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Collisional

While monomolecular collision-free predissociation excludes the preparation process from explicit consideration, themial imimolecular reactions involve collisional excitation as part of the unimolecular mechanism. The simple mechanism for a themial chemical reaction may be fomially decomposed into tliree (possibly reversible) steps (with rovibronically excited (CH NC) ) ... [Pg.765]

For themial unimolecular reactions with bimolecular collisional activation steps and for bimolecular reactions, more specifically one takes the limit of tire time evolution operator for - co and t —> + co to describe isolated binary collision events. The corresponding matrix representation of f)is called the scattering matrix or S-matrix with matrix elements... [Pg.773]

Crosley D R 1981 Collisional effects on laser-induced fluorescence Opt. Eng. 20 511-21... [Pg.821]

Duncan M A, Bierbaum V M, Ellison G B and Leone S R 1983 Laser-induced fluorescence studies of ion collisional excitation in a drift field rotational excitation of N in He J. Chem. Phys. 79 5448-56... [Pg.822]

Figure A3.12.2. Relation of state oeeupation (sehematieally shown at eonstant energy) to lifetime distribution for the RRKM theory and for various aetiial situations. Dashed eiirves in lifetime distributions for (d) and (e) indieate RRKM behaviour, (a) RRKM model, (b) Physieal eounterpart of RRKM model, (e) Collisional state seleetion. (d) Chemieal aetivation. (e) Intrinsieally non-RRKM. (Adapted from [9].)... Figure A3.12.2. Relation of state oeeupation (sehematieally shown at eonstant energy) to lifetime distribution for the RRKM theory and for various aetiial situations. Dashed eiirves in lifetime distributions for (d) and (e) indieate RRKM behaviour, (a) RRKM model, (b) Physieal eounterpart of RRKM model, (e) Collisional state seleetion. (d) Chemieal aetivation. (e) Intrinsieally non-RRKM. (Adapted from [9].)...
To detect tlie initial apparent non-RRKM decay, one has to monitor the reaction at short times. This can be perfomied by studying the unimolecular decomposition at high pressures, where collisional stabilization competes with the rate of IVR. The first successful detection of apparent non-RRKM behaviour was accomplished by Rabinovitch and co-workers [115], who used chemical activation to prepare vibrationally excited hexafluorobicyclopropyl-d2 ... [Pg.1035]

In this chapter we shall first outline the basic concepts of the various mechanisms for energy redistribution, followed by a very brief overview of collisional intennoleciilar energy transfer in chemical reaction systems. The main part of this chapter deals with true intramolecular energy transfer in polyatomic molecules, which is a topic of particular current importance. Stress is placed on basic ideas and concepts. It is not the aim of this chapter to review in detail the vast literature on this topic we refer to some of the key reviews and books [U, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, and 32] and the literature cited therein. These cover a variety of aspects of tire topic and fiirther, more detailed references will be given tliroiighoiit this review. We should mention here the energy transfer processes, which are of fiindamental importance but are beyond the scope of this review, such as electronic energy transfer by mechanisms of the Forster type [33, 34] and related processes. [Pg.1046]

Figure A3.13.1. Schematic energy level diagram and relationship between mtemiolecular (collisional or radiative) and intramolecular energy transfer between states of isolated molecules. The fat horizontal bars indicate diin energy shells of nearly degenerate states. Figure A3.13.1. Schematic energy level diagram and relationship between mtemiolecular (collisional or radiative) and intramolecular energy transfer between states of isolated molecules. The fat horizontal bars indicate diin energy shells of nearly degenerate states.
A3.13.3.1 THE MASTER EQUATION FOR COLLISIONAL RELAXATION REACTION PROCESSES... [Pg.1050]

The fimdamental kinetic master equations for collisional energy redistribution follow the rules of the kinetic equations for all elementary reactions. Indeed an energy transfer process by inelastic collision, equation (A3.13.5). can be considered as a somewhat special reaction . The kinetic differential equations for these processes have been discussed in the general context of chapter A3.4 on gas kmetics. We discuss here some special aspects related to collisional energy transfer in reactive systems. The general master equation for relaxation and reaction is of the type [H, 12 and 13, 15, 25, 40, 4T ] ... [Pg.1050]

A3.13.3.2 THE MASTER EQUATION FOR COLLISIONAL AND RADIATIVE ENERGY REDISTRIBUTION UNDER CONDITIONS OF GENERALIZED FIRST-ORDER KINETICS... [Pg.1050]

There is one special class of reaction systems in which a simplification occurs. If collisional energy redistribution of some reactant occurs by collisions with an excess of heat bath atoms or molecules that are considered kinetically structureless, and if fiirthennore the reaction is either unimolecular or occurs again with a reaction partner M having an excess concentration, dien one will have generalized first-order kinetics for populations Pj of the energy levels of the reactant, i.e. with... [Pg.1050]

Collisional energy transfer in molecules is a field in itself and is of relevance for kinetic theory (chapter A3.1). gas phase kmetics (chapter A3.4). RRKM theory (chapter A3.12). the theory of unimolecular reactions in general,... [Pg.1053]

The standard mechanisms of collisional energy transfer for both small and large molecules have been treated extensively and a variety of scaling laws have been proposed to simplify the complicated body of data [58, 59, 75]. To conclude, one of the most efficient special mechanisms for energy transfer is the quasi-reactive process involving chemically bound intennediates, as in the example of the reaction ... [Pg.1055]

Lenzer T, Luther K, Troe J, Gilbert R G and Urn K F 1995 Trajectory simulations of collisional energy transfer in highly excited benzene and hexafluorobenzene J. Chem. Phys. 103 626-41... [Pg.1086]

Grigoleit U, Lenzer T and Luther K 2000 Temperature dependence of collisional energy transfer in highly excited aromatics studied by classical trajectory calculations Z. Phys. Chem., A/F214 1065-85... [Pg.1086]

Miller L A and Barker J R 1996 Collisional deactivation of highly vibrationally excited pyrazine J. Chem. Phys. 105 1383-91... [Pg.1086]

Hippier H, Troe J and Wendelken H J 1983 Collisional deactivation of vibrationally highly excited polyatomic molecules. II. Direct observations for excited toluene J. Chem. Phys. 78 6709... [Pg.1086]

Hold U, Lenzer T, Luther K, Reihs K and Symonds A C 2000 Collisional energy transfer probabilities of highly excited molecules from kinetically controlled selective ionization (KCSI). I. The KCSI technique experimental approach for the determination of P(E, E) in the quasicontinuous energy ranged. Chem. Phys. 112 4076-89... [Pg.1086]

High-resolution spectroscopy used to observe hyperfme structure in the spectra of atoms or rotational stnicture in electronic spectra of gaseous molecules connnonly must contend with the widths of the spectral lines and how that compares with the separations between lines. Tln-ee contributions to the linewidth will be mentioned here tlie natural line width due to tlie finite lifetime of the excited state, collisional broadening of lines, and the Doppler effect. [Pg.1143]

Spectral lines are fiirther broadened by collisions. To a first approximation, collisions can be drought of as just reducing the lifetime of the excited state. For example, collisions of molecules will connnonly change the rotational state. That will reduce the lifetime of a given state. Even if die state is not changed, the collision will cause a phase shift in the light wave being absorbed or emitted and that will have a similar effect. The line shapes of collisionally broadened lines are similar to the natural line shape of equation (B1.1.20) with a lifetime related to the mean time between collisions. The details will depend on the nature of the intemrolecular forces. We will not pursue the subject fiirther here. [Pg.1144]

Pibel C D, Sirota E, Brenner J and Dai H L 1998 Nanosecond time-resolved FTIR emission spectroscopy monitoring the energy distribution of highly vibrationally excited molecules during collisional deactivation J. Chem. Phys. 108 1297-300... [Pg.1176]

