Spectroscopic characterization of isomerization transition states
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Baraban_SpecChar.pdf
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Author(s)
Mellau, Georg Ch.
Stanton, John F.
Merer, Anthony J.
Baraban, Joshua Herschel
Changala, P. Bryan
Field, Robert W
Date Issued
December 2015
Journal
Science
Publisher
American Association for the Advancement of Science (AAAS)
Citation
Baraban, Joshua H., P. Bryan Changala, Georg Ch. Mellau, John F. Stanton, Anthony J. Merer and Robert W. Field. “Spectroscopic Characterization of Isomerization Transition States.” Science 350, no. 6266 (December 10, 2015): 1338–1342.
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Author's final manuscript
Abstract
Transition state theory is central to our understanding of chemical reaction dynamics. We demonstrate a method for extracting transition state energies and properties from a characteristic pattern found in frequency-domain spectra of isomerizing systems. This pattern—a dip in the spacings of certain barrier-proximal vibrational levels—can be understood using the concept of effective frequency, ω[superscript]eff. The method is applied to the cis-trans conformational change in the S[subscript 1] state of C[subscript 2]H[Subscript 2] and the bond-breaking HCN-HNC isomerization. In both cases, the barrier heights derived from spectroscopic data agree extremely well with previous ab initio calculations. We also show that it is possible to distinguish between vibrational modes that are actively involved in the isomerization process and those that are passive bystanders.
MIT Department
Massachusetts Institute of Technology. Department of Chemistry
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DOI of Published Version
https://doi.org/10.1126/science.aac9668
