The kinetics and mechanism of the formation of chlorine monofluoride in the photochemical reaction between chlorine and fluorine at 365 nm

Abstract The formation of ClF in the photochemical reaction between Cl 2 and F 2 at 365 nm has been investigated at temperatures between 30 and 50 °C. The reaction is a chain of short length. In the presence of less than 40 Torr of ClF, ClF is the only final product. The quantum efficiency Φ ClF of its formation is directly proportional to the F 2 pressure. At ClF pressures above approximately 15 Torr, Φ ClF is independent of the light intensity whereas the ClF pressure has a strong decreasing effect. At ClF pressures above 40 Torr the simultaneous formation of ClF 3 becomes observable. The experimental results can be explained by the following mechanism: The efficiency factor of ClF as the third body in reaction (5) is about 35 times larger than those of the other gases present, indicating that chemical forces are involved in its action. A value of 2.5 × 10 3 M −3 s −1 was obtained for the rate constant k 2 of reaction (2) at 30 °C.