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Journal of Atomic, Molecular, and Optical Physics
Volume 2011 (2011), Article ID 637593, 6 pages
http://dx.doi.org/10.1155/2011/637593
Research Article

Ultrafast Dynamics of 1,3-Cyclohexadiene in Highly Excited States

1Department of Chemistry, Brown University, Providence, RI 02912, USA
2LCLS Laser Department, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
3Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA

Received 2 March 2011; Revised 11 May 2011; Accepted 15 June 2011

Academic Editor: Geraldo M. Sigaud

Copyright © 2011 Christine C. Bühler et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The ultrafast dynamics of 1,3-cyclohexadiene has been investigated via structurally sensitive Rydberg electron binding energies and shown to differ upon excitation to the 1B state and the 3p Rydberg state. Excitation of the molecule with 4.63 eV photons into the ultrashort-lived 1B state yields the well-known ring opening to 1,3,5-hexatriene, while a 5.99 eV photon lifts the molecule directly into the 3p-Rydberg state. Excitation to 3p does not induce ring opening. In both experiments, time-dependent shifts of the Rydberg electron binding energy reflect the structural dynamics of the molecular core. Structural distortions associated with 3p-excitation cause a dynamical shift in the p 𝑥 - and p 𝑦 -binding energies by 10 and 26 meV/ps, respectively, whereas after excitation into 1B, more severe structural transformations along the ring-opening coordinate produce shifts at a rate of 40 to 60 meV/ps. The experiment validates photoionization-photoelectron spectroscopy via Rydberg states as a powerful technique to observe structural dynamics of polyatomic molecules.