Formation and reactions of singlet oxygen, O[sub 2]([sup 1][Delta]g), under atmospheric conditions
Singlet molecular oxygen, O[sub 2]([sup 1][Delta][sub g]), plays a significant role in photochemical air pollution as a reactive and a deleterious oxidant. Gas phase O[sub 2]([sup 1][Delta][sub g]) formation by homogeneous photosensitization at atmospheric pressure was studied using a variety of compounds found in the atmosphere. The formation of O[sub 2]([sup 1][Delta][sub g]) was demonstrated by observing its 1.27 [mu]m emission using a liquid nitrogen-cooled germanium photodiode detector, and by performing chemical trapping studies with 2,3-dimethyl-2-butene (TME) and quenching studies with triethylamine (TEA). The factors affecting O[sub 2]([sup 1][Delta][sub g]) formation included sensitizer concentration, gas composition (%N[sub 2]/%O[sub 2]), total gas flow rate, irradiation wavelength, and light intensity. The disappearance of seven polycyclic aromatic hydrocarbons (PAHs) adsorbed on zeolite particles was studied under simulated atmospheric conditions. Benzo[ghi]perylene, chrysene, and benzo[e]pyrene were less susceptible to photooxidation than benz[a]anthracene (B[a]A), pyrene, dibenz[ah]anthracene, and benzo[a]pyrene. The disappearance of B[a]A in the presence of light and air involved a self-sensitized photooxidation with the formation of O[sub 2]([sup 1][Delta][sub g]) as a major process. These studies were directed at identifying viable processes for forming atmospheric O[sub 2]([sup 1][Delta][sub g]) and deleterious substances that might be formed when environmental pollutants react with O[sub 2]([sup 1][Delta][sub g]).
- Research Organization:
- Illinois Inst. of Tech., Chicago, IL (United States)
- OSTI ID:
- 7207250
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400500 -- Photochemistry
54 ENVIRONMENTAL SCIENCES
540120* -- Environment
Atmospheric-- Chemicals Monitoring & Transport-- (1990-)
AROMATICS
ATMOSPHERIC CHEMISTRY
CHARGED PARTICLES
CHEMICAL REACTIONS
CHEMISTRY
ELEMENTS
HYDROCARBONS
IONS
MOLECULAR IONS
NONMETALS
ORGANIC COMPOUNDS
OXYGEN
PHOTOCHEMICAL REACTIONS
POLYCYCLIC AROMATIC HYDROCARBONS