个人简介

Born Flushing, New York, 1959. Massachusetts Institute of Technology, B.S., 1981. University of California, Berkeley, Ph.D., 1985. University of Wisconsin, Postdoctoral Research Associate, 1985-86. The University of Chicago, Professor, 1987-. Accolades 2002 Fellow, American Physical Society. 1993 Llewellyn John and Harriet Manchester Quantrell Award for Excellence in Undergraduate Teaching, The University of Chicago. 1992 Alfred P. Sloan Fellow. 1989 Camille and Henry Dreyfus Foundation Teacher-Scholar. 1988 National Science Foundation Presidential Young Investigator. 1987 Office of Naval Research Young Investigator. 1986 Camille and Henry Dreyfus Distinguished New Faculty in Chemistry Grant.

研究领域

Physical Chemistry

Our research investigates the fundamental inter- and intramolecular forces that drive the course of chemical reactions. To experimentally probe the detailed molecular dynamics, both nuclear and electronic, during a chemical reaction we use a combination of molecular beam reactive scattering and laser spectroscopic techniques. Traditionally, predicting rate constants and microscopic dynamics has relied on statistical transition state theories or, in smaller systems, quantum scattering calculations on a single adiabatic potential energy surface that provides the barriers to each reaction. However, a reaction evolves on a single potential energy surface only if the Born Oppenheimer separation of nuclear and electronic motion is valid. Much of our recent work investigates classes of important chemical reactions where the breakdown of the Born-Oppenheimer approximation (the inability of the electronic wavefunction to readjust rapidly enough during the nuclear dynamics) near the transition state alters the dynamics and markedly reduces the reaction rate. The studies test the predictions of emerging quantum theories on nonadiabatic reaction dynamics in small systems and develop an intuitive framework for understanding chemical reaction dynamics in more complex organic and inorganic reactions not yet accessible to precise quantum calculations. As an example, our recent work on nitric acid and other important atmospheric species seeks to understand from first principles quantum mechanics why some chemical products are produced and not others. In the photodissociation of nitric acid two chemical bonds may break, producing OH+NO2 and HONO+O respectively. The ability of the electronic wavefunction to change along the reaction coordinate, particularly the orientation of the radical OH p electron's orbital, plays a critical role in determining what products are formed. Our early molecular beam experiments showed that nonadiabatic recrossing of the transition state plays a dominant role in determining the branching between chemical bond fission channels, reversing the expected branching between C-Br and C-Cl fission in the Br(CH2)nCOCl. Suppressing rapid intramolecular electronic energy transfer allows you to preferentially cleave a selected chemical bond. Our experiments and supporting ab initio calculations elucidate the intramolecular distance and conformation dependence of nonadiabatic recrossing of the reaction barriers in the competing reaction channels. Other experiments use molecular photodissociation to directly access both the upper and lower adiabatic potential energy surfaces, respectively, near the transition state region of a excited state bimolecular reaction to probe the influence of nonadiabatic coupling in chemical reaction dynamics. Our molecular beam photofragmentation and emission spectroscopy experiments and collaborative theoretical work on CH3SH investigated how accessing different regions of the CH3S + H → CH3+SH reactive potential energy surfaces changes the branching between the S-H and C-S bond fission channels and how nonadiabatic coupling influences the dynamics. In this system and in H2S, we used the technique of emission spectroscopy of dissociating molecules to investigate the dynamics which occurs during the subpicosecond dissociation event, providing a key link between the absorption spectrum and the final product quantum states. We have recently introduced a method for investigating the competing unimolecular dissociation channels of isomerically-selected radicals as a function of internal energy in the radical. Radical intermediates play a key role in a wide range of chemical processes, yet many key isomeric radical intermediates elude direct experimental probes. Our experiments photolytically produce from an appropriate precursor a selected radical isomer and disperse the radicals by their neutral velocity imparted in the photolysis, thus dispersing them by internal energy. For the unstable radicals, they then measure the branching between C-C and C-H fission products via tunable VUV photoionization of products dispersed by their velocity. This offers the unprecedented ability to measure the branching between isomeric product channels as a function of internal energy in the dissociating radical isomer on the ground state potential energy surface

近期论文

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P.-W. Lee, P. G. Scrape, L. J. Butler, and Y.-P. Lee, Two HCl-elimination Channels and Two CO-formation Channels Detected with Time-resolved Infrared Emission upon Photolysis of Acryloyl Chloride [CH2CHC(O)Cl] at 193 nm, J. Phys. Chem. A, in press (2015). M. D. Brynteson and L. J. Butler, Predicting the effect of angular momentum on the dissociation dynamics of highly rotationally excited radical intermediates, J. Chem. Phys. 142 054301 (2015). R. S. Booth and L. J. Butler, Thermal decomposition pathways for 1,1-diamino-2,2-dinitroethene (FOX-7), J. Chem. Phys., 141 134315 (2014). R. S. Booth, M. D. Brynteson, S.-H. Lee, J. J. Lin, and L. J. Butler, Further Studies into the Photodissociation Pathways of 2-Bromo-2-Nitropropane and the Dissociation Channels of the 2-Nitro-2-Propyl Radical Intermediate, J. Phys. Chem. A, 118, 4707-4722 (2014). M. D. Brynteson, C. C. Womack, R. S. Booth, S.-H. Lee, J. J. Lin, and L. J. Butler, Radical Intermediates in the Addition of OH to Propene: Photolytic Precursors and Angular Momentum Effects, J. Phys. Chem. A, DOI 10.1021/jp4108987 (2014). L. Wang, C. -S. Lam, R. Chhantyal-Pun, M. D. Brynteson, L. J. Butler, and T. A. Miller, Imaging and Scattering Studies of the Unimolecular Dissociation of the BrCH2CH2O Radical from BrCH2CH2ONO Photolysis at 351 nm, J. Phys. Chem. A, 118 404-416 (2014). B. G. McKown, M. Ceriotti, C. C. Womack, E. Kamarchik, L. J. Butler, and J. M. Bowman, Effects of High Angular Momentum on the Unimolecular Dissociation of CD2CD2OH: Theory and Comparisons with Experiment, J. Phys. Chem. A, 117 10951-63 (2013). R. S. Booth, C. -S. Lam, M. D. Brynteson, L. Wang, and L. J. Butler, Elucidating the Decomposition Mechanism of Energetic Materials with Geminal Dinitro Groups Using 2-Bromo-2-Nitropropane Photodissociation, J. Phys. Chem. A, 117 9531-9547 (2013). D. B. Straus, L. M. Butler, B. W. Alligood, and L. J. Butler, Analyzing Angular Distributions for Two-Step Dissociation Mechanisms in Velocity Map Imaging, J. Phys. Chem. A, 117 7102-7106 (2013). R. S. Booth, C. -S. Lam, and L. J. Butler, A Novel Mechanism for Nitric Oxide Production in Nitroalkyl Radicals that Circumvents Nitro-Nitrite Isomerization, J. Phys. Chem. Lett., DOI 10.1021/jz302138n (2013). DOI: 10.1021/jz302138n C. C. Womack, B. J. Ratliff, L. J. Butler, S. –H. Lee, and J. J. Lin, Photoproduct Channels from BrCD2CD2OH at 193 nm and the HDO + Vinyl Products from the CD2CD2OH Radical Intermediate, J. Phys. Chem. A, DOI 10.1021/jp21217t (2012). DOI: 10.1021/jp212167t C. C. Womack, R. S. Booth, M. D. Brynteson, L. J. Butler, and D. E. Szpunar, Characterizing the Rovibrational Distribution of CD2CD2OH Radicals Produced via the Photodissociation of 2-Bromoethanol-d4, J. Phys. Chem. A 115 14559-14569 (2011). DOI: 10.1021/jp2059694 B. W. Alligood, D. B. Straus, and L. J. Butler, Analyzing velocity map images to distinguish the primary methyl photofragments from those produced upon C-Cl bond photofission in chloroacetone at 193 nm, J. Chem. Phys. 135 034302 (2011). B. W. Alligood, C. C. Womack, D. B. Straus, F. R. Blase, and L. J. Butler, The dissociation of vibrationally excited CH3OSO radicals and their photolytic precursor, methoxysulfinyl chloride, J. Chem. Phys. 134 194304 (2011). B. J. Ratliff, B. W. Alligood, L. J. Butler, S. H. Lee, and J. J. Lin, Product Branching from the CH2CH2OH Radical Intermediate of the OH + Ethene Reaction, J. Phys. Chem. A 115 9097-9110 (2011). B. W. Alligood, C. C. Womack, M. D. Brynteson, and L. J. Butler, Dissociative photoionization of CH3C(O)CH2 to C2H5+, Int. J. Mass. Spectrom. 304 45–50 (2011)