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, Cl 2 , and small quantities of H 2 . Acetylene is also produced. While it is possible that the C 2 H 2 arises, in part, from the decomposition of vibrationally excited ground states of C 2 H 3 Cl and/or C 2 H 4 , 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 ClCl interaction predicted for a «Rydberg «state of 1,1‐C 2 H 4 Cl 2 . Varying small yields of CH 4 are observed in the presence and absence of NO. The effect of large pressures of CF 4 on the quantum yields of the major products is extremely small. The extinction coefficient for 1,1‐C 2 H 4 Cl 2 at 147 nm and 296°K is 246 ± 29 cm −1 ± atm −1 .