Photooxidation of Formaldehyde in Solid Oxygen and Argon/Oxygen Matrices at 12 K

Article abstract of DOI:10.1021/j100220a011

Matrix-isolated formaldehyde in solid O2, Ar/O2, and Ar matrices at 12 K has been photolyzed by ultraviolet light in the 220 - 400 nm range.The photoproducts were identified by infrared spectroscopy.Stable oxidation products were CO, CO2, H2O, H2O2, O3, and HCOOH, whereas relatively unstable products were HO2, its hydrogen-bonded dimer (HO2)2, formylperoxy radical HC(O)OO, and performic acid.The observed photoproduct distribution is rationalized by the stoichiometry of chemical reactions involving one C atom, two H atoms, and odd numbers of O atoms in the cage.Photolysis of the Ar/O2/H2CO sample (10 percent O2 in solid Ar) gave poor yields of radical species.Under the experimental conditions employed, the photochemical oxidation process is not driven to completion, and therefore it is possible to trap reactive intermediates for spectroscopic and kinetic studies.Photodissociation threshold of H2CO and (H2CO)2 in solid Ar have been measured with tunable, pulsed UV laser photolysis to show that (H2CO)2 has a lower treshold than H2CO.