Non-equilibrium kinetics in natural phenomena
An essentially universal assumption of chemical kinetics in combustion, atmospheric and many other environments is that bimolecular reactions only occur between reactants of rovibrational energy described by a Boltzmann (thermal) distribution. In other words, if an ensemble of molecules is initially formed with an energy distribution that differs from the Boltzmann distribution (non-Boltzmann), as is relatively commonplace, the molecular ensemble is assumed to undergo sufficiently many energy-transferring (thermalizing) collisions to establish a Boltzmann distribution prior to subsequent bimolecular reaction.
Given that fuel and oxygen mole fractions comprise a substantial fraction of fuel/air mixtures under practical, full-strength combustion conditions and that oxygen constitutes ~20% of air, there is significant potential for molecular ensembles to undergo reactive collisions on the same time scale as thermalizing collisions in both combustion and atmospheric systems. The potential for such a phenomenon calls to question the abovementioned Boltzmann distribution assumption and provides possibilities for entirely different kinetics processes to dominate oxidation behavior.
Our group is developing quantitative computational strategies to model these processes and applying them to understand ways how they influence the controlling pathways in a variety of natural phenomena.
M.P. Burke, C.F. Goldsmith, S.J. Klippenstein, O. Welz, H. Huang, I.O. Antonov, J.D. Savee, D.L. Osborn, J. Zádor, C.A. Taatjes, L. Sheps, "Multiscale Informatics for Low-Temperature Propane Oxidation: Further Complexities in Studies of Complex Reactions," Journal of Physical Chemistry A 119 (2015) 7095-7115, http://dx.doi.org/10.1021/acs.jpca.5b01003.
M.P. Burke, C.F. Goldsmith, Y. Georgievskii, S.J. Klippenstein, "Towards a Quantitative Understanding of the Role of Non-Boltzmann Reactant Distributions in Low-Temperature Oxidation," Proceedings of the Combustion Institute 35 (2015) 205–213, http://dx.doi.org/10.1016/j.proci.2014.05.118.
C.F. Goldsmith, M.P. Burke, Y. Georgievskii, S.J. Klippenstein, "Effect of Non-Thermal Product Energy Distributions on Ketohydroperoxide Decomposition Kinetics," Proceedings of the Combustion Institute 35 (2015) 283-290, http://dx.doi.org/10.1016/j.proci.2014.05.006.
Y. Georgievski, J.A. Miller, M.P. Burke, S.J. Klippenstein, "Reformulation and Solution of the Master Equation for Multiple-Well Chemical Reactions," Journal of Physical Chemistry A 117 (2013) 12146-12154, http://dx.doi.org/10.1021/jp4060704.
Y. Georgievskii, A.W. Jasper, J. Zádor, J.A. Miller, M.P. Burke, C.F. Goldsmith, S.J. Klippenstein, PAPER (A Master Equation Code), v1, (2014) unpublished.
Relevant conference presentations
M.P. Burke, "Collisional Energy Transfer during Complex Reactions in Multi-Component Mixtures," 9th International Conference on Chemical Kinetics, Ghent, Belgium, July 2015 (contributed).
M.P. Burke, "The Role of Model Structural Uncertainties in Uncertainty Quantification and Experimental Design," 9th U.S. Meeting of the Combustion Institute, Cincinnati, Ohio, May 2015 (contributed).
M.P. Burke, "Multi-Scale Informatics for Low-Temperature Oxidation," 2nd International Workshop on Flame Chemistry, San Francisco, California, August 2014 (invited).
M.P. Burke (with C.F. Goldsmith, Y. Georgievskii, S.J. Klippenstein), "Towards a Quantitative Understanding of the Role of Non-Boltzmann Reactant Distributions in Low-Temperature Oxidation," 35th International Symposium on Combustion, San Francisco, California, August 2014 (contributed).
M.P. Burke (with C.F. Goldsmith, Y. Georgievskii, S.J. Klippenstein), "Non-Boltzmann Effects in Low-Temperature Fuel Oxidation," Eastern States Meeting of the Combustion Institute, Clemson, South Carolina, October 2013 (contributed).
M.P. Burke (with C.F. Goldsmith, S.J. Klippenstein, L. Sheps, O. Welz, J. Zádor, H. Huang, C.A. Taatjes), "Multi-Scale Informatics for Low-Temperature Propane Oxidation," 8th U.S. Meeting of the Combustion Institute, Park City, Utah, May 2013 (contributed).