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International Journal of Photoenergy
Volume 2014, Article ID 850641, 10 pages
Research Article

Effect of Initial Orientation on the Laser-Induced Cycloaddition Reaction of Benzene and Ethylene

1School of Bioinformation, Chongqing University of Posts and Telecommunications, Chongqing 400065, China
2Department of Physical Sciences, Nicholls State University, P.O. Box 2022, Thibodaux, LA 70310, USA

Received 7 May 2014; Accepted 18 July 2014; Published 3 November 2014

Academic Editor: Fuli Li

Copyright © 2014 Shuai Yuan 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.


The [2 + 2] photocycloaddition reaction of benzene and ethylene was investigated by semiclassical dynamics simulation and complete active space self-consistent field (CASSCF) ab initio calculations. Following laser excitation of the benzene molecule, two mechanisms were observed depending on the location of the second C of ethylene in relation to the hexagonal prism space defined by the first C and the plane of the benzene ring. Synchronous formation of two bonds was observed when the second C is outside the prism space; an asynchronous mechanism is observed otherwise. Charge transfer was observed only in the asynchronous mechanism; CASSCF calculations suggest that the asynchronous mechanism involves a barrierless path from the Frank-Condon point to a conical intersection, while the synchronous mechanism involves 0.8 eV barrier. These results are consistent with a higher quantum yield observed in the simulations for the asynchronous pathway.