Photochemical kinetics of excited states of O sub 3 and O sub 2 : Laboratory studies and atmospheric implications

Thesis/Dissertation · Tue Jan 01 04:00:00 EST 1991

OSTI ID:5019675

Shi, Jichun

In this dissertation, the photochemical kinetics of these excited species have been studied in a series of laboratory measurements, which are divided into two groups: (1) the study of the excited intermediates formed in the ozone recombination reaction, and (2) the investigation of the unusual odd oxygen formation in O{sub 2} under laser irradiation at 248 nm. The ozone recombination reaction has been investigated at room temperature by monitoring the time-resolved infrared chemiluminescence of ozone at 9.6 {mu}m, 4.7 {mu}m, and 3.4 {mu}m. These studies have indicated that the recombination reaction (O + O{sub 2} + M) apparently proceeds through an intermediate complex OM, and, for M = O{sub 2}, the recombination also involves the participation of a metastable electronic state, O{sub 3}(E). The three infrared emissions have also been used to analyze the deactivation of vibrationally excited O{sub 3}(v). The unusual odd oxygen formation in O{sub 2} at 248 nm has been studied in both pure O{sub 2} and O{sub 2} + N{sub 2} and O{sub 2} + Ar mixtures at pressures between 200 and 1,600 torr and at temperatures between 298 and 370K. The results have indicated that this odd oxygen formation is initiated by O{sub 2} absorption in the Herzberg continuum, and it is autocatalytically accelerated by the photodissociation of vibrationally excited O{sub 2}(v) at 248 nm. These kinetics results have been used to study the possible roles of excited O{sub 3} and O{sub 2} species in the sources and sinks of odd oxygen at 90-120 km, and in the heavy ozone isotope enhancement in the stratosphere.

• Research Organization: Michigan Univ., Ann Arbor, MI (United States)
• OSTI ID: 5019675
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540120* -- Environment
Atmospheric-- Chemicals Monitoring & Transport-- (1990-)
AIR POLLUTION
ATMOSPHERIC CHEMISTRY
CHEMICAL REACTIONS
CHEMILUMINESCENCE
CHEMISTRY
ELECTROMAGNETIC RADIATION
ELEMENTS
LASER RADIATION
LUMINESCENCE
NONMETALS
OXYGEN
OZONE
PHOTOCHEMICAL REACTIONS
POLLUTION
RADIATIONS