Theory of Unimolecular Reactions - 1st Edition - ISBN: 9780122623509, 9780323149358

Theory of Unimolecular Reactions

1st Edition

Authors: Wendell Forst
eBook ISBN: 9780323149358
Imprint: Academic Press
Published Date: 28th January 1973
Page Count: 464
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Theory of Unimolecular Reactions provides a comprehensive analysis of the theory of unimolecular reactions, also known to kineticists as the Rice-Marcus or the Rice-Ramsperger-Kassel-Marcus theory, and to those working in mass spectrometry and related fields as the quasi-equilibrium theory or the theory of mass spectra. This book demonstrates how theoretical parameters are related to experimental observables and describes the methods that are used to obtain useful numerical answers. This monograph consists of 11 chapters and begins by explaining the derivation of the expression for the basic rate k(E), with emphasis on the unimolecular rate constant, intramolecular energy transfer, and potential energy surfaces in unimolecular reactions. The statistical calculation of unimolecular rate under vibrational potential is also given, along with pertinent degrees of freedom. The remaining chapters explore the energy distribution functions appropriate to each system, the averaging of k(E), and the relations between theoretical and experimental parameters. Thermal reactions, chemical activation systems, and the theory of mass spectra are examined. The last chapter is devoted to the transition state and its ambiguities. This text will be of interest to gas kineticists, mass spectrometrists, and students and researchers working in the field of physical chemistry.

Table of Contents




Part I Introduction

Chapter 1. The Unimolecular Rate Constant

1. The Unimolecular Process

2. Decay of a Pure Bound State into a Single Channel

3. Average Rate

4. Average Lifetime

5. Basic Assumption



Chapter 2. Intramolecular Energy Transfer

1. Theory of Slater

2. Theory of Rice, Ramsperger, and Kassel

3. Intramolecular Energy Transfer

4. Randomization of Energy and Experimental Evidence

5. Theoretical Treatment of Energy Randomization

6. The Rice-Marcus (RRKM) Theory


Chapter 3. Potential Energy Surfaces in Unimolecular Reactions

1. Triatomic Potential Energy Surface for a Vibrational Potential

2. Triatomic Potential Energy Surfaces for an Effective Potential

3. Triatomic Potential Energy Surfaces for Nonadiabatic Reactions

4. Extrapolation to Polyatomic Potential Energy Surfaces


Chapter 4. Statistical Calculation of Unimolecular Rate under Vibrational Potential

1. Unimolecular Process in Classical Phase Space

2. The Quantum-Mechanical Unimolecular Rate Constant

3. An Alternative Derivation

4. Nonclassical Effects Near Potential Barrier Maximum

5. Reaction Path Degeneracy



Chapter 5. Pertinent Degrees of Freedom

1. Degrees of Freedom Excluded by Conservation Requirements

2. Internal Degrees of Freedom

3. External Degrees of Freedom

4. Model for Particle


Chapter 6. Calculation of Energy-Level Densities

1. Terminology and Basic Concepts

2. Direct Evaluation of W(E) and G{E) in Simple Systems

3. Approximation to N(E) and G(E): General Considerations

4. Inversion of the Partition Function

5. Approximation to N(E) and G(E) for Rotational States

6. Direct Evaluation of Nvr(E) and Gvr(E) in Simple Systems

7. Approximations Based on Inversion of Classical Partition Function

8. Approximations Based on the Inversion of the Quantum-Mechanical Partition Function

9. Approximation to Nvr(E) and Gyr(E) for more Realistic Systems

10. Conclusions



Chapter 7. Unimolecular Rate with an Effective Potential

1. The Rotational Potential

2. Type 1 Vibrational Potential

3. Effective Potential for Type 1 Reaction

4. Effective Potential for Type 2 and Type 3 Reactions



Part II Introduction

Chapter 8 Thermal Reactions

1. Collisional Activation: General Features of Lindemann's Simple Mechanism

2. Averaging over Equilibrium Distribution

3. Averaging over Steady-State Distribution

4. Evaluation of Centrifugal Correction Factors

5. Pressure Dependence

6. Temperature Dependence

7. Theoretical Parameters and Experimental Observables

8. Generalized Lindemann's Mechanism and the Nonequilibrium Distribution



Chapter 9 Chemical Activation Systems

1. Nature of Chemical Activation

2. Determination of the Energy Distribution Function

3. Pressure Dependence of Rate

4. Temperature Dependence of Rate

5. Collisional Deactivation in a Multilevel System

6. Photo-activation

7. Theoretical Parameters and Experimental Observables

8. Centrifugal Effects



Chapter 10 Fragmentation of Highly Excited Species: Theory of Mass Spectra

1. Unimolecular Reactions of Positive Ions

2. Consecutive-Parallel Reactions: Energy Partitioning

3. Production of Ionized Species

4. Potential Energy Surfaces of Polyatomic Ions

5. Randomization of Electronic Energy

6. Determination of Energy Distribution Function

7. Primary Yield in Radiolysis

8. Theoretical Parameters and Experimental Observables

9. Kinetic Energy of Fragments and Rotational Effects



Chapter 11 Transition States in Unimolecular Reactions

1. General Remarks; Isotope Effect

2. Transition States for Type 1 Reactions

3. Transition States for Type 2 Reactions

4. Transition States for Type 3 Reactions




List of Symbols

Author Index

Subject Index


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Academic Press
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About the Author

Wendell Forst

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