Experiment: Caltech Atmospheric Chamber_20140724_Methacrylolyl peroxynitrate(MPAN)/ALPHA-PINENE/hydrogen peroxide/Methacrylic acid epoxide (MAE)_Hydroxyl radical_No Seed_Dry


Name: Caltech Atmospheric Chamber_20140724_Methacrylolyl peroxynitrate(MPAN)/ALPHA-PINENE/hydrogen peroxide/Methacrylic acid epoxide (MAE)_Hydroxyl radical_No Seed_Dry
Date: 2014-07-24

Caltech Atmospheric Chamber

Near/Far Bag 2012-2015 (Tran)

Experiment Set
MPAN, Methacrolein, Isobutyraldehyde, and 231MBO photoxidation experiments

This experiment was done to photooxidize MPAN and capture NO3 with a-pinene, while observing secondary organic aerosol (SOA) formation through dry nucleation. MAE was added toward the end of the experiment to see if it enhanced SOA formation.

Addition of MAE didn't change the particle mass. Similar to 7/22 - we observed m/z316, the pinene nitroxyhydroperoxide on CIMS, which showed that NO3 radical was liberated from the MPAN+OH reaction. This reaction produced a lot of SOA.

Additional Notes
Equivalent to Exp#5 in the PCCP paper.

Experiment Details


  • Gas phase chemical reaction
  • Aerosol formation
Temperature: 15
Relative Humidity: 4
Seeded Experiment: No
Fuchs Adjusted Surface Area:
Condensation sink rate coefficient: 4
Reaction type:
Oxidant Name: Hydroxyl radical
Initial Oxidant Concentration Value: 1.5e6 (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: MPAN, Methacrolein, Isobutyraldehyde, and 231MBO photoxidation experiments
Time format and units: Experiment time (minutes, local)
Photoxidation of synthesized methacryloyl peroxynitrate (MPAN) to understand its pathways of SOA formation, leading to 2-methylglyceric acid in the particle phase. It is hypothesized that MPAN produces an unstable intermediate called HMML (hydroxymethyl methyl-a-lactone) that ring opens when it hits a surface, with co-product NO3. Some experiments were done with alpha-pinene as an NO3 scavenger, with the production of pinene nitroxy hydroperoxide (PNP, m/z 316 C10H17NO5) evidence of the alpha-pinene + NO3 chemistry. Photoxidation of methacrolein (MACR) was performed for comparison. Photooxidation of 2-methyl-but-3-ene-1-ol (231MBO) and isobutyraldehyde were performed because they are (or can produce) analogous compounds that will give insight into the oxidation mechanism. Experiments were mainly performed dry and with no seeds, although 2 experiments were performed on with varying particle liquid water on ammonium sulfate (AS) seeds. Note that particle wall loss has already been applied to SMPS data, but the raw data are also provided as well as the wall loss kinetic parameters.


  • 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
Methacrylolyl peroxynitrate(MPAN)
  • Alkene
15 Parts Per Billion
  • Alkene
30 Parts Per Billion
hydrogen peroxide (784)
  • Hydroperoxide
2 Parts Per Million
Methacrylic acid epoxide (MAE)
  • Organic acid
  • epoxide
15 Parts Per Billion

140724_Timeline.csv Timeline

Local time (hh:mm) Action (Time zero is "Lights On" time)
9:25 Chilling chamber to 15degC
9:35 Started instruments
10:15 chamber temperature is stable at 15degC
11:17 Injecting H2O2 (110 uL)
12:20 Injecting alpha-pinene (6.5 uL)
12:45 Stop injection
12:55 Injecting MPAN in tridecane (solution at 0degC)
14:00 Stop MPAN injections
14:26 Lights on 100%
17:45 Lights off (wait in the dark to stabilize)
19:05 Inject MAE (methacrylic acid epoxide)
19:35 Stopped MAE injection
21:05 collect filter for SOA analysis
24:30:00 filter collection ended (flush chamber)

Light Flux Characterizations:
2013-12-13 (#28)
Particle Loss Characterizations:
2013-03-06 (#29)
Vapor Loss Characterizations:

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: