Photodissociation and photodetachment of molecular negative ions. VII. Ions formed in CO2/O2/H2O mixtures, 3500ndash;5300 Aring;

摘要

Photodestruction cross sections have been measured for CO3−, CO3−⋅H2O, CO4−, CO4−⋅H2O, HCO3−, and HCO3−⋅H2O at various ion laser and dye laser wavelengths between 5300 and 3500 A˚ using a drift tube mass spectrometer as the source of the ions. CO3−shows a structureless peak centered about 4500 A˚, which is attributed to photodissociation. The possible excitation of CO3−in these studies was investigated in detail and no evidence was found for any excitation. Additional evidence is presented which indicates that the bond energyD(CO2–O−) is less than or equal to 1.9 eV. The CO3−⋅H2O cross section decreases smoothly with decreasing wavelength over this wavelength range. CO4−photodestruction was observed at 3500 A˚, but the other ions listed above have cross sections below 10−19cm2, and possibly zero, throughout this spectral region.