ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
Dissociative electron attachment to the brominated methanes CH2Br2, CHClBr2, and CCl3Br is investigated by measuring the velocity and angular distributions of negative ions produced through electron transfer in collisions with velocity selected K(np) Rydberg atoms. The data are analyzed with the aid of a Monte Carlo collision code that models the detailed kinematics of the reactions. Measurements with CH2Br2 show that essentially all the excess energy of reaction appears in translation, indicating that the electron is captured directly into an antibonding orbital. Data for CHClBr2 show that reaction proceeds by two channels: in the first, essentially all the excess energy appears in translation; in the second, limited conversion of the excess energy to internal motions occurs, pointing to a CHClBr2−* intermediate lifetime of ∼0.1 to 1 ps. In the case of CCl3Br, electron transfer leads to the formation of both Br− and Cl− ions. Br− production is again associated with two channels: in one, essentially all the excess energy appears in translation; in the other, near statistical redistribution of the excess energy occurs prior to dissociation, pointing to a relatively long-lived (τ∼several ps) CCl3Br−* intermediate. Data for Cl− production suggest only limited energy transfer to internal motions. Possible reaction mechanisms for the various channels are discussed with the aid of ab initio calculations. © 1998 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.477553
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