Spectroscopic characterization of isomerization transition states

Joshua H. Baraban, P. Bryan Changala, Georg Ch Mellau, John F. Stanton, Anthony J. Merer, Robert W. Field

Research output: Contribution to journalArticlepeer-review

45 Scopus citations


Transition state theory is central to our understanding of chemical reaction dynamics.We demonstrate amethod for extracting transition state energies and properties froma 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, ωeff.The method is applied to the cis-trans conformational change in the S1 state of C2H2 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.

Original languageEnglish
Pages (from-to)1338-1342
Number of pages5
Issue number6266
StatePublished - 11 Dec 2015
Externally publishedYes

ASJC Scopus subject areas

  • General


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