Figure Bl.7.7. Summary of the other collision based experiments possible with magnetic sector instruments (a) collision-mduced dissociation ionization (CIDI) records the CID mass spectrum of the neutral fragments accompanying imimolecular dissociation (b) charge stripping (CS) of the incident ion beam can be observed (c) charge reversal (CR) requires the ESA polarity to be opposite that of the magnet (d) neutiiralization-reionization (NR) probes the stability of transient neutrals fonned when ions are neutralized by collisions in the first collision cell. Neutrals surviving to be collisionally reionized in the second cell are recorded as recovery ions in the NR mass spectrum. Figure Bl.7.7. Summary of the other collision based experiments possible with magnetic sector instruments (a) collision-mduced dissociation ionization (CIDI) records the CID mass spectrum of the neutral fragments accompanying imimolecular dissociation (b) charge stripping (CS) of the incident ion beam can be observed (c) charge reversal (CR) requires the ESA polarity to be opposite that of the magnet (d) neutiiralization-reionization (NR) probes the stability of transient neutrals fonned when ions are neutralized by collisions in the first collision cell. Neutrals surviving to be collisionally reionized in the second cell are recorded as recovery ions in the NR mass spectrum.
Ar, Cs, Ga or other elements with energies between 0.5 and 10 keV), energy is deposited in the surface region of the sample by a collisional cascade. Some of the energy will return to the surface and stimulate the ejection of atoms, ions and multi-atomic clusters (figure Bl.25.8). In SIMS, secondary ions (positive or negative) are detected directly with a mass spectrometer. [Pg.1860]

Inelastic scattering produces a pennanent change in the internal energy and angrilar momentum state of one or both structured collision partners A and B, which retain their original identity after tire collision. For inelastic = (a, P) — /= (a, P ) collisional transitions, tlie energy = 1 War 17 of relative motion, before ( ) and after... [Pg.2007]

A distributiony (v ) of NM) test particles (cm of species A in a beam collisionally interacts with a distribution of N () field particles of species B. Collisions with B will scatter A out of the beam at the... [Pg.2009]

Optical metiiods, in both bulb and beam expermrents, have been employed to detemiine tlie relative populations of individual internal quantum states of products of chemical reactions. Most connnonly, such methods employ a transition to an excited electronic, rather than vibrational, level of tlie molecule. Molecular electronic transitions occur in the visible and ultraviolet, and detection of emission in these spectral regions can be accomplished much more sensitively than in the infrared, where vibrational transitions occur. In addition to their use in the study of collisional reaction dynamics, laser spectroscopic methods have been widely applied for the measurement of temperature and species concentrations in many different kinds of reaction media, including combustion media [31] and atmospheric chemistry [32]. [Pg.2071]

Many optical studies have employed a quasi-static cell, through which the photolytic precursor of one of the reagents and the stable molecular reagent are slowly flowed. The reaction is then initiated by laser photolysis of the precursor, and the products are detected a short time after the photolysis event. To avoid collisional relaxation of the internal degrees of freedom of the product, the products must be detected in a shorter time when compared to the time between gas-kinetic collisions, that depends inversely upon the total pressure in the cell. In some cases, for example in case of the stable NO product from the H + NO2 reaction discussed in section B2.3.3.2. the products are not removed by collisions with the walls and may have long residence times in the apparatus. Study of such reactions are better carried out with pulsed introduction of the reagents into the cell or under crossed-beam conditions. [Pg.2080]


See other pages where Collisional is mentioned: [Pg.226]    [Pg.799]    [Pg.799]    [Pg.806]    [Pg.816]    [Pg.859]    [Pg.872]    [Pg.1045]    [Pg.1046]    [Pg.1046]    [Pg.1047]    [Pg.1050]    [Pg.1051]    [Pg.1053]    [Pg.1145]    [Pg.1244]    [Pg.1338]    [Pg.1342]    [Pg.2020]    [Pg.2024]    [Pg.2059]    [Pg.2060]   


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Anion sensors based on collisional quenching

