Effect of temperature on the dissociative electron attachment to CClF/sub 3/ and C/sub 2/F/sub 6/

Journal Article · Fri Mar 15 04:00:00 EST 1985 · J. Chem. Phys.; (United States)

OSTI ID:5923411

Spyrou, S M; Christophorou, L G

The total electron attachment rate constant k/sub a/() for CClF/sub 3/ and C/sub 2/F/sub 6/ has been meausured using an electron swarm technique in the mean electron energy range 0.41 to 4.81 eV and over the range of temperature T from 300 to 750 K. At each value of T the total electron attachment cross section sigma/sub a/(epsilon) was determined from the measured k/sub a/() using the swarm unfolding technique and was compared with the results of a mass spectrometric study. The sigma/sub a/(epsilon) for C/sub 2/F/sub 6/ shows a single peak (due to F/sup -/ and CF/sub 3//sup -/) which shifts from 3.9 eV at 300 K to approx.3.3 eV at 750 K. (The onset shifts correspondingly from 2.3 to 1.5 eV.) For CClF/sub 3/ the sigma/sub a/(epsilon) shows two peaks: at approx.1.5 eV (due to Cl/sup -/) and at approx.4.7 eV (due to Cl/sup -/, F/sup -/, CClF/sub 2//sup -/, and ClF/sup -/). The peak at approx.1.5 eV is especially sensitive to changes in T. The peak value of sigma/sub a/(epsilon) increased by a factor of approx.3, and the energy position of the peak and onset shifted to progressively lower energies when T increased from 300 to 700 K. The analysis of these results led us to conclude that the changes in k/sub a/() and sigma/sub a/(epsilon) for the dissociative attachment processes of these molecules with increasing T result from the increase with T of the total internal (approx. = vibrational) energy of the molecule.

• Research Organization: Atomic, Molecular, and High Voltage Physics Group, Health and Safety Research Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 5923411
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 82:6; ISSN JCPSA
• Country of Publication: United States
• Language: English

Related Subjects

640304* -- Atomic
Molecular & Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
CHEMICAL REACTION KINETICS
CHLORINATED ALIPHATIC HYDROCARBONS
COLLISIONS
DISSOCIATION
ELECTRON ATTACHMENT
ELECTRON COLLISIONS
ELECTRON-MOLECULE COLLISIONS
FLUORINATED ALIPHATIC HYDROCARBONS
HALOGENATED ALIPHATIC HYDROCARBONS
HIGH TEMPERATURE
KINETICS
MEDIUM TEMPERATURE
MOLECULE COLLISIONS
ORGANIC CHLORINE COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC FLUORINE COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
REACTION KINETICS
TEMPERATURE DEPENDENCE