H. SU, T XIANG, K LIU, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080, China.
Time-Resolved Fourier Transform Infrared (TR-FTIR) emission spectroscopy has been used extensively to study the dynamics of gas-phase free radical reactions. Radicals of CH2Br are believed to be important reactive intermediates involved in atmospheric pollution chemistry. It is expected that this highly reactive and exothermic reaction of CH2Br with NO2 has multiple reaction channels and interesting chemical transformations. However, except a few kinetics measurements, it has been lack of the knowledge of its reaction products, channels, dynamics and mechanisms up to now. In this work, we have employed step-scan TR-FTIR emission spectroscopy to investigate these aspects of the CH2Br + NO2 reaction. By probing the infrared fluorescence emitted from vibrationally excited molecules in real time, the elementary reaction products and their vibrational state distribution can be identified from TR-FTIR emission spectroscopy, revealing the information of the product channels and reaction dynamics. Here, we have observed multiple elementary reaction products of H2CO, HBr, CO2, CO, NO from the CH2Br + NO2 reaction, identified the corresponding reaction channels and analyzed the product vibrational state distributions. The reaction mechanism and dynamics is elucidated from these experimental results combined with B3LYP/6-311G(d,p) level of DFT calculations on the reaction energetics.