Experiment: Caltech Atmospheric Chamber_20140822_ISOPRENE/CYCLOHEXANE/sulfur dioxide_Ozone_No Seed_RH19


Name: Caltech Atmospheric Chamber_20140822_ISOPRENE/CYCLOHEXANE/sulfur dioxide_Ozone_No Seed_RH19
Date: 2014-08-22

Caltech Atmospheric Chamber

Near/Far Bag 2012-2015 (Tran)

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

This experiment was performed to study the competition between the reactions of the smallest stabilized Criegee intermediate (SCI) CH2OO with water (or water dimer) and SO2

At 19% RH and 15 ppb SO2, there was low sulfate particle formation as seen by the AMS

Experiment Details


  • Gas phase chemical reaction
Temperature: 24
Relative Humidity: 19
Seeded Experiment: No
Fuchs Adjusted Surface Area:
Condensation sink rate coefficient: 19
Reaction type:
Oxidant Name: Ozone
Initial Oxidant Concentration Value: 120 (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
22 Parts Per Billion
  • Alkane
10 Parts Per Million
sulfur dioxide (1119) 15 Parts Per Billion

140822_Timeline.csv Timeline

Local time (hh:mm) Action (Time zero is the time Isoprene is introduced)
11:45 Inject water vapor
11:50 Inject ozone for 20 minutes and flush for 10 minutes
12:25 Inject 1.1mL of cyclohexane (appox 10 ppm)
12:35 Stop injecting cyclohexane (purge SO2 tank)
12:43 Inject SO2 for 7min at 5slm and flush for 15 min (approx 15ppb)
13:13 Inject 2uL (approx 20 ppb) of isoprene (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: