FTIR study of the products of the reaction between HCCO and NO

The main pathways of the reaction HCCO + NO --> products (1) were investigated at room temperature in the gas phase in Ar at 570 mbar pressure by employing FTIR spectroscopy. Mixtures of NO2-C2H2-NO-Ar were photolysed under stationary conditions using a high-pressure Hg lamp at lambda = 312 nm. HCCO was generated in the reaction system in the reactions NO2 + h nu --> O(P-3) + NO, O(P-3) + C2H2 --> H + HCCO. The main products of reaction (1) include CO2, CO, and HCNO. The results can be rationalised with the reaction channels HCCO + NO --> HCN + CO2 (1a) and HCCO + NO --> HCNO + CO (1d). The branching ratios were determined to be k(1a)/k(1) = (0.28 +/- 0.10) and k(1d)/k(1) = (0.64 +/- 0.12). Formation of HNCO could not be confirmed. Other species detected include H2O and MONO. These are formed, together with additional CO, in consecutive reactions of H atoms and OH radicals.