Attachment of slow electrons to hexafluorobenzene

Journal Article · Fri Oct 15 04:00:00 EDT 1976 · J. Chem. Phys.; (United States)

DOI:https://doi.org/10.1063/1.433534· OSTI ID:7350752

Gant, K S; Christophorou, L G

Slow (approximately-less-than 3 eV) electrons attach to hexafluorobenzene (C/sub 6/F/sub 6/) nondissociatively with large cross sections via two distinct processes, one at approx.0.0 eV and another peaking at 0.73 eV. The absolute rates and cross sections have been determined as a function of electron energy for both processes and are reported. At 0.03 and 0.73 eV the cross sections are 1.23 x 10/sup -14/ and 8.04 x 10/sup -16/ cm/sup 2/, respectively; the thermal (T=297degreeK) value of the attachment rate is 3.3 x 10/sup 9/ sec/sup -1/ torr/sup -1/(=1.02 x 10/sup -7/ sec/sup -1/ molecule/sup -1/ cm/sup 3/). The lifetime tau of C/sub 6/F/sub 6//sup -/* at approx.0.0 eV is approx.12 ..mu..sec, but at 0.73 eV it is much shorter, 10/sup -8/approximately-less-thantau<10/sup -6/ sec. The approx.0.0 eV process is associated with electron capture into the degenerate ..pi../sub 4/ and ..pi../sub 5/ molecular orbitals and is ascribed to the configurations ..pi../sup 2//sub 1/..pi../sup 2//sub 2/..pi../sup 2//sub 3/..pi../sup 1//sub 4/ and ..pi../sup 2//sub 1/..pi../sup 2//sub 2/..pi../sup 2//sub 3/..pi../sup 1//sub 5/, while the 0.73 eV process is associated with electron capture into the ..pi../sub 6/ orbital and is ascribed to the configuration ..pi../sup 2//sub 1/..pi../sup 2//sub 2/..pi../sup 2//sub 3/..pi../sup 1//sub 6/. For both C/sub 6/H/sub 6/ and C/sub 6/F/sub 6/ a relationship is shown to exist between the ionization energies of the occupied ..pi../sub 1/ and ..pi../sub 2/, ..pi../sub 3/ orbitals and the position of the negative ion (shape) resonances associated with the unoccupied ..pi../sub 4/, ..pi../sub 5/, and ..pi../sub 6/ orbitals. The observed large attachment rates for C/sub 6/F/sub 6/ extending from thermal energies to approximately-greater-than3 eV recommend it as a potential ''additive'' in high-voltage multicomponent gaseous insulators. (AIP)

• Research Organization: Health Physics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830
• OSTI ID: 7350752
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 65:8; ISSN JCPSA
• Country of Publication: United States
• Language: English

Related Subjects

640304* -- Atomic
Molecular &amp; Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
AROMATICS
COLLISIONS
CROSS SECTIONS
ELECTRON ATTACHMENT
ELECTRON COLLISIONS
ELECTRON-MOLECULE COLLISIONS
FLUORINATED AROMATIC HYDROCARBONS
HALOGENATED AROMATIC HYDROCARBONS
IONