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Author: Kenneth N. C. Bray Publisher: ISBN: Category : Molecular dynamics Languages : en Pages : 68
Book Description
The vibrational relaxation of a system of anharmonic oscillator molecules was analysed, by a moment method. Exchange of vibrational energy between molecules was included, and plays an important part in the relaxation mechanism. Calculations for nitrogen show that, during vibrational excitation, the relaxation rate is only slightly different from that predicted by Landau and Teller, for harmonic oscillator molecules. However, very rapid vibrational de-excitation is found to occur, under conditions far from equilibrium. This is a result of a build-up of upper level vibrational populations, fed by rapid vibration-vibration exchanges. (Author).
Author: Kenneth N. C. Bray Publisher: ISBN: Category : Molecular dynamics Languages : en Pages : 68
Book Description
The vibrational relaxation of a system of anharmonic oscillator molecules was analysed, by a moment method. Exchange of vibrational energy between molecules was included, and plays an important part in the relaxation mechanism. Calculations for nitrogen show that, during vibrational excitation, the relaxation rate is only slightly different from that predicted by Landau and Teller, for harmonic oscillator molecules. However, very rapid vibrational de-excitation is found to occur, under conditions far from equilibrium. This is a result of a build-up of upper level vibrational populations, fed by rapid vibration-vibration exchanges. (Author).
Author: J. W. Rich Publisher: ISBN: Category : Oscillators, Transistor Languages : en Pages : 102
Book Description
The terms in the master equation for vibrational relaxation of anharmonic oscillators are ordered according to the rates of the relaxation processes (vibrational exchange, vibrational-energy transfer to translation). A perturbation procedure is developed by making use of the fact that the vibration-translation energy exchange transitions are much slower than the vibration-vibration transitions. The population distributions in the master equation are expanded about their values when the vibration-vibration mechanism is the only one present. To zeroth order, the master equation is satisfied by a distribution derived previously by Treanor for anharmonic oscillators. This distribution is maintained by vibration-vibration exchange, and is only Boltzmann during relaxation in the limit of vanishing anharmonicity. The perturbation on this distribution, created by vibration energy transfer to translation, is calculated to first order for a special case. The relaxation of the first moment of the zeroth-order distribution function is also investigated. The population of the lowest vibrational states can be considerably lower than the population predicted by the Landau-Teller model for the relaxation process. Furthermore, since the inversion tends to weight those states having fast vibration-to-translation energy transfer rates, the overall energy relaxation rate can be accelerated. (Author).
Author: Robert L. McKenzie Publisher: ISBN: Category : Gas dynamics Languages : en Pages : 36
Book Description
The set of master rate equations for the vibrational relaxation of mixtures of anharmonic diatomic gases in supersonic nozzle expansions is integrated numerically. Large deviations from a Boltzmann distribution of vibrational state population are predicted, particularly when vibrational energy is exchanged between two near-resonant diatomic species. Radiative gain coefficients for nonequilibrium vibration-rotation transitions are also computed and positive gains, sufficient to support laser oscillations, are predicted for CO-N2 and CO-N,-Ar admixtures.
Author: A. W. Ali Publisher: ISBN: Category : Languages : en Pages : 32
Book Description
The theory of the vibrational energy relaxation and dissociation of the nitrogen molecule is formulated. The appropriate rates are developed for the harmonic (HO) and anharmonic oscillator (AHO) models. Specifically, a V-T rate for T
Author: Mario Capitelli Publisher: Springer Science & Business Media ISBN: 3642486150 Category : Science Languages : en Pages : 354
Book Description
This book is devoted to the systematic treatment of nonequi 1 ibrium vibrational kinetics in molecular systems. Particular emphasis is given to the vibrational excitation of diatomic molecules by low-energy electrons in a discharge and by IR photons in laser-pumped systems. The book follows the different steps of the introduction, redistribution, loss, and chemical conversion of the vibrational quanta, from the points of view of the overall kinetics and the dynamics of elementary processes. These two aspects are balanced in a multidisciplinary approach. The different chapters give the basic instruments (theoretical and experimental) which are needed to understand the ki netics of nonequilibrium systems. The book will introduce the reader to different areas such as plasmachemistry, laser chemistry, IR and Raman spectroscopy, and relaxation phenomena, emphasizing how the vibrational energy affects such research fields. The chapters dedicated to collisional dynamics involving vibrational excited molecules provide an introduc tion to the modern techniques uti 1 ized in the scattering theory of inelastic and reactive collisions. The extension of the vibrational kinetics to polyatomic mole cules, discussed in Chap. 10, is the natural bridge between coll ision and coll i sionless regimes. In conclusion, we hope that the approach followed in this book will stimulate the collaboration of researchers coming from different research fields, which are too often completely separate.
Author: Robert L. McKenzie Publisher: ISBN: Category : Gas dynamics Languages : en Pages : 24
Book Description
The set of master rate equations for the vibrational relaxation of mixtures of anharmonic diatomic gases in supersonic nozzle expansions is integrated numerically. Large deviations from a Boltzmann distribution of vibrational state population are predicted, particularly when vibrational energy is exchanged between two near-resonant diatomic species. Radiative gain coefficients for nonequilibrium vibration-rotation transitions are also computed and positive gains, sufficient to support laser oscillations, are predicted for CO-N2 and CO-N, -Ar admixtures.
Author: Kenneth N. C. Bray
Author: Kenneth N. C. Bray
Author: J. W. Rich
Author: Robert L. McKenzie
Author: A. W. Ali
Author: Mario Capitelli
Author: Charles E. Treanor
Author: Anthony A. Boiarski
Author: Robert L. McKenzie
Author: Lowell Dean McMillen
Author: Francis Hugh Maillie