My research involves the study of combustion and pyrolysis reactions at very high temperatures. The purpose of this work is to provide a database for the modeling and optimization of practical combustion systems and for "steam crackers" --- noncatalytic pyrolysis reactors for the conversion of saturated hydrocarbons to olefins --- which are widely used in the petrochemical industry.
To observe chemical reaction at very high temperatures I use a device called a shock tube, a kind of supersonic plug-flow reactor that acts as an instantaneous, completely homogeneous furnace, with arbitrary and externally set temperatures. We use very fast laser techniques, call laser- schlieren and laser flash absorption, to observe the very rapid chemical reactions (usually lasting less than ten microseconds) in the shock wave. In fact, our methods allow us to study these reactions at higher temperatures than is possible with any other technique.
One recent achievement has been the proof that vinylacetylene (C4H4) dissociates directly to two acetylene molecules, showing that two acetylenes can thus dimerize directly to vinylacetylene, an important reaction often postulated but never previously demonstrated.
"Rate of CH4 Dissociation over 2800-4300K: The Low-Pressure-Limit Rate Constant", J.H. Kiefer and S.S. Kumaran, J. Phys. Chem. 97, 414 (1993).
"The Importance of Hindered Rotations and other Anharmonic Effects in the Thermal Dissociation of Small Unsaturated Molecules: Application to HCN", A.F. Wagner and J.H. Kiefer, 24th Symposium (Int'l) on Combustion, Sydney, 1992, pg. 613.
"The Formaldehyde Decomposition Chain Mechanism", E.A. Irdam, J.H. Kiefer, L.B. Harding and A.F. Wagner, Int. J. Chem. Kinet., 25, 285 (1993).
"Thermal Dissociation Studies of Toluene at High Temperatures", R.D. Kern, H. Chen, H.J. Singh, K. Xie, J.H. Kiefer and S.S. Sidhu, Proc. 6th Toyota Conference on Turbulence and Molecular Processes in Combustion, T. Takeno, Ed. Elsevier Amsterdam, (1993) pg. 117.
"The Thermal Decomposition of Carbon Tetrachloride", J.V. Michael, K.P. Lin, S.S. Kumaran and J.H. Kiefer, J. Phys. Chem. 97, 1914 (1993).
Comment: "Radical Processes in the Pyrolysis of Acetylene", J.H. Kiefer, Int. J. Chem. Kinet. 25, 215 (1993).
"Vibrational Relaxation, Dissociation, and Dissociation Incubation Times in Norbornene", J.H. Kiefer, S.S. Kumaran, and S. Sundaram, J. Chem. Phys. 99, 3531 (1993).
"The Mutual Isomerization of Allene and Propyne", J.H. Kiefer, S.S. Kumaran, and P.S. Mudipalli, Chem. Phys. Lett., 224, 51 (1994).
"Thermal Decomposition of Propargyl Bromide and the Subsequent Formation of Benzene", R.D. Kern, H. Chen, J.H. Kiefer, and P.S. Mudipalli (Accepted for presentation and publication in the 25th Symp. (Int'l) on Combustion, Irvine, CA; July 1994.)
"The Themal Decomposition of CF3Cl", J.H. Kiefer, R. Sathyanarayana, K.P. Lim, and J.V. Michael, J. Phys. Chem., accepted.
"Unimolecular Reactions at High Temperatures", W. Tsang and J.H. Kiefer, invited chapter for the volume: "The Chemical Dynamics and Kinetics of Small Radicals", K. Liu and A.F. Wagner; Eds., Springer-Verlag, in press.
Invited Introduction to the volume: "Physico-Chemical Processes and Nonequilibrium Flows", proceedings of the 19th Symposium on Shock Waves and Shock Tubes, Marsielle 1993. To be published by Springer. (in press)