Laboratory studies on the production of alpha-pinene-derived organic nitrates and their atmospheric fate
Currently, the formation yields of organic nitrates from the oxidation of biogenic volatile organic compounds, such as α-pinene, is highly uncertain, negatively impacting our knowledge on tropospheric ozone production and the fate of atmospheric NOx. To lower this uncertainty, we quantified the organic nitrate yield from the OH radical oxidation of α-pinene under high NOx conditions. The α-pinene- derived nitrates created in chamber experiments readily partitioned to the aerosol phase and underwent particle phase hydrolysis, indicating that these processes are likely a sink for atmospheric NOx. The hydrolysis of organic nitrates was found to be specific acid-catalyzed and proceeded via unimolecular mechanisms under acidic conditions. The hydrolysis lifetime of a synthesized α-pinene nitrate standard was well within the lifetime of an atmospheric particle. Previously unreported α-pinene oxidation products from chamber studies were identified using mass spectrometry, and, for the first time, individual α-pinene-derived nitrates were identified in a complex mixture. In addition, paper spray ionization was adapted for the direct detection of organosulfates from filter samples and a Raman technique was developed to directly measure the pH of single aerosol particles, for the first time.
Shepson, Purdue University.
Atmospheric Chemistry|Analytical chemistry
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