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Theoretical calculations of rate‐determining steps for ignition of shocked, condensed nitromethane
Author(s) -
Bardo Richard D.
Publication year - 1986
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.560300740
Subject(s) - intermolecular force , intramolecular force , nitromethane , chemistry , chemical physics , molecule , internal energy , energy transfer , thermodynamics , ignition system , shock (circulatory) , reaction rate , coupling (piping) , chemical reaction , atomic physics , molecular physics , materials science , physics , stereochemistry , catalysis , medicine , biochemistry , organic chemistry , metallurgy
Abstract Rates of intermolecular‐to‐intramolecular energy transfer and chemical reaction were determined by quantum mechanical calculations on systems of strongly interacting molecules at high shock pressure. The energy transfer rate was estimated by utilizing a theory of radiationless transitions which describes the coupling of a sparse set of internal mode energy levels with a quasicontinuum of intermolecular mode energy levels. An important quantity in this theory is the time t pv required for activation of the internal modes. Calculated values of t pv < 1 μsec are identified with the most efficient transfer of energy when the molecules interact and react bimolecularly in the head‐to‐tail configuration. These times are consistent with those found in shock experiments and those calculated by other techniques. A comparison of t pv with chemical reaction half‐lives indicates that energy transfer and reaction alternate as rate‐determining steps over large ranges of P and T .