Heterogeneous oxidation reaction of gas‐phase ozone with anthracene in thin films and on aerosols by infrared spectroscopic methods

In this paper, a real‐time laboratory study of the heterogeneous oxidation reaction of gas‐phase ozone with anthracene on surface substrates by using infrared spectroscopy in two distinctly different experimental configurations is reported. One set of kinetic measurements was made by attenuated total internal reflection infrared (ATR‐IR) spectroscopy using approximately 75‐nm films of anthracene adsorbed on ZnSe, for which the reactive uptake coefficient was determined to be (2.0 ± 1.1) × 10^?7. Using an aerosol flow tube coupled to an infrared spectrometer (AFT‐IR), similar measurements were made on (NH₄)₂SO₄ (ammonium sulfate) aerosols coated with a 0.1‐μm film of anthracene. The aerosol kinetic results as a function of the ozone concentration are consistent with a Langmuir–Hinshelwood‐type mechanism, for which the ozone‐partitioning coefficient was K = (1.4 ± 1.7) × 10^?16 cm³ molecule^?1, and the maximum pseudo‐first‐order rate coefficient was k^I_max = (0.035 ± 0.016) s^?1. Infrared spectroscopic and mass spectrometric analysis of the ozonolysis reaction in the bulk phase identified the main ozonolysis products as dihydroxyanthrones, 9,10‐endoperoxide–anthracene, 9,10‐anthraquinone, and anthrone. Larger products were also seen in the mass spectra, most likely the result of secondary product and oligomer formation. © 2011 Wiley Periodicals, Inc. Int J Chem Kinet 43: 694–707, 2011