Experiment: Nguyen Group_20220713_Ocimene/Ammonium Sulfate/Ozone/Hydrogen Peroxide_Ozone_Ammonium sulfate
Experiment
Name: Nguyen Group_20220713_Ocimene/Ammonium Sulfate/Ozone/Hydrogen Peroxide_Ozone_Ammonium sulfate
Date: 2022-07-13
Organization
Nguyen Group
Chamber
Tran's big bag of air
Experiment Set
Terpene nighttime chemistry
Goals
To quantify SOA yield and gas-phase product yields from humid ozonolysis of b-ocimene, which will serve as a "control" experiment to subtract the ozonolysis contribution to the nighttime chemistry of b-ocimene as measured in the experiment on 7/15/22.
Summary
The chamber was humidified, after which H2O2, and O3 were injected in the chamber and allowed to equilibrate. Ammonium sulfate seed particles were injected. Then b-ocimene was injected and decayed by reaction with ozone (plus some contribution from OH). Gas phase organics were monitored by CF3O- CIMS (units: normalized counts), particle formation was monitored by SMPS, and RH/T/O3/NOx were monitored throughout. O3/NOx data sometimes require post-correction not applied here, including subtraction of an ozone interference from H2O2 (1 ppm H2O2 is detected as about 12 ppb ozone) and correction for an in-line HEPA filter (see timeline for applicable timing) that scrubs about 10% of NO2 and 45% of ozone.Experiment Details
Categories:
- Gas phase chemical reaction
- Aerosol formation
Relative Humidity: 67
Seeded Experiment: Yes
Type of Seed: Ammonium sulfate
Initial Seed Concentration Value: 300
Seed Concentration Units: micrograms_per_cubic_meter
Fuchs Adjusted Surface Area:
Condensation sink rate coefficient: 67
Reaction type:
Oxidant Name: Ozone
Initial Oxidant Concentration Value: 115 (parts_per_billion)
RO2 Main Fate: Not Sure
RO2 Lifetime: (Seconds)
Pressure: approx 1 atm
Data Set plots
Experiment Set Details
Name: Terpene nighttime chemistry
Time format and units: HH:MM
Description:
A series of experiments examining product yields and SOA formation from terpene + NO3 reactions under conditions designed to mimic the nighttime atmosphere of the Southeast US in the summer. Two types of experiments are included: (1) those in which the chemistry is initiated by additions of O3 + NO2 + H2O2, which together provide conditions closely resembling the ambient atmosphere at night (i.e., with NO3 + terpene as the dominant oxidation reaction but some O3 + terpene contribution, and with RO2 + HO2 as the dominant peroxy radical fate but an appreciable contribution from RO2 + RO2), and (2) equivalent experiments performed without NO2 as a control, so as to isolate the terpene + O3 chemistry. SOA yield experiments are performed at approximately 60% RH with hydrated ammonium sulfate seed aerosol. Filter collection experiments are performed without ammonium sulfate seed aerosol, using very high terpene loadings so as to acquire enough material for offline analysis, and using N2O5 as the NO3 precursor. Data include RH/T, particle size distributions measured by SMPS (including wall-loss corrected and un-corrected data), gas-phase organic species monitored by CF3O- CIMS, and O3 & NOx concentrations. CIMS computer was struggling during this experiment set, so some experiments may be missing data when it abruptly stopped.
Collaborators:
Contacts
Principal investigator:
Tran B. Nguyen
Phone: 5307525987
E-mail: tbn@ucdavis.edu
OrcID: 0000-0001-9206-4359
Data Manager:
Kelvin H. Bates
E-mail: kelvinhbates@gmail.com
220713_timeline.csv
Timeline
| Time_HH:MM_local | Action |
| 8:51 | Start humidifying |
| 8:52 | NOx/O3/RH/T monitors on |
| 9:19 | SMPS on |
| 9:23 | Stop humidifying |
| 9:25 | Inject ozone for 105 seconds followed by mixing air bursts |
| 9:27 | Start H2O2 injection (100 uL of 50% w/w in H2O; 4 slm air; heated to 40 C) |
| 9:28 | Start atomization (0.29 g (NH4)2SO4 in 100 mL MilliQ H2O; 35 psi N2; heater wet-wall denuder to hydrate particles) |
| 9:37 | CIMS on |
| 9:51 | HEPA filter on NOx/O3 monitors |
| 9:52 | Stop atomization and H2O2 injection; mixing air bursts |
| 10:20 | Start ocimene injection (1.7 uL blown in with 4 slm air over 20 min with mixing air bursts every 5 min) |
| 13:00 | HEPA filter off NOx/O3 monitors |
| 16:00 | Instruments shut down and uploaded; flush chamber |
Citations
Characterizations
(None)
Particle Loss Characterizations:
2022-07-25 (#37)
Vapor Loss Characterizations:
(None)
Chamber Details
Name: Tran's big bag of air
Volume in cubic meters: 10
Shape: Rectangular Prism
Surface area in cubic meters: 28
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:
Particle background in micrograms per cubic meter:
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):
Temparature range (max degrees celcius):
Humidity Control: Yes
Humidity Measurements Recorded: Yes
Relative humidity range (min percent):
Relative humidity range (max percent):
Particle experiment capability: 1
Lights: Yes
Light source type(s):
UV broadband black lights (centered at 350 nm)
Supplemental information:
Additional Notes: 40-Watt, Osram/Sylvania 350nm black lights, 48” long, T12 fluorescent; 72 bulbs, 36 each on two facing walls, with UV-reflective siding on all walls. Lights are controlled via 6 panels (3 on the right wall - top, mid, bottom - and 3 equivalent on the left wall).