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Nitrate radical quantum yield from peroxyacetyl nitrate photolysis
Bradley A Flowers1, Mark E Angerhofer, William R Simpson
1Department of Chemistry and Geophysical Institute, University of Alaska, Fairbanks, Fairbanks, Alaska 99775-6160, USA.
The Journal of Physical Chemistry. A
|July 13, 2006
Summary
Photochemical reactions destroy peroxyacetyl nitrate (PAN). This study measured the nitrate radical quantum yield from PAN photolysis at 289 nm, finding it to be 0.31 +/- 0.08.
Area of Science:
- Atmospheric chemistry
- Photochemistry
- Environmental science
Background:
- Peroxyacetyl nitrate (PAN) is a widespread atmospheric pollutant.
- PAN is removed from the atmosphere via thermal and photochemical degradation pathways.
- Understanding PAN photolysis is crucial for atmospheric modeling and air quality assessments.
Purpose of the Study:
- To investigate the photochemical destruction mechanisms of PAN.
- To determine the quantum yield of nitrate radical (NO3) formation from PAN photolysis.
- To characterize the photoproducts resulting from PAN photodegradation.
Main Methods:
- Laser pulsed photolysis was employed to initiate PAN dissociation.
- Cavity ring-down spectroscopy was used for sensitive detection of the NO3 photoproduct.
- The NO3 quantum yield was determined relative to dinitrogen pentoxide (N2O5) under controlled experimental conditions.
Main Results:
- The nitrate radical (NO3) quantum yield from 289 nm photolysis of PAN was measured as Phi(NO3)PAN = 0.31 +/- 0.08.
- This measurement was performed relative to N2O5, assuming a unity quantum yield for NO3 formation from N2O5 photolysis.
- Detailed characterization of the experimental setup, including the optical cavity and photolysis system, was conducted.
Conclusions:
- The study provides a key quantitative measurement for the photochemical fate of PAN.
- The determined NO3 quantum yield is essential data for atmospheric chemistry models.
- Accurate understanding of PAN photolysis contributes to improved air quality predictions and pollution control strategies.
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