotational states produced in the charge transfer and non‐charge transfer channels. For (2), it has been found that vibration‐rotation transitions are the most intense components of the inelastic scattering spectrum with cross sections of the order of 1 A2at maximum for some systems. Because of experimental difficulties, little is known about (3) at the present time. In addition to inelastic processes, superelastic processes have now been studied in detail in the laboratory, both for electronic and vibration‐rotation transitions. These processes promise to provide a very interesting opportunity for investigations in the future into, for example, the metastable populations of ion beams, Unfortunately, we lack the ability at the present time to make theoretical predictions for the behavior of any but the simplest of these pr

ISSN:0005-9021    

DOI:10.1002/bbpc.19730770808

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1973

数据来源: WILEY

摘要:

AbstractThis review discusses recent results on collision processes of accelerated atoms which lead to ion production. Five general classes of reactions are described ‐ collision‐induced dissociative ion pair formation (polar dissociation), electron transfer, associative ionization, reactive (rearrangement) ionization, and simple collisional ionization. The review is restricted to ion product reactions that have been studied in molecular beam experiments in which two neutral species collide with relative energies up to 20 eV, and the endoergicity of the reaction is provided by the kinetic energy of one of the partners. The accelerating techniques capable of producing beams of fast atoms and molecules in this important energy region are described.Characteristics of such reactions are the cross sections for the various reaction channels and their dependences on the relative energy (i.e., the excitation functions), the behavior of the cross section near threshold, the relative importance of translational and internal energy in promoting the reaction, and the dynamics of the collisions as revealed by the angular distributions of the products. Illustrative results on these properties are presented. The polar dissociation of the thallium halides by accelerated Xe and Kr atoms, and the dynamics of a number of reactions of fast metal and non‐metal atoms with several molecules are described in d

ISSN:0005-9021    

DOI:10.1002/bbpc.19730770809

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1973

数据来源: WILEY

摘要:

AbstractThe present state of knowledge of the mechanism of associative ionization reactions in gases will be reviewed. Recent experiments employing molecular beam techniques for the study of these processes will be discussed; in particular, the associative and rearrangement ionization collisions of rare gas metastable atoms in the rare gases, hydrogen, and water vapor. Measurements of cross sections for secondary collision processes of the ions formed by Penning and associative ionization will also be presented.

ISSN:0005-9021    

DOI:10.1002/bbpc.19730770810

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1973

数据来源: WILEY

摘要:

AbstractA review is presented of recent experimental investigations dealing with the ionization of various atoms and molecules in collisions with metastable rare gas atoms. These investigations include absolute cross section measurements, mass spectrometric analysis of the ions formed, and electron spectroscopic analysis of the electrons ejected. The results are discussed in terms of a potential curve model for Penning ionization, which essentially is equivalent to a description in Born‐Oppenheimer approximation of the process, with the motion of the colliding heavy particles treated classically. The approximate validity of this description is shown to be supported by the experimental results. The discussion of the experimental data in this frame yields detailed in formation on the physical quantities governing the Penning ionization process. In the case of the ionization of molecules it is shown that the Penning process is vertical and in simple cases leads to a population of vibrational states of the ion in accord with the Franck‐Condon transition probabilities. Observed deviations from this behaviour, and other complications, due to competing processes, arising in the case of molecules are discus

ISSN:0005-9021    

DOI:10.1002/bbpc.19730770811

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1973

数据来源: WILEY