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HO(2) formation from the OH + benzene reaction in the presence of O(2).
MedLine Citation:
PMID:  21544290     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
In this study we investigated the secondary formation of HO(2) following the benzene + OH reaction in N(2) with variable O(2) content at atmospheric pressure and room temperature in the absence of NO. After pulsed formation of OH, HO(x) (= OH + HO(2)) and OH decay curves were measured by means of a laser-induced fluorescence technique (LIF). In synthetic air the total HO(2) yield was determined to be 0.69 ± 0.10 by comparison to results obtained with CO as a reference compound. HO(2) is expected to be a direct product of the reaction of the intermediately formed OH-benzene adduct with O(2). The HO(2) yield is slightly greater than the currently recommended yield of the proposed HO(2) co-product phenol (∼53%). This hints towards other, minor HO(2) forming channels in the absence of NO, e.g. the formation of epoxide species that was proposed in the literature. For other test compounds upper limits of HO(2) yields of 0.10 (isoprene) and 0.05 (cyclohexane) were obtained, respectively. In further experiments at low O(2) concentrations (0.06-0.14% in N(2)) rate constants of (2.4 ± 1.1) × 10(-16) cm(3) s(-1) and (5.6 ± 1.1) × 10(-12) cm(3) s(-1) were estimated for the OH-benzene adduct reactions with O(2) and O(3), respectively. The rate constant of the unimolecular dissociation of the adduct back to benzene + OH was determined to be (3.9 ± 1.3) s(-1). The HO(2) yield at low O(2) was similar to that found in synthetic air, independent of O(2) and O(3) concentrations indicating comparable HO(2) yields for the adduct + O(2) and adduct + O(3) reactions.
Authors:
Sascha Nehr; Birger Bohn; Hendrik Fuchs; Andreas Hofzumahaus; Andreas Wahner
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2011-5-4
Journal Detail:
Title:  Physical chemistry chemical physics : PCCP     Volume:  -     ISSN:  1463-9084     ISO Abbreviation:  -     Publication Date:  2011 May 
Date Detail:
Created Date:  2011-5-5     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  100888160     Medline TA:  Phys Chem Chem Phys     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Affiliation:
Institut für Energie- und Klimaforschung IEK-8: Troposphäre, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany. b.bohn@fz-juelich.de.
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