Rotationally-resolved reactive scattering: imaging detailed Cl + C2H6 reaction dynamics

PHYS 407

Cunshun Huang, cunshun@chem.wayne.edu1, Wen Li, wenli2@ic.sunysb.edu2, and Arthur G. Suits, asuits@chem.wayne.edu1. (1) Department of Chemistry, Wayne State University, Detroit, MI 48202, (2) Department of Chemistry, Stony Brook University, Stony Brook, NY 11794
The rotationally-resolved reactive scattering results for the reaction of Cl (2P3/2) with ethane has been studied using the crossed molecular beam technique with DC slice imaging at collision energies from 3.2 to 10.4 kcal/mol. The products HCl (v, J) (v = 0, J = 0-5) were state-selectively ionized using 2+1 Resonance Enhanced Multiphoton Ionization. The images were used to obtain the center-of-mass frame product angular distributions and translational energy release distributions. The results show strongly coupled angular and translational energy distributions revealing features of the reaction not seen in previous studies. Two general features were found in all probed HCl quantum states at 6.7 kcal/mol collision energy, and these features have distinct translational energy release and angular distributions. The overall distribution is mainly forward-sideways scattered with respect to the Cl beam, with a translational energy distribution peaking near the collision energy. However, there is a substantial backscattered contribution that is very different. It shows a sharp peak near the energetic limit, but extending to much lower energy, implying substantial internal excitation in the ethyl radical co-product. The results for HCl (v = 0, J = 2) at four collision energies were also compared to investigate the energy-dependent dynamics. We discuss the reaction in terms of a variety of models of polyatomic reaction dynamics. The dynamics of this well studied system are more complicated than can be accounted for by a single mechanism and the results call for further theoretical and experimental investigations. This work represents the first genuine crossed-beam study in which a product other than the methyl radical was detected with quantum state specificity, showing the promise of the approach generally for high resolution state-resolved reactive scattering.

Poster Session
7:30 PM-10:00 PM, Wednesday, 13 September 2006 Moscone Center -- Hall D, Poster

8:00 PM-10:00 PM, Monday, 11 September 2006 Moscone Center -- Hall D, Sci-Mix

Division of Physical Chemistry

The 232nd ACS National Meeting, San Francisco, CA, September 10-14, 2006