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

Abstract

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 λ=312 nm. HCCO was generated in the reaction system in the reactions NO₂+hν→O(³P)+NO, O(³P)+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/k₁=(0.28±0.10) and k_1d/k₁=(0.64±0.12). Formation of HNCO could not be confirmed. Other species detected include H₂O and HONO. These are formed, together with additional CO, in consecutive reactions of H atoms and OH radicals.