Chemical collisional

Collisional Activation in an Ion Trap

Collisional Contributions to Braginskii Equations

Collisional Coupling to Embedded Particles

Collisional KE

Collisional Narrowing of Lines

Collisional Quenching the Stern-Volmer Relation

Collisional Rate of Change

Collisional Rate of Change Derivate Flux and Source Terms

Collisional Transfer of Electronic Energy

Collisional activated decomposition

Collisional activated decomposition spectrum

Collisional activation

Collisional activation and deactivation (

Collisional activation and reaction

Collisional activation experiments

Collisional activation experiments ionization

Collisional activation experiments protonation

Collisional activation mass spectrometry

Collisional activation process

Collisional activation spectra

Collisional activation spectroscopy

Collisional alignment

Collisional alignment and orientation

Collisional and Static Contact Electron Transfer in DNA

Collisional association

Collisional bandwidth

Collisional broadening

Collisional charge inversion

Collisional complexes

Collisional cooling

Collisional cross section 3 + 3] conditions

Collisional damping

Collisional de-excitation

Collisional deactivation of vibrationally

Collisional deactivation, inefficient

Collisional decay

Collisional deexcitation

Collisional depopulation

Collisional depopulation electrons

Collisional depopulation molecules

Collisional detachment

Collisional dipole

Collisional dissociation

Collisional dynamics

Collisional effects

Collisional efficiency

Collisional electron detachment

Collisional electron release

Collisional electron transfer

Collisional electronic relaxation processes

Collisional energy transfer magnitude

Collisional energy transfer quenching

Collisional excitation

Collisional fluorescence quenching

Collisional focusing

Collisional force

Collisional fragmentation

Collisional frequency

Collisional granites

Collisional growth theory

Collisional heat transfer

Collisional heat transfer coefficient

Collisional invariants

Collisional ionisation

Collisional ionization

Collisional ionization electron attachment

Collisional ionization rotational excitation

Collisional line width

Collisional mechanisms

Collisional mixing

Collisional model

Collisional momentum transfer

Collisional narrowing

Collisional neutralization

Collisional orientation

Collisional pair distribution function

Collisional polarization

Collisional polarization transfer

Collisional population transfer

Collisional processes

Collisional quenching, kinetics

Collisional radiative model

Collisional radiative recombination

Collisional randomization

Collisional rates

Collisional redistribution

Collisional relaxation

Collisional relaxation constants

Collisional relaxation time

Collisional resonances

Collisional resonances atoms

Collisional resonances molecules

Collisional stabilization

Collisional stabilization reaction

Collisional tectonic setting

Collisional time delay

Collisional trajectories

Collisional transfer

Collisional transfer of momentum and

Collisional transfer of momentum and energy

Collisional triplet quenching

Collisional vibrational relaxation processes

Collisional-flux term

Collisional-flux term density

Collisional-induced decomposition

Collisional-induced dissociation

Collisionally FTICR

Collisionally activated

Collisionally activated decomposition

Collisionally activated decompositions (CAD

Collisionally activated dissociation

Collisionally activated dissociation spectra

Collisionally induced

Collisionally induced dissociation

Collisionally induced dissociation spectra

Collisionally peptides

Collisionally polymers

Countering collisional effects

Cross sections collisional

Deactivation, collisional

Decoherence collisional

Electronic absorption spectra excitation, collisional

Electronic relaxation, collisional effects

Energy collisional

Energy collisional, from excited

Energy flux, collisional contribution

Energy transfer collisional

Enhancements of the Collisional Verlet Method

Equilibrium collisional ionization

Excited ions collisional deactivation

Excited ions collisional dissociation

Excited state, collisional quenching

Experimental Evidence for the Formation of Fullerenes by Collisional

Fluorescence collisional effects

Fluorescence collisionally induced

Fluorescence quenching collisional mechanisms

Friction collisional

Granular flow collisional pressure

Hydrogen collisional deactivation

Inelastic collisional transitions

Integral cross sections, collisional

Ion trap collisional activation

Ions, collisional cooling

Light-induced collisional energy

Light-induced collisional energy transfer

Line broadening collisional

Line collisional

Mass spectrometry collisionally activated dissociation

Molecular Hydrogen and Collisional-Radiative Modeling

Molecule collisional

Multiple excitation collisional activation

Neutral collisional activation

Nitrogen, collisional deactivation

Other Collisional Quenchers

Penning ionization collisional

Photon-Assisted Collisional Energy Transfer

Processes collisional vibrational

Pump-and-Probe Spectroscopy of Collisional Relaxation in Liquids

Quenching, collisional

Radiation redistribution, collisional

Reaction complex collisional stabilization

Relaxation, collisional quenching

Relaxation, collisional quenching vibrational

Rydberg collisional

Rydberg levels collisional

Sensing Based on Collisional Quenching of Fluorescence

Sensing collisional

Shear Viscosity of SRD Collisional Contribution

Shear viscosity collisional contribution

Spectra, molecular collisional broadening

Spectrometry collisionally induced

Spectroscopy collisional energy transfer

Stress collisional

Threshold energy collisional ionization

Transport coefficients collisional contribution

Triplet energy transfer, collisional

Triplet energy transfer, collisional rates

Velocity collisional

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