Experiment: Caltech Atmospheric Chamber_20130410_trans-beta IEPOX/hydrogen peroxide_Hydroxyl radical_Ammonium sulfate


Name: Caltech Atmospheric Chamber_20130410_trans-beta IEPOX/hydrogen peroxide_Hydroxyl radical_Ammonium sulfate
Date: 2013-04-10

Caltech Atmospheric Chamber

Near/Far Bag 2012-2015 (Tran)

Experiment Set
IEPOX uptake experiments

IEPOX was introduced to hydrated ammonium sulfate at 50% RH, the chamber was cooled to to remove the IEPOX from the gas phase (no more traces in CIMS); this increased the RH to ~80%) then H2O2 was added and lights turned on to photolyze the IEPOX on the particles and walls.

The organic aerosol as seen on AMS reacted nearly all away. Fragmentation products such as hydroxyacetone, glycolaldehyde, formic acid, acetic acid, and peroxyacetic acid were seen as products on CIMS

Additional Notes
Note that this experiment needs a chamber blank to subtract out the gas phase oxygenated voc formation from the walls.

Experiment Details


  • Condensed-phase chemical reaction
  • Multiphase chemical reaction
Temperature: 16-22
Relative Humidity: 50-83
Seeded Experiment: Yes
Type of Seed: Ammonium sulfate
Initial Seed Concentration Value: 93
Seed Concentration Units: micrograms_per_cubic_meter
Fuchs Adjusted Surface Area:
Condensation sink rate coefficient: 50-83
Reaction type:
Oxidant Name: Hydroxyl radical
Initial Oxidant Concentration Value: 1.5e6 (parts_per_billion)
RO2 Main Fate: HO2
RO2 Lifetime: (Seconds)
Pressure: 750 Torr

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

Experiment Set Details

Name: IEPOX uptake experiments
Time format and units: Experiment time (minutes, local)
Reactive uptake of cis and trans beta-IEPOX (isoprene epoxydiols with the epoxide in the 2-position, and the -CH2OH in the cis and trans conformations) onto dry and hydrated seeds of ammonium sulfate (AS), as well as other inorganic seeds. Note that wall loss is already applied to AMS particle data.


  • Tran B Nguyen UC Davis
  • Paul O 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
trans-beta IEPOX 15 Parts Per Billion
hydrogen peroxide (784) 2 Parts Per Million

130410_Timeline.csv Timeline

Local time (hh:mm) Action
12:15 Inject seed particles and mix air (chamber AT 50% RH)
12:55 Stop injecting seeds
13:15 (time 0) Inject IEPOX from a heated (~ 65 Celsius) glass bulb
15:15 Stop IEPOX injection
18:10 Decrease temperature to 16 Celsius; chamber RH went up to 77%
19:45 Injected 100uL or 2ppm theoretical of H2O2
20:45 Stop injection of H2O2
21:30 Lights on 100% intensity (RH is now 83%)

Light Flux Characterizations:
2013-12-13 (#28)
Particle Loss Characterizations:
Vapor Loss Characterizations:
2013-04-03 (#9)

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: