Hist Direct Detection of HONO in the Reaction of Methylnhrite (CH_3ONO) with OH Radicals

摘要

We report on the development of a new environmental simulation chamber coupled with an in situ continuous wave cavity ring-down spectrometer operating in the near IR (~1.5 μm). The first application reported in this paper dealt with the chemical mechanism of UV photolysis of methyl nitrite (CH_3ONO) in air. HONO has been detected for the first time and shown to be formed in the OH + CH_3ONO reaction. A dense spectrum of cis-HONO absorption lines has been observed near 1.5 ?m, in agreement with a previous study (Guilmot et al). CH_2O has been measured as primary product with good sensitivity and time resolution. In contrast to Zhao et al., we did not detect any NO_2 absorption features in this wavelength range. Calibration experiments provided very low NO_2 absorption cross sections in this region (~10~(-25) cm~2), leading to conclude that NO_2 cannot be observed in this wavelength range in the presence of equal amounts of CH_2O.