| A bench-scale matrix isolation system coupled with an FTIR spectrometer has been established for investigating the formation mechanism of tropospheric ozone. A mixture of NO2, O2, VOC (Ethylene) and Ar is deposited on the matrix chamber at 8–10 K under vacuum (10−3 Pa absolute). The matrix is then photolyzed to verify the mechanism of tropospheric ozone formation. Results show that both O3 and NO are produced during the photolysis experiments, which serves as the verification of the reaction pathway using matrix isolation technique. The reaction mechanism identifies the formation of O• radical generated from the photolysis of NO2, capable of reacting with ethylene and O 2 to form aldehyde/ketene (contain CO•) and O 3, although at low temperature (8–10 K) O3 is the major product. Ar matrix prevents the mobility of CO• at low temperature (8–10 K), however after warming the matrix (25–30 K), the less rigid matrix initiates reaction between different species (H •, CH2••) with CO • to generate fomaldehyde and ketene. The amount of production during both simultaneous and sequential methods has been compared, which reveals that reactions predominantly occur on the surface of the matrix using simultaneous method, and on the solid matrix surface and in the gaseous phase before deposition in the simultaneous method. It is recommended that Gaussian molecular simulation software can be used to identify unknown species generated during photolysis. |
