Laboratory studies of products of N₂O₅ uptake on Cl⁻ containing substrates

Abstract

The reaction of dinitrogen pentoxide with chloride‐containing substrates over a concentration range relevant to the atmosphere was examined using cavity ring‐down spectroscopy (CaRDS) and chemical ionization mass spectrometry (CIMS). The main product, nitryl chloride (ClNO 2 ), was formed in efficiencies in the range 0.2 to 0.8 for chloride concentrations of 0.02 to 0.5M. These values are somewhat lower than those from previous, less detailed, measurements carried out mainly at much larger chloride concentrations in NaCl‐water mixtures. Substrates having pH<2 also evolved molecular chlorine (Cl 2 ), with ClNO 2 as an intermediate. The ClNO 2 yields are compared to recent field measurements of N 2 O 5 and ClNO 2 as a function of aerosol chloride concentration and shown to quantitatively explain the observations.