NON-STEADY-STATE DYNAMICS IN HIGH-TEMPERATURE SYSTEMS

Values of rate coefficients of uni- and bimolecular reactions at high temperatures are important for understanding basic processes in shock tubes and combustion systems. The usual procedure for deciphering a kinetic scheme of a high-temperature process is to solve a matrix of coupled differential equations representing the rate equations with rate coefficients which are functions of temperature alone. Time-independent rate coefficients for unimolecular (or bimolecular) reactions imply a steady-state distribution of reactants during the reaction. This is certainly true at low temperatures but, as the present work shows, fails badly at high temperatures. The consequence of this failure is decay curves which deviate significantly from the ones obtained from constant rate coefficients. We show samples of such behavior for cyclobutene isomerization and cyclobutane fission.