ICARUS Chamber Experiment: 2014 FIXCIT Study_20140106_Isoprene/Ozone/Water_Hydroxyl radical_No Seed_Isoprene + OH + O3, low NO, dry, no seeds

Goals:; Explore OH yield, product formation (carbonyls, peroxides, organic acids, and others), and Ozone-related GTHOS interference. ; Investigate any instrumental interferences of high ozone levels.

Summary:; Experiment went well, lots of products were made, both by OH and O3 + isoprene chemistry. A significant amount of the isoprene mass was converted to hydroxymethylhydroperoxide (HMHP) at this RH, as expected based on previous CIT measurements. Experiment time was shorter than hoped, due to bag volume depleting too quickly. LIF OHR instrument was taken off bag at 1.5 hour mark to conserve bag volume. The "end" of the experiment was when CF3O- CIMS saw that product formation stabilized and when PTRMS and GC-FID saw that isoprene was all gone - this happened at approximately 16:15. At reaction end (although it's technically still going in the bag), we did a test for some instruments to see if sampling directly from a port into the chamber gives the same answer as from a common sampling line. For I/A CIMS, CF3O- CIMS, and PTRMS, there does not appear to be significant differences. For O3/NOx, there appears to be a difference in the beginning of sampling, and these instruments now will be on their own line when O3 measurements are more critical. AMS reports losing ~30% of particle mass through a longer inlet. GC-FID tested out trapping methods, with limited success but will continue to work on it. The flow rate through LIF OHR was higher than expected, but this will be worked on tomorrow when this instrument will be off. At the end of the experiment, UV lights were also turned on at 100% for ~40 minutes. Photolysis of some species seen by CF3O- CIMS was observed. CRM OHR was not on the bag today, but at the end of the day reported success in measuring OHR of pyrrole and expects to be on tomorrow. Preparations for upcoming experiment, starting this evening, started approximately 19:00.

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

Experiment Category: Gas phase chemical reaction; Oxidant: Hydroxyl radical; Reactants: Isoprene, Ozone, Water; Reaction Type: Photooxidation; Relative Humidity: 5; Temperature: 25; Seed Name: No Seed; Pressure: 750 Torr