Its basic approach is to
combine a theoretical effort in the energetics and dynamics
of chemical reactions with an experimental effort in dynamics
and kinetics under chemically isolated conditions and also
under more complex conditions in flames.contributions concerning the dynamics of chemical elementary processes.
This program studies elementary chemical reactions, related
non-reactive energy transfer processes, and coupled kinetics
processes involved in combustion. Its basic approach is to
combine a theoretical effort in the energetics and dynamics
of chemical reactions with an experimental effort in dynamics
and kinetics under chemically isolated conditions and also
under more complex conditions in flames.
The theoretical effort, involving five staff members, embraces both large-scale applications of existing theoretical methods and the development of new methods that efficiently exploit advanced computer architectures. Both electronic structure techniques that determine intermolecular forces and dynamics techniques that determine molecular responses to these forces will be pursued.
Simulations of more complex combustion environments involving coupling kinetics are also being pursued. The experimental effort, involving five staff members, encompasses state-resolved measurements in flow tubes at low temperatures, thermal reaction kinetics measurements in shock tubes at high tempertatures, photoionization measurements of thresholds and state-resolved product distributions, and in situ X-ray scattering measurements of sooting flames. Reaction rates, branching ratios (between different neutral products or between ionic and neutral products),
product distributions, the effect of initial vibrational excitation on reactivity, ion-cycles for thermochemical information, and the morphology and chemistry of soot formation can all be examined. The close coupling between theory and experiment brings a unique combination of expertise to bear on the study of chemical reactivity.
This work is designed to provide a fundamental understanding of both major and trace reactions of importance in combustion.
Many of the projects of our group involve several group members and a mixture of expertise that complicates any attempt to organize our projects by authors or by categories. Nonetheless, in the sections that follow, each of our ten staff will describe their contribution to the group's achievements. To give a flavor of the group's accomplishments, I cite here several illustrative achievements:
Our group initiated and led a theoretical/experimental multi-national-laboratory collaboration that definitively showed that the heat of formation of the OH radical has been overestimated in all standard thermochemical tables by approximately 0.5 kcal/mol.
Our group has concluded by systematic experimental measurements and supportive theoretical calculations that the recombination rate of H+O2 is an order of magnitude faster in water vapor than in other common buffer gases (e.g., rare gases, oxygen, nitrogen, or methane) because of long-range polar-polar electrostatic interactions.
Our group, in collaboration with theoretical and experimental programs at other DOE laboratories, has demonstrated that the addition-elimination process CH3+O ® H2+HCO with a barrier but no saddle point
and no steepest descent reaction path can still account for ~20% of the reaction branching ratio. This is the first documentation of a reaction that can not be modeled by reaction paths.
Utilizing state-of-the-art wave packet propagation techniques, the role of excited state and non-adiabatic dynamics in the O(1D) + H2 ® OH + H reaction was investigated. Extensive calculations, including the ground and two excited electronic states predicted the ratio of the reactive cross sections for rotationally excited and cold H2. The results disagreed with earlier experiments and motivated a new molecular beam experiment that agreed quantitatively with the theoretical predictions.
Our group has developed new ways to investigate the long-time dynamics of nonlinear master equations. This has allowed us to develop rate laws to describe association kinetics and vibrational relaxation. Applications have been made to methyl recombination and the nonlinear vibrational relaxation of oxirane. In both cases, our rate laws model the process correctly while standard rate laws break down when reactant concentrations within inert buffer gases become a few percent or higher.
Our group, in collaboration with computational scientists in the Mathematics and Computer Science Division, has developed a new general way to iteratively solve matrix eigenvalue problems. The method, called SPAM, uses projection operators and a simple matrix that approximates the exact one to accelerate the Davidson iterative method (typically used in electronic structure calculations). The method is general to all eigenvalue problems where physical insight can produce a simple approximate matrix.
Our group, in collaboration with the Carbon Chemistry group within the division, has initiated a program of in situ analysis of nano-scale soot within flames using small angle X-ray scattering (SAXS) at the Advanced Photon Source. This effort, one of the first SAXS applications in the gas-phase, has discovered detailed structure in soot distributions in laminar flames and has led to development of a prototype detector to monitor transient (e.g., droplet) flames with a time resolution of ~10 µs. Such a detector will be useful in many other areas of chemistry. Our group has carried out one of the most detailed state- to-state studies ever performed of vibrational autoionization in a polyatomic molecule, in this case ammonia.
Of all the fundamental or combination normal mode excitations tried, initial excitation of the umbrella mode is found to be the most effective in promoting autoionization and the final products of the process involve a change in either electronic symmetry or rotational quantum number depending on the specific autoionizing level.
These accomplishments and others in the research summaries to follow illustrate that our group has increasingly reached out beyond group boundaries to carry out fundamental studies in chemical reactivity.
We have always had strong experimental-theoretical interactions within the group and an active collaboration with university programs. However, in the last several years we have collaborated more intimately than before with other parts of the national laboratory system. For example, our involvement with the Carbon Chemistry group within our division is expected to be a long-term collaboration driven by a mutual interest in soot chemistry and a complementary background in experimental and theoretical expertise.
