Major products in the photochemistry of perylene adsorbed in models of atmospheric particulate matter

The photodegradation of adsorbed perylene is strongly influenced by the environment in which it is found as demonstrated by the nature of the photoproducts characterized on the adsorbed state in comparison to its photochemical behavior in solution. The separation, characterization, and identification of the products were carried out using HPLC equipped with UV–vis diode array and MS detection. Two of the products were identified as 1,12-perylenedione and 3,10-perylenedione. Three additional products were characterized as a perylenedione and two perylenediols based on their m/z ratio. Based on this information, two possible mechanisms of formation were proposed for the identified diones. The experimental data showed that both the radical cation and singlet oxygen participate in the route of photodegradation of perylene which occurs through a mixed Type I and Type II pathways. These results assist in the understanding of complex processes undergone by perylene and other PAHs in the environment.