Dynamics of Ba-Br sub 2 chemiionization reactions
- Lawrence Berkeley Lab., CA (United States)
The formation of BaBr{sup +} ions in reaction of Ba({sup 1}S{sub 0},{sup 1}P{sub 1}) with Br{sub 2} was studied as a function of laboratory scattering angle and product translational energy in a crossed-beam experiment. The contour map of BaBr{sup +} flux obtained for the ground-state reaction at 1.1-eV collision energy showed a backscattered angular distribution (relative to the barium beam) with a substantial fraction of the available energy appearing in translation. Laser excitation strongly inhibited this channel at 1.1 eV. These experimental observations suggest that for the chemiion reaction head-on, collinear collisions and proximal crossings of the potential energy surfaces are necessary to preclude escape into the dominant neutral pathways. At 1.6-eV collision energy potential energy surfaces are necessary to preclude escape into the dominant neutral pathways. At 1.6-eV collision energy a new laser-dependent source of BaBr{sup +} appeared. This laser-enhanced BaBr{sup +} showed a laboratory angular distribution substantially narrower than for the ground-state reaction, indicating a smaller translational energy release. The angular distribution was {approximately}70% backscattered and displayed a clear dip at the center of mass. This new BaBr{sup +}, produced from electronically excited barium at higher translational energy, is ascribed to secondary collisions of BaBr+Br initially formed in low impact parameter collisions. Reaction of electronically excited barium with Br{sub 2} also yielded an associative ionization product BaBr{sub 2}{sup +} at both collision energies studied, with a cross section about 1/100th that of the chemiion channel.
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 7273943
- Journal Information:
- Journal of Physical Chemistry; (United States), Vol. 95:21; ISSN 0022-3654
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
BARIUM
ATOM-ATOM COLLISIONS
BROMINE
ANGULAR DISTRIBUTION
CHEMICAL REACTIONS
DYNAMICS
ENERGY SPECTRA
EXCITED STATES
EXPERIMENTAL DATA
GROUND STATES
LASER RADIATION
SCATTERING
ALKALINE EARTH METALS
ATOM COLLISIONS
COLLISIONS
DATA
DISTRIBUTION
ELECTROMAGNETIC RADIATION
ELEMENTS
ENERGY LEVELS
HALOGENS
INFORMATION
MECHANICS
METALS
NONMETALS
NUMERICAL DATA
RADIATIONS
SPECTRA
400201* - Chemical & Physicochemical Properties