Experiment: 2014 FIXCIT Study_20140119_/ISOPRENE/4-hydroxy-3-hydroperoxy ISOPOOH/hydrogen peroxide_Hydroxyl radical_Ammonium sulfate_Isoprene and 4,3-ISOPOOH + OH, low NO, 50% humidity, (NH4)2SO4 seeds


Name: 2014 FIXCIT Study_20140119_/ISOPRENE/4-hydroxy-3-hydroperoxy ISOPOOH/hydrogen peroxide_Hydroxyl radical_Ammonium sulfate_Isoprene and 4,3-ISOPOOH + OH, low NO, 50% humidity, (NH4)2SO4 seeds
Date: 2014-01-19

2014 FIXCIT Study

Seinfeld chambers

Experiment Set
FIXCIT experiments

Investigate the gas and particle phase composition of the isoprene low NO oxidation mixture, in the presence of moderate relative humidity and wet ammonium sulfate seeds. Test out ozone addition to GTHOS inlet.

This was an interesting experiment. We meant to inject only isoprene, but 4,3-ISOPOOH was also injected due to unexpected contamination of the "hydrocarbon injection" line from Friday's experiment. So there was ~ 60 ppb isoprene, and ~ 10-30 ppb ISOPOOH in the bag. The RH was 50.5% and the particle sulfate mass concentration was ~ 54 ug/m3 when the experiment started. The particles were injected deliquesced, so they should have water still on them in some form. Once the OH-oxidation started, a few things stood out as interesting. First, very little IEPOX was observed in the gas-phase despite plenty of isoprene and ISOPOOH around. In comparison, the low NO isoprene photooxidation produced an order of magnitude more IEPOX, relatively. The NO was low (~ 20 ppt throughout the experiment) so the RO2 radicals were not reacting with NO preferentially. During SOAS, gas-phase IEPOX was also low. Not much particle organic mass formed (~5 ug/m3 overall) and the organic fraction was seemingly oxidized away from the gas-phase OH, something that we have also noticed in the past. Second, ISOPOOH was lost faster than isoprene, which was not expected based on OH reaction alone, so heterogenous chemistry might be important for ISOPOOH as well in the presence of wet seed aerosol or wet walls. Lots of hydroxyacetone and glycolaldehyde were produced from the oxidation of isoprene low-NO products. Some mystery masses were observed by the PTRMS and I- CIMS, that were not seen in other isoprene low NO experiments (perhaps products of the aqueous chemistry.) GTHOS got a chance to try out ozone addition to the inlet, which did produce plenty of what appears to be interference, but post-processing is needed to gauge the success of this trial. At the end of the experiment, the temperature was ramped up to 45 deg C, held for 30 min, then ramped down again to room temperature. Changes in the AMS organic signal was observed.

Additional Notes
Instrument Status: TD LIF - up PTRMS - up GTHOS - up LIF OHR - up CRM OHR - up NO CL - up GLY LIP - down FOR LIF - down I/A CIMS - up NCIMS - up RHTO3 - up GC FID - up AMS - up TQC1 - up TQC2 - up TOFCIMS - up

Experiment Details


  • Gas phase chemical reaction
  • Aerosol formation
Temperature: 28
Relative Humidity: 51
Seeded Experiment: Yes
Type of Seed: Ammonium sulfate
Initial Seed Concentration Value: 54
Seed Concentration Units: micrograms_per_cubic_meter
Fuchs Adjusted Surface Area:
Condensation sink rate coefficient: 51
Reaction type:
Oxidant Name: Hydroxyl radical
Initial Oxidant Concentration Value: 1e6 (molecules_per_cubic_centimeter)
RO2 Main Fate: HO2
RO2 Lifetime: (Seconds)
Pressure: 750 Torr

Data Set plots
Choose a file: Choose the X-Axis:

Experiment Set Details

Name: FIXCIT experiments
Time format and units: Seconds past midnight
The Focused Isoprene eXperiment at the California Institute of Technology (FIXCIT) was a collaborative study at the atmospheric chambers of Caltech during January 2014. FIXCIT is the laboratory component of SOAS, and is aimed toward (1) better understanding the chemical details behind ambient observations relevant to the southeastern United States, (2) advancing the knowledge of atmospheric oxidation mechanisms of important biogenic hydrocarbons, and (3) characterizing the behavior of field instrumentation using authentic standards. A series of chamber experiments was conducted to investigate the oxidation of isoprene, α-pinene, methacrolein, pinonaldehyde, acylperoxy nitrates, isoprene hydroxy nitrates (ISOPN), isoprene hydroxy hydroperoxides (ISOPOOH), and isoprene epoxydiols (IEPOX). Pinonaldehyde and isomer-specific standards of ISOPN, ISOPOOH, and IEPOX were synthesized, enabling study of the oxidation mechanisms and instrument responses for these compounds.


