Matrix isolation study of interaction between chlorine, ozone and nitrogen oxides

The motivation for this work is the recognition that the photochemical oxidant cycle of ozone formation can be altered through the uptake of atomic chlorine in the NO_x-VOC-O₂ system. As a result, the formation rate and mechanistic pathway of tropospheric ozone may be altered. This study evaluates the role of reactive chlorine on ozone formation rate and mechanism. Matrix Isolation coupled with Fourier Transform Infrared Spectroscopy is employed to quantify the reactions taking place on matrix surface. The impact of these reactions in ozone formation is assessed. Based on the results it was found that the reactions in the matrix occur mainly on the surface. Important intermediates and products such as ClO, ClOO, ClNO₂ and ClONO₂ have been identified. Gaussian molecular simulation software has been used to verify the results for the intermediates and products identified. B3LYP was used as the approximation method and 631G(d) was used as the basis set for Gaussian calculations. It is expected that the results from this study will provide new insights into the role of chlorine in the tropospheric reactions. Many unknown peaks have also been seen in the experimental results. Identification of these unknown peaks is important in establishing a definite reaction pathway. This can be done using IRC calculations in Gaussian simulation.