Photolysis of ketene. I

Ketene has been photolyzed at 3660 and 3130 A both alone and in the presence of the inert gases C4F8 and SF6. The quantum yield of carbon monoxide has been determined at both wavelengths as a function of pressure and temperature. At 3660 A the quantum yield decreases with increasing pressure but increases with increasing temperature. At 3130 A the quantum yield with ketene alone remains 2.0 at both 37 and 100 °C at pressures up to 250 mm. At higher pressures of ketene or with added inert gas the quantum yield decreases with increasing pressure. The results are interpreted in terms of a mechanism in which intersystem crossing from the excited singlet state to the triplet state occurs at both wavelengths, and collisional deactivation of the excited singlet state by ketene is single stage at 3660 A but multistage at 3130 A.