Likewise, our involvement with computational scientists in other divisions is also long-term and a recognition of the fact that computational chemistry worldwide is one of the leading consumers of computer hardware resources and both a beneficiary and a source of advanced computer software. Our involvement with other national laboratories, especially the Combustion Research Facility at Sandia National Laboratory and the Environmental Molecular Science Laboratory at Pacific Northwest National Laboratory, reflects the complementary expertise that has become centered at those laboratories. The broader involvement by the group has not only furthered our combustion research program but has also won additional funding outside of Chemical Sciences.
This additional funding includes discretionary (LDRD) funding for the soot studies and Scientific Discovery through Advanced Computing (SciDAC) funding from the Mathematics, Information, and Computer Science (MICS) office in DOE.
While different funding sources do not have identical missions, we believe the additional funding we receive will only augment and accelerate the Chemical Sciences supported program in fundamental combustion research.
In the future, our group intends to continue to pursue experimental and theoretical studies into the details of chemical reactivity manifested in combustion. We feel this is the "golden age" of combustion research in which effective coupling of experiment and theory can be achieved for increasingly complex chemical reactions that are prevalent but still poorly characterized within combustion. However,
the increasing complexity of reactions we are studying and the broader collaborations the group has become involved in suggests future group interests not exclusively tied to gas-phase processes that have been our focus in the past. For example, the soot project will involve us in cluster and agglomeration kinetics that has both gas phase and gas-surface overtones.
Furthermore, the experimental and theoretical techniques we develop for soot studies may well be applicable to studies of complex systems outside of combustion, such as molecular self-assembly or chelation kinetics. Another example of a broader study of chemical reactivity our group is involved in is a new collaboration with university researchers into reaction kinetics under carbon nanotube confinement.
While all these activities are rooted in our experience and expertise in gas phase combustion research, the research itself is leading the group to a future in which broader issues of chemical reactivity can be addressed beyond the context of combustion but within the fundamental research agenda of Chemical Sciences.
John Charles Polanyi was born in 1929 in Berlin, Germany, of Hungarian parents, Michael and Magda Elizabeth Polanyi. The family moved to England in 1933 where he received his education. His University training was at Manchester University, where he obtained his B.Sc. in 1949, and his Ph.D. in 1952.
From 1952-1954, he was a Postdoctoral Fellow at the National Research Council Laboratories in Ottawa, Canada, and from 1954-1956 Research Associate at Princeton University.
In 1956, John Polanyi was appointed as a Lecturer at the University of Toronto where he was successively Assistant Professor (1957-1960), Associate Professor (1960-1962) and Professor (1962- present). He was given the (honorific) title University Professor in January 1974.
In 1958, he married Anne (Sue) Ferrar Davidson. They have two children, Margaret Alexandra (born 1961), and Michael Ferrar (born 1963).
He serves on the Board of the Ontario Laser and Lightwave Research Centre, Canada (1988-present), is a Member of the Board of the Steacie Institute for Molecular Sciences, Canada (1991-present), and Member of the Science Advisory Board, Max Planck Institute for Quantum Optics, Germany (1982-present), and is Honorary Consultant to the Institute for Molecular Science, Okazaki, Japan (1989-1992). He was a Founding Member and is currently President of the Canadian Committee of Scientists and Scholars, and also was a Founding Member of The Royal Society of Canada Committee on Scholarly Freedom, a Member of the American Academy of Arts and Science Committee on International Security Studies, and a Member of the Board of the Canadian Centre for Arms Control and Disarmament to which he is currently an Advisor.
He was awarded the Marlow Medal of the Faraday Society 1962, Centenary Medal of the British Chemical Society 1965, the Steacie Prize for Natural Sciences (shared with N. Bartlett) 1965, the Noranda Award of the Chemical Institute of Canada 1967, the Henry Marshall Tory Medal of the Royal Society of Canada 1977, the Wolf Prize in Chemistry (shared with G. Pimentel) 1982, the Izaak Walton Killam Memorial Prize 1988, the Royal Medal of the Royal Society of London 1989, and the John C. Polanyi Lecture Award of the Canadian Society for Chemistry 1992.
He is a Fellow of the Royal Society of Canada (1966), and the Royal Society of London (1971), a Member of the American Academy of Arts and Sciences, (1976), the U.S. National Academy of Sciences (1978), the Pontifical Academy of Rome (1986), a Fellow of the Royal Society of Edinburgh (1988), an Honorary Fellow of the Royal Society of Chemistry of the United Kingdom (1991), and of the Chemical Institute of Canada (1991).
He has been the recipient of honorary degrees from the Universities of Waterloo 1970; Memorial 1976; McMaster 1977; Trent 1977; Carleton 1981; Harvard 1982; Dalhousie 1983; Rensselaer 1984; Brock 1984; St. Francis Xavier 1984; Lethbridge 1987; Victoria 1987; Ottawa 1987; Sherbrooke 1987; Laval 1987; York 1988; Manchester, England 1988; Montreal 1989, Acadia 1989; Weizmann Institute, Israel 1989; Bari, Italy 1990; British Columbia 1990; Concordia 1990, McGill 1990 and Queen's 1992.
He was made an Officer of the Order of Canada in 1974, and a Companion of the Order of Canada in 1979.
In addition to his scientific papers he has published approximately one hundred articles on science policy, on the control of armaments and the impact of science on society. He has produced a film 'Concepts in Reaction Dynamics' (1970), and has co-edited a book, 'The Dangers of Nuclear War' (1979)