CHEMICAL-DYNAMICS OF THE REACTION BETWEEN CHLORINE ATOMS AND DEUTERATED CYCLOHEXANE

The dynamics of the reaction Cl + cyclobexane-d12 (c-C6D12) --> DCl + C6D11 have been investigated by using time-resolved diode laser absorption spectroscopy to probe the reaction product DCl. The chlorine atoms have been generated by the UV photolysis of S2Cl2 and NOCl. Nascent DCl produced in the reaction is rotationally cold (below room temperature) and translationally hot. As the collision energy increases, the DCl product translational energy increases dramatically, the rotational energy increases slightly, and the vibrational energy remains essentially the same. Most of the initial translational collision energy appears as translational energy of the reaction products, and this observation can be simply explained as being a result of the heavy-light-heavy atom reaction kinematics. An extremely simple ''spectator'' model, where C6D11 is the spectator, fits this experimental result very well. The cold DCl rotational state distribution may be an indication that Cl atoms abstract D atoms with a collinear C--D--Cl recoil geometry. Quasi-classical trajectory calculations using an empirical three-body model LEPS surface (C6D11 is considered as a structureless particle) successfully predict a number of the experimental results.