Experimental and theoretical studies of reactions of halogenated species of atmospheric interest
This dissertation presents the results of experimental and theoretical studies of halogenated species and reactions of atmospheric interest. Ab initio calculations have been used with isogyric and isodesmic schemes to evaluate the heats of formation for species such as HCO, FCO, HFCO, HClCO, HO[sub 2], FO and FO[sub 2]. The calculated values have proven reliable by comparison with available experimental data. Ab initio calculations have also been used to examine the main features of the potential energy surface of complicated reaction systems. Calculations on the FCO + O[sub 2] [yields] FC(O)O[sub 2] reaction system predict that this reaction is thermodynamically and kinetically the preferred pathway. This result leads to the postulation of an ozone regenerating catalytic cycle. Theoretical examinations of dissociation pathways of the HXCO (where X = F, Cl and Br) show that the molecular elimination of HX is the lowest energy pathway. The reaction F + HFCO and multiphoton dissociation of FBrCO molecule have been studied for the laboratory generation of FCO radicals. The rate coefficient for the reaction F + HFCO [yields] HF + FCO has been determined as k (T) = (4.4 [+-] 2.6) [times] 10[sup [minus]11] exp[[minus](1800 [+-] 400/RT)] cm[sup 3] molecule[sup [minus]1]s[sup [minus]1] over 298-368 K range by the IRMPD/chemiluminesence technique. FCO radicals produced are predicted theoretically to undergo rapid reaction via FCO + FCO [yields] F[sub 2]CO + CO through a hot F[sub 2]C[sub 2]O[sub 2]. The threshold intensity for the photolysis of FBrCO by a CO[sub 2] laser is estimated to be 143.4 [+-] 15 MW cm[sup [minus]2] and the favorable path of FBrCO dissociation is the formation of Br and FCO. The reaction system of F + CH[sub 4] has been studied using the IRMPD/LIF technique with the aid of theoretical calculated energetics for major secondary reactions.
- Research Organization:
- Wayne State Univ., Detroit, MI (United States)
- OSTI ID:
- 6958907
- Resource Relation:
- Other Information: Thesis (Ph.D.)
- Country of Publication:
- United States
- Language:
- English
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ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
54 ENVIRONMENTAL SCIENCES
HALOGEN COMPOUNDS
CHEMICAL REACTION KINETICS
ORGANIC HALOGEN COMPOUNDS
RADICALS
ATMOSPHERIC CHEMISTRY
EARTH ATMOSPHERE
MATHEMATICAL MODELS
CHEMISTRY
KINETICS
ORGANIC COMPOUNDS
REACTION KINETICS
400201* - Chemical & Physicochemical Properties
540120 - Environment
Atmospheric- Chemicals Monitoring & Transport- (1990-)