Titre :

Direct Absolute Measurements of the Rate Constants of Unimolecular Decomposition of Acyl Radicals by Time Resolved Infrared Diode Laser Spectroscopy (CH3)3 CCO → (CH3)3C + CO(CH3)2CHCO → (CH3)2CH + CO (preliminary results)

Auteur(s) :

Hanoune, Benjamin [Auteur]
Physicochimie des Processus de Combustion et de l’Atmosphère - UMR 8522 [PC2A]
Elmaimouni, Lahcen [Auteur]
جامعة مولاي إسماعيل = Université Moulay Ismaïl [UMI]
Devolder, Pascal [Auteur]
Physicochimie des Processus de Combustion et de l’Atmosphère - UMR 8522 [PC2A]
Dusanter, Sébastien [Auteur]
Physicochimie des Processus de Combustion et de l’Atmosphère - UMR 8522 [PC2A]
Lemoine, Bernard [Auteur]
Laboratoire de Physique des Lasers, Atomes et Molécules - UMR 8523 [PhLAM]

Titre de la manifestation scientifique :

8th European Symposium on the Physico-Chemical Behavior of Atmospheric Pollutants

Ville :

Turin

Pays :

Italie

Date de début de la manifestation scientifique :

2001-09-17

Discipline(s) HAL :

Chimie/Chimie théorique et/ou physique

Résumé en anglais : [en]

Acyl radicals RCO are important intermediates formed after reaction of aldehydes with OH or NO3 radicals. Like most alkoxyl radicals, under atmospheric conditions, they can react via 3 different reaction pathways : ...
Lire la suite >Acyl radicals RCO are important intermediates formed after reaction of aldehydes with OH or NO3 radicals. Like most alkoxyl radicals, under atmospheric conditions, they can react via 3 different reaction pathways : unimolecular thermal decomposition, possibly in the fall-off range, isomerization, and reaction with O2. Since isomerization is negligible for small radicals, the ozone creating potential of acyl radicals is only determined by the ratio between decomposition and reaction with O2. Using our newly developed Pulsed Laser Photolysis / Tunable Diode Laser spectrometer (Hanoune et al. 2001), we have measured directly the decomposition rate constant of two acyl radicals (2,2-dimethylpropionyl or pivaloyl (CH3)3CCO, and isobutyryl (CH3)2CHCO), between 300 and 318 K and between 4.7 and 34 Torr. Reactions were monitored by probing the build-up of CO. It was found to be necessary to work in presence of O2 to avoid Cl regeneration. Our data complement the few existing measurements performed at higher pressure. Jagiella et al. (2000) measured the ratio between decomposition and O2 reaction in a photochemical reaction chamber combined with long-path FTIR analysis between 293 and 317 K at atmospheric pressure. Concurrently, Tomas et al. (2000) measured the same ratio by flash photolysis coupled to UV absorption spectrometry at atmospheric pressure between 323 and 453 K, with a few additional measurements in the fall-off domain (433 K, 40 and 150 Torr).Lire moins >

Langue :

Anglais

Comité de lecture :

Non

Audience :

Internationale

Vulgarisation :

Non

Collections :

• Laboratoire de Physique des Lasers, Atomes et Molécules (PhLAM) - UMR 8523

Source :

Harvested from HAL