Experiment: 2014 FIXCIT Study_20140123_ISOPRENE/OZONE_Hydroxyl radical_No Seed_Isoprene + OH + O3, low NO, 50% humidity, no seeds


Name: 2014 FIXCIT Study_20140123_ISOPRENE/OZONE_Hydroxyl radical_No Seed_Isoprene + OH + O3, low NO, 50% humidity, no seeds
Date: 2014-01-23

2014 FIXCIT Study

Seinfeld chambers

Experiment Set
FIXCIT experiments

This experiment is designed to be easily compared to our dry no-scavenger isoprene ozonolysis experiment (on January 6th), with the only change in conditions being the humidity (50% RH instead of 3-4%). Our main goal is to see how the products of humid ozonolysis compare with those of dry ozonolysis. The hot, wet conditions at the end may also help with ongoing investigation of GTHOS interference.

The experiment went as planned; initial conditions all matched the values we were aiming for, with 601 ppbv of ozone, 53% RH, and approximately 100 ppbv of isoprene at 25 degrees C. Ozonolysis proceeded rapidly, with the CF3O- CIMS observing the usual ozonolysis products (e.g. HMHP), and as we did not use an OH scavenger, the CIMS saw evidence of ISOPOOH and IEPOX formation as well. At the end, the temperature was ramped to 45C, during which a number of ozonolysis product signals increased and GTHOS was able to observe the temperature-dependence of interferences.

Additional Notes
all instruments sampling

Experiment Details


  • Gas phase chemical reaction
Temperature: 25
Relative Humidity: 50
Seeded Experiment: No
Fuchs Adjusted Surface Area:
Condensation sink rate coefficient: 50
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
  • Alkene
90 Parts Per Billion
OZONE (24823) 600 Parts Per Billion

20140123_expTimeline.csv Timeline

UTC_hr Action
15:05 T/RH/NOx/O3 sampling; bag cooled to 25C.
15:30 Began humidification.
17:06 Stopped humidifying; continued filling bag with dry air.
17:49 Stopped filling bag.
17:56 Started O3 injection.
19:30 Started adding air to refill and dilute bag.
19:38 Stopped O3 injection.
19:42 Stopped dry air injection.
20:00 Injected 10.25 uL isoprene.
20:19 Stopped injection.
25:00 Set temperature to ramp to 45C.
25:40 Temperature stabilized in the chamber (still appeared to be ramping in bag).
26:10 Temperature fully stabilized in bag.
26:25 Bag cooling and flushing.

Light Flux Characterizations:
2013-12-16 (#17)
Particle Loss Characterizations:
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: