Theory of thermal unimolecular reactions at low pressures. I. Solutions of the master equation

The master equation for a thermal unimolecular reaction in gases at low pressures is formulated. Steady‐state solutions are derived in analytical form with an exponential model of collisional transition probabilities, (i) for vibrational energy transfer in molecules with variable densities of states, and (ii) for combined rotational and vibrational energy transfer in molecules with variable heights of the centrifugal barriers. Other models of transition probabilities are treated numerically. The diffusion limit of energy transfer is discussed. In all cases, the nonequilibrium populations of excited states and the weak collision efficiency factors βc are calculated.

[1]  J. Troe.  Theory of thermal unimolecular reactions at low pressures. II. Strong collision rate constants. Applications , 1977 .

[2]  M. Quack,et al.  Unimolecular Processes V: Maximum Free Energy Criterion for the High Pressure Limit of Dissociation Reactions , 1977 .

[3]  M. Quack,et al.  A spectroscopic determination of the methyl radical recombination rate constant in shock waves , 1976 .

[4]  H. Bergh,et al.  Kinetic and thermodynamic properties of INO and INO2 intermediate complexes in iodine recombination , 1976 .

[5]  Ian W. M. Smith,et al.  Rate measurements of reactions of OH by resonance absorption. Part 5.—Rate constants for OH + NO2(+M)→ HNO3(+M) over a wide range of temperature and pressure , 1976 .

[6]  R. Berry,et al.  Theory of Elementary Atomic and Molecular Processes in Gases , 1975 .

[7]  W. Forst,et al.  Transfer of vibrational-rotational energy in thermal reactions: approximations, application to diatomics , 1975 .

[8]  M. Quack,et al.  Complex Formation in Reactive and Inelastic Scattering: Statistical Adiabatic Channel Model of Unimolecular Processes III , 1975 .

[9]  S. Rice,et al.  A quantum ergodic theory approach to unimolecular fragmentation , 1975 .

[10]  C. Ottinger,et al.  Rotation-vibration-translation energy transfer in laser excited Li2 (B1Πu) , 1974 .

[11]  W. Jost,et al.  Physical Chemistry, An Advanced Treatise , 1974 .

[12]  D. C. Tardy,et al.  Theory of Unimolecular Reactions , 1973 .

[13]  P. J. Robinson.  Unimolecular reactions , 1972 .

[14]  G. E. Leroi,et al.  Energy‐Transfer Processes in Monochromatically Excited Iodine Molecules. V. Rotational Energy Transfer in Argon‐Excited I2 , 1971 .

[15]  J. Steinfeld,et al.  Energy‐Transfer Processes in Monochromatically Excited Iodine Molecules. III Quenching and Multiquantum Transfer from υ′ = 43 , 1970 .

[16]  J. Keck.  Generalized Diffusion Theory of Nonequilibrium Reaction Rates , 1967 .

[17]  B. Rabinovitch,et al.  Collisional Energy Transfer. Thermal Unimolecular Systems in the Low‐Pressure Region , 1966 .

[18]  James C. Keck,et al.  DIFFUSION THEORY OF NONEQUILIBRIUM DISSOCIATION AND RECOMBINATION , 1965 .

[19]  T. A. Bak,et al.  Hard‐Sphere Model for the Dissociation of Diatomic Molecules , 1964 .

[20]  D. L. Bunker.  Monte Carlo Calculations. IV. Further Studies of Unimolecular Dissociation , 1964 .

[21]  G. Kohlmaier,et al.  Collisional Transition Probabilities for Vibrational Deactivation of Chemically Activated sec‐Butyl Radicals. The Rare Gases , 1963 .

[22]  K. Shuler,et al.  On the Relaxation of Vibrational Nonequilibrium Distributions. III. The Effect of Radiative Transitions on the Relaxation Behavior , 1957 .

[23]  C. Hinshelwood,et al.  The Kinetics of Chemical Change in Gaseous Systems , 1927, Nature.