State-resolved reactive scattering by slice imaging: a new view of the Cl+C2H6 reaction.

We present state-resolved crossed beam scattering results for the reaction Cl+C2H6-->HCl+C2H5, obtained using direct current slice imaging. The HCl (v=0,J=2) image, recorded at a collision energy of 6.7+/-0.6 kcalmol, shows strongly coupled angular and translational energy distributions revealing features of the reaction not seen in previous studies. The overall distribution is mainly forward 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 at 8.0 kcalmol, but extends to much lower energy, implying substantial internal excitation in the ethyl radical coproduct. These results provide new insight into the reaction, and they are considered in terms of alternative models of the dynamics. 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.