Characterization of the nitrate pre-reactor for the generation of defined nitrate radical concentrations under various conditions

Overview

• Atmospheric simulation chambers are widely used to investigate the formation and evaluation of secondary organic aerosol (SOA).
• Biogenic and anthropogenic volatile organic compounds (VOCs) are emitted to the atmosphere and get oxidized through gas-phase chemical reactions to SOA precursor compounds that can condense on surfaces.
• The most abundant atmospheric oxidant is the OH radical, which is formed via photolytic processes.
• Due to its high reactivity, the OH concentrations decrease rapidly after sunset.
• As a result, ozone and nitrate radicals, which arise from the reaction from ozone with NO2, are the most important atmospheric oxidants during nighttime.
• Many studies focused on the OH oxidation of VOCs, but reactions with NO3 radicals remain understudied.
• To study these pathways without large contribution of ozonolysis, a pre-reactor is often used in chamber experiments, which allows the injection of nitrate radicals while controlling the injected ozone levels.
• In this work, the contribution of O3 NO2 NO3 radicals and N2O5 depending on reaction times, dilution and initial concentrations should be investigated.
• contact: Peter Mettke, mettke@tropos.de