Fourier-transform infrared spectroscopy has been employed to study the adsorption, thermal transformation, and photoreactions of CH2I2 on powdered TiO2. At 35 °C, CH2I2 is adsorbed molecularly or dissociatively to form a surface species with CHx and C-O functional groups possibly derived from C-I bond scission of CH2I2. As the surface temperature is raised above 100°C, the adsorbed CH2I2 is transformed into CH3O(a) and HCOO(a) simultaneously, very likely via disproportionation of the reaction intermediate of dioxymethylene (-OCH2O-). Under UV irradiation in the presence of O2, adsorbed CH2I2 on TiO2 decomposes to form CO(a), HCOO(a), H2O(a), and CO2(g). But the CH2I2 photoreaction is almost terminated in the absence of O2. The possible initiation species involved in the CH2I2 photodecomposition is discussed.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry