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

J.J. NAJERA; R. WAMSLEY; D.J. LAST; K.E. LEATHER; C.J. PERCIVAL; A.B. HORN

INTERNATIONAL JOURNAL OF CHEMICAL KINETICS

JOHN WILEY & SONS INC

Lugar: New York; Año: 2011 vol. 43 p. 694 - 707

0538-8066

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-μmfilm 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 KO3 = (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