Grantee Research Project Results
1999 Progress Report: RO2 and HOx Radicals in Urban and Rural Air: Measurements of OH and RO2 Formation From Ozone-Alkene Reactions, and the Rate Coefficients of the Reactions of High Molecular Weight RO2 Radicals with HO2
EPA Grant Number: R826236Title: RO2 and HOx Radicals in Urban and Rural Air: Measurements of OH and RO2 Formation From Ozone-Alkene Reactions, and the Rate Coefficients of the Reactions of High Molecular Weight RO2 Radicals with HO2
Investigators: Paulson, Suzanne , Sander, Stanley
Institution: University of California - Los Angeles
EPA Project Officer: Hahn, Intaek
Project Period: January 15, 1998 through January 14, 2001
Project Period Covered by this Report: January 15, 1999 through January 14, 2000
Project Amount: $440,323
RFA: Ambient Air Quality (1997) RFA Text | Recipients Lists
Research Category: Air Quality and Air Toxics , Air
Objective:
The objectives of this project, for the UCLA work component are to: (1) continue analysis of OH formation yield data and prepare publications; and (2) build and characterize an HPLC system to provide the ability to measure peroxides to address Goal 3, measurement of RO2 yields. Measurements of peroxide formation were to begin. The objectives for the JPL work component are to: (1) continue development of the Infrared Kinetic Spectroscopy (IRKS) system which will be used to study the rates and mechanisms of reactions between organic peroxy radicals (RO2) and hydroperoxyl (HO2) radicals; and (2) carry out kinetics measurements on the recombination reaction, HO2 + NO2 + M ? HO2NO2 + M, as a diagnostic for the performance of the IRKS system.Progress Summary:
During the reporting period, the following milestones were reached for the UCLA work component:
- The OH formation yield work during this period resulted in two publications, detailing results for cyclopentene, cyclohexene, and cycloheptene and butadiene. The original goals were expanded upon to include a study of the production of toxic epoxides from butadiene together with OH formation and other aspects of the butadiene oxidation mechanism. We also forged a collaboration with K.N. Houk to perform ab-initio calculations, which have led to the first results to provide insight into the step of ozone-alkene reactions that controls OH production, a process that is highly sensitive to the structure of the alkene.
- Assembly of the HPLC-fluorescence system to develop the ability to measure peroxides to address Goal 3, measurement of RO2 yields, together with characterization of the flow tube to perform these measurements, was completed, and results are forthcoming. The detection limit for peroxides with three or fewer carbons using the HPLC system is about 100 ppt.
- A new temperature-controllable reaction cell was installed. This cell permits kinetic measurements to be made over the temperature range 220?373 K. In order to achieve uniform temperature control, the carrier gas is pre-cooled in a sidearm. Temperature uniformity is maintained to within 1 C. A purge gas system is used in the mirror mounting blocks to minimize contamination of the Herriott mirrors and precisely constrain the temperature-controlled region in the cell.
- A comprehensive kinetics study of the HO2 + NO2 + M reaction was carried out. The temperature and pressure dependences of the reaction rate coefficient were measured over the range 225-298 K and 20-150 Torr of N2. The results are consistent with previous studies, but are more precise and accurate due to the improved detection limit for HO2 and the ability to measure the concentration of NO2 inside the reaction volume by uv-visible spectrophotometry.
Future Activities:
The activities for the final period include completion of the final publication for OH yield measurements, detailing results for cis and trans-2-butene, cis and trans-2-pentene, cis and trans-2-hexene, 2-methyl-2-butene, styrene, a-methyl styrene, and trans-b-methyl styrene (Goal 1). A study of the rates and mechanisms of reactions between organic peroxy radicals (RO2) and hydroperoxyl (HO2) radicals using the IRKS system will be completed (Goal 2). A systematic investigation of hydrogen peroxide formation yields for a series of anthropogenic and biogenic alkenes will be carried out, as well as an investigation of peroxyl radical yields from ozone-alkene reactions (Goal 3).Journal Articles on this Report : 1 Displayed | Download in RIS Format
| Other project views: | All 30 publications | 10 publications in selected types | All 10 journal articles |
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Fenske JD, Kuwata KT, Houk KN, Paulson SE. OH radical yields from the ozone reaction with cycloalkenes. Journal of Physical Chemistry A 2000;104(31):7246-7254. |
R826236 (1999) R826236 (Final) |
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Supplemental Keywords:
atmospheric chemistry, organic radicals, hydroxyl radical., RFA, Scientific Discipline, Air, particulate matter, air toxics, Environmental Chemistry, tropospheric ozone, Atmospheric Sciences, Environmental Engineering, ambient air quality, urban air toxics, particle size, particulates, ozone-alkene reactions, air pollutants, chemical characteristics, ozone occurrence, photochemical radical, ambient air, ozone, ambient measurement methods, ambient monitoring, chemical composition, smog, urban air pollutants, photochemical smog, atmosphere, infrared spectroscopy, chain reactions, Volatile Organic Compounds (VOCs), Alkene reactions, photochemical assessmentRelevant Websites:
http://dx.doi.org/10.1021/jp993611qProgress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.