Crossed molecular beam studies of atmospheric chemical reaction dynamics

Thesis/Dissertation · Thu Apr 01 04:00:00 EST 1993

DOI:https://doi.org/10.2172/10179098· OSTI ID:10179098

Zhang, Jingsong ^[1]

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1. Univ. of California, Berkeley, CA (United States)

The dynamics of several elementary chemical reactions that are important in atmospheric chemistry are investigated. The reactive scattering of ground state chlorine or bromine atoms with ozone molecules and ground state chlorine atoms with nitrogen dioxide molecules is studied using a crossed molecular beams apparatus with a rotatable mass spectrometer detector. The Cl + O₃ → ClO + O₂ reaction has been studied at four collision energies ranging from 6 kcal/mole to 32 kcal/mole. The derived product center-of-mass angular and translational energy distributions show that the reaction has a direct reaction mechanism and that there is a strong repulsion on the exit channel. The ClO product is sideways and forward scattered with respect to the Cl atom, and the translational energy release is large. The Cl atom is most likely to attack the terminal oxygen atom of the ozone molecule. The Br + O₃ → ClO + O₂ reaction has been studied at five collision energies ranging from 5 kcal/mole to 26 kcal/mole. The derived product center-of-mass angular and translational energy distributions are quite similar to those in the Cl + O₃ reaction. The Br + O₃ reaction has a direct reaction mechanism similar to that of the Cl + O₃ reaction. The electronic structure of the ozone molecule seems to play the central role in determining the reaction mechanism in atomic radical reactions with the ozone molecule. The Cl + NO₂ → ClO + NO reaction has been studied at three collision energies ranging from 10.6 kcal/mole to 22.4 kcal/mole. The center-of-mass angular distribution has some forward-backward symmetry, and the product translational energy release is quite large. The reaction proceeds through a short-lived complex whose lifetime is less than one rotational period. The experimental results seem to show that the Cl atom mainly attacks the oxygen atom instead of the nitrogen atom of the NO₂ molecule.

• Research Organization: Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 10179098
• Report Number(s): LBL--34297; ON: DE93019246
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201
54 ENVIRONMENTAL SCIENCES
540120
ATMOSPHERIC CHEMISTRY
BROMINE
CENTER-OF-MASS SYSTEM
CHEMICAL AND PHYSICOCHEMICAL PROPERTIES
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CHEMICALS MONITORING AND TRANSPORT
CHLORINE
EXPERIMENTAL DATA
MASS SPECTRA
MOLECULAR BEAMS
NITROGEN DIOXIDE
OZONE