Experiment: Caltech Atmospheric Chamber_20131118_ISOPRENE/CYCLOHEXANE_Ozone_No Seed_Dry


Name: Caltech Atmospheric Chamber_20131118_ISOPRENE/CYCLOHEXANE_Ozone_No Seed_Dry
Date: 2013-11-18

Caltech Atmospheric Chamber

Near/Far Bag 2012-2015 (Tran)

Experiment Set
Isoprene ozonolysis (various amounts of water, SO2)

This experiment was performed to study product formation from stabilized Criegee intermediates (SCI) in the Isoprene + ozone under various relative humidity (RH) conditions with cyclohexane as an OH scavenger. This investigates the reaction of the simplest SCI (CH2OO) with water and water dimer

Different Isoprene to ozone ratio. Significant amounts of CH2OO + H2O products (HMHP, formic acid, and H2O2) were observed

Experiment Details


  • Gas phase chemical reaction
Temperature: 24
Relative Humidity: 4
Seeded Experiment: No
Fuchs Adjusted Surface Area:
Condensation sink rate coefficient: 4
Reaction type:
Oxidant Name: Ozone
Initial Oxidant Concentration Value: 590 (parts_per_billion)
RO2 Main Fate: Not Sure
RO2 Lifetime: (Seconds)
Pressure: 750 Torr

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

Experiment Set Details

Name: Isoprene ozonolysis (various amounts of water, SO2)
Time format and units: Experiment time (minutes, local)
Investigations into the humidity-dependent ozonolysis of isoprene to form hydroxymethylhydroperoxide (HMHP), formic acid, and other products. The bimolecular fates of the C1 stabilized Criegee (CH2OO) was explored with water and SO2 to understand its competition in the atmosphere.


  • Tran Nguyen UC Davis
  • Paul Wennberg Caltech


Principal investigator:

John H Seinfeld
Phone: (626) 395-4635
E-mail: seinfeld@caltech.edu
OrcID: https://orcid.org/0000-0003-1344-4068

Data Manager:

Stephanie Kong
Phone: 626-395-3194
E-mail: wkong@caltech.edu


Reactant Compound type Concentration Concentration units
  • Alkene
99 Parts Per Billion
  • Alkane
50 Parts Per Million

131118_Timeline.csv Timeline

Local time (hh:mm) Action (Time zero is the time Isoprene is introduced)
13:58 Inject ozone (take ozone monitor off chamber)
15:05 Inject 5.5mL of cyclohexane as OH scavenger (approx 50 ppm)
15:58 Inject 10uL of isoprene or approx 100 ppb (reaction start)

Light Flux Characterizations:
Particle Loss Characterizations:
Vapor Loss Characterizations:
2016-05-11 (#10)

Chamber Details

Name: Near/Far Bag 2012-2015 (Tran)
Volume in cubic meters: 27
Shape: Rectangular Prism
Surface area in cubic meters: 41.8
Flow Mode: Batch
Flow through rate in liters per minute:
Body Material: Teflon
Body thickness: 50
Replacement date:
Replacement frequency: As needed
Cleaning method: Flushing with air
o3 background: 0.5 ppb
nox background: 0.1 ppb for Near, > 0.1 ppb for Far
Particle background in micrograms per cubic meter: < 0.1 ug/m3
Air filtration method: Custom Filter
Mixing method: 0
Mixing method material:
Temparature Control: Yes
Temparature measurements recorded: Yes
Temparature range (min degrees celcius): 20
Temparature range (max degrees celcius): 45
Humidity Control: Yes
Humidity Measurements Recorded: Yes
Relative humidity range (min percent): 5
Relative humidity range (max percent): 100
Particle experiment capability: 1
Lights: Yes
Light source type(s): UVA Black Lamps
Supplemental information: https://www.worldscientific.com/doi/abs/10.1142/9789813147355_0001
Additional Notes: