Experiment: 2014 FIXCIT Study_20140121_ISOPRENE/hydrogen peroxide_Hydroxyl radical_No Seed_Isoprene + OH, low NO, dry, no seeds, lower initial concentration


Name: 2014 FIXCIT Study_20140121_ISOPRENE/hydrogen peroxide_Hydroxyl radical_No Seed_Isoprene + OH, low NO, dry, no seeds, lower initial concentration
Date: 2014-01-21

2014 FIXCIT Study

Seinfeld chambers

Experiment Set
FIXCIT experiments

Study isoprene low NO chemistry. The experiment will be similar to the experiment run on 01/02/2014, but the loading will be lower, so as to limit RO2 + RO2 chemistry.

We injected isoprene initially and like the experiment run on 01/19/2014 there was ISOPOOH contamination during the injection. We decided given the goals of the experiment to flush the bag for several hours to remove the ISOPOOH. After several hours of flushing the ISOPOOH was roughly around 200 ppt (see the worked up data for a more precise number). The source of contamination was found, and everything was cleaned again. No ISOPOOH was injected during the second injection of isoprene. Because we started the experiment later (i.e., after rush hour), the NO background was a lot lower than previous experiments (~10 ppt in the beginning). The lower isoprene loading in this experiment allowed for the HO2 pathway to dominate over the RO2 pathway and allowed for later generation products to form. During the experiment we saw ISOPOOH form and decay away. Unexpectedly IEPOX also formed and decayed away. There seemed to be a lower than expected amount of IEPOX formed. Perhaps wall loss was greater in this experiment than on 01/02/2014. For the PTR-MS and GC-FID, we trapped ISOPOOH/IEPOX at -40 deg C, so that yields of MVK and MACR for the experiment could be determined without the ISOPOOH/IEPOX interference.

Additional Notes
all instruments running

Experiment Details


  • Gas phase chemical reaction
Temperature: 27
Relative Humidity: 5
Seeded Experiment: No
Fuchs Adjusted Surface Area:
Condensation sink rate coefficient: 5
Reaction type:
Oxidant Name: Hydroxyl radical
Initial Oxidant Concentration Value: 2.0e6 (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
22 Parts Per Billion
hydrogen peroxide (784) 2 Parts Per Million

20140121_expTimeline.csv Timeline

UTC_hr Action
16:20 Capped near bag.
16:44 Isoprene injection started (~20 ppb).
16:52 Started filling near bag.
16:54 Isoprene injection stopped.
17:01 Bag completely full.
17:01 All instruments began sampling. Realized bag was contaminated with ISOPOOH
17:30 Start flushing bag.
21:30 Capped near bag.
21:41 Inject isoprene (~20 ppb)
21:51 Stop isoprene injection and fill bag.
21:54 Bag full.
22:00 All instruments start sampling.
22:30 All instruments stop sampling.
22:34 Inject H2O2 (~2 ppm).
23:52 Stop H2O2 injection.
23:53 Add pulses of injection air into the bag to facilitate mixing.
23:55 Cap bag.
00:00 All instruments start sampling the bag.
00:30 Turn on 100% lights.
05:30 Turn off lights.
06:00 All instruments stop sampling.

Light Flux Characterizations:
2013-12-16 (#17)
Particle Loss Characterizations:
2013-03-07 (#13)
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: