Goals:
Explore the gas-phase chemistry of pinonaldehyde when HO2, NO, and NO2 are all present.

Summary:
Synthesized pinonaldehyde was added through a heated line for a few hours to get enough into the bag. This was the first time we had injected pinonaldehyde and learned that next time, we shouldn't heat the injection line or the bulb because that facilitates the oxidation of pinonaldehyde to pinonic acid. Thus both were injected at initial mixing ratios of ~15 ppb (with a fair amount of uncertainty) to ~10 to 20 ppb pinonic acid (also with uncertainty). The pinonic acid is expected to react with OH about 4 times slower than pinonaldehyde, although there is a channel for the production of pinonic acid from the pinonaldehyde photooxidation as well. After initiating OH oxidation by methyl nitrite photolysis, CF3O- CIMS observed that almost all of the carbon ended up as the PAN of pinonaldehyde (which Geoff calls "PiPAN"). Perhaps due to the high formation of the PiPAN, we observed high amounts of nucleated organic aerosol (~40 ug/m^3 at the end of the experiment). At the end of the experiment, most of the pinonaldehyde was gone, but more than half of the pinonic acid was left (perhaps because it's produced as well as lost through OH oxidation). We injected methyl nitrite twice, to replenish the OH. At the end, lights were turned off and the bag was flushed within 20 minutes.

Organization: 2014 FIXCIT Study
Lab Affiliation: California Institute of Technology
Chamber: Seinfeld chambers

Experiment Category: Gas phase chemical reaction
Oxidant: Hydroxyl radical
Reactants: PINONALDEHYDE, Pinonic acid, Methyl nitrite
Reaction Type: Photooxidation
Relative Humidity: 5
Temperature: 26
Pressure: 750 Torr