Hydrolysis of Organic Nitrates
Principal Investigators: John Shilling
Participants: Naruki Hiranuma and Chen Song
Collaborators: Lynn Russell and Shang Liu of the University of California, San Diego; Mikhail Pekour; and Dan Cziczo.
FTIR analysis of the chemical composition of SOA particles generated from the photooxidation of trimethyl benzene as a function of relative humidity. The data show organic nitrate species are hydrolyzed to alcohols as relative humidity increases, likely in the particle phase. Carbonyl groups may also be replaced by carboxylic acid, likely as a result of differences in gas-phase chemistry. Enlarge Image
In collaboration with Prof. Lynn Russell, a graduate student visiting from the University of California, San Diego, PNNL conducted chamber experiments investigating organonitrate hydrolysis. In these experiments, organic aerosol was produced from the photooxidation of trimethyl benzene at variable relative humidity. We found that organic nitrates are formed with a particle phase yield of ~20%, but hydrolyze to form alcohols as relative humidity increases (see Figure). Concurrent with the hydrolysis of the organic nitrate functional groups, we observed a marked decrease in the absorption of blue visible light by the particles. These experiments show that: 1) organic nitrates may be an important component of freshly produced particles, 2) particulate organic nitrates would be converted to alcohols on timescales of several hours under typical atmospheric conditions, and 3) the radiative properties of aerosol particles may be affected by the chemical composition of the particles.