  • Allen H. Goldstein UC Berkeley
  • William H. Brune Penn State University
  • Ronald C. Cohen UC Berkeley
  • Delphine K. Farmer Colorado State University
  • Manjula R. Canagaratna Aerodyne
  • Douglas R. Worsnop Aerodyne
  • Jose L. Jimenez University of Colorado Boulder
  • Frank N. Keutsch Harvard
  • Saewung Kim UC Irvine
  • Alex B. Guenther UC Irvine
  • John E. Mak SUNY Stonybrook
  • Geoffrey S. Tyndall NCAR
  • Denise D. Montzka NCAR
  • Andrew J. Weinheimer NCAR
  • Alam Hasson Fresno State


Principal investigators:

Paul O. Wennberg
Phone: 626 395 2447
E-mail: wennberg@caltech.edu
OrcID: 0000-0002-6126-3854

John H. Seinfeld
Phone: 626-395-4635
E-mail: seinfeld@caltech.edu
OrcID: 0000-0003-1344-4068

John D. Crounse
Phone: 626-395-8655
E-mail: crounjd@caltech.edu
OrcID: 0000-0001-5443-729X

Tran B Nguyen
Phone: 5307525987
E-mail: tbn@ucdavis.edu
OrcID: 0000-0001-9206-4359

Data Manager:

Tran B. Nguyen
Phone: 5307525987
E-mail: tbn@ucdavis.edu


Reactant Compound type Concentration Concentration units
Aerosol 54 Microgram Per Cubic Meter
  • Alkene
60 Parts Per Billion
4-hydroxy-3-hydroperoxy ISOPOOH
  • Alcohol
  • Alkene
  • Hydroperoxide
20 Parts Per Billion
hydrogen peroxide 1050 Parts Per Billion

20140119_expTimeline.csv Timeline

UTC_hr Action
14:30 GTHOS started sampling dry background
14:51 Started RH/T/NOx/O3 sampling
15:05 Started humidifying by flushing (43 psi @ source) 27.5 degC bath
15:30 GTHOS stopped sampling
16:00 Capped Near bag; filling bag with humid air only
16:27 Stopped injecting humid air; added dry air to fill bag
16:53 Stopped flow into bag; exhaust capped
18:03 Started injecting seed through wet wall denuder (heated 90degC) 0.06M ammonium sulfate
18:42 Stopped injecting seed; sulfate in bag ~ 100 ug/m3
18:50 GCFID started sampling
18:52 Refilling chamber with humid air
19:00 PTRMS started sampling
19:15 All other instruments started sampling bag
19:22 Injected 5 uL isoprene (~ 50 ppb)
19:40 Injected 1 uL isoprene (~ 10 ppb)
20:00 Stopped isoprene injection
20:08 Started H2O2 injection; bath 37 degC; 55 uL of 50% H2O2
21:04 Stopped H2O2 injection (trace leveled on CIMS)
21:15 100% UV lights on
26:35 Lights off
27:05 Temperature ramp up to 45 degC
27:30 Reached temperature; holding
28:07 Ramp down to 25 degC
28:15 Instruments stopped sampling
28:32 Start refilling then flushing bag

Light Flux Characterizations:
2013-12-16 (#17)
Particle Loss Characterizations:
2013-03-09 (#15)
Vapor Loss Characterizations:

Chamber Details

Name: Seinfeld chambers
Volume in cubic meters: 22
Shape: Rectangular Prism
Surface area in cubic meters: 48
Flow Mode: Batch
Flow through rate in liters per minute:
Body Material: Teflon
Body thickness: 2
Replacement date:
Replacement frequency: As needed
Cleaning method: Flushing with air Flushing with air with UV lights on Oxidation
o3 background: < 0.5 ppb
nox background: 40 ppt
Particle background in micrograms per cubic meter: < 0.01 ug/m3
Air filtration method: Custom filtration canisters to remove NOx, hydrocarbons, water, particles, ozone, SOx from pressurized ambient air.
Mixing method: 1
Mixing method material: Pulsed air jets, manually actuated
Temparature Control: Yes
Temparature measurements recorded: Yes
Temparature range (min degrees celcius): 10
Temparature range (max degrees celcius): 45
Humidity Control: Yes
Humidity Measurements Recorded: Yes
Relative humidity range (min percent): 4
Relative humidity range (max percent): 90
Particle experiment capability: 1
Lights: Yes
Light source type(s): UV black lamps (350 nm centered)
Supplemental information: https://www.worldscientific.com/doi/abs/10.1142/9789813147355_0001
Additional Notes: