Primary processes in the 147-nm photolysis of 1,1-dichloroethane

The room temperature photolysis of 1,1-dichloroethane at 147 nm in the pressure range of 1.34-196.2 torr is characterized almost entirely by the molecular elimination of HCl, Cl₂, and small quantities of H₂. Acetylene is also produced. While it is possible that the C₂H₂ arises, in part, from the decomposition of vibrationally excited ground states of C₂H₃Cl and/or C₂H₄, in this particlar case serious consideration has to be given to alternative explanations where the products of the primary processes are formed in electronically excited states. The ±, elimination of molecular chlorine is not inconsistent with an increased degree of Cl? Cl interaction predicted for a «Rydberg «state of 1,1-C₂H₄Cl₂. Varying small yields of CH₄ are observed in the presence and absence of NO. The effect of large pressures of CF₄ on the quantum yields of the major products is extremely small. The extinction coefficient for 1,1-C₂H₄Cl₂ at 147 nm and 296°K is 246 ± 29 cm^?1 ± atm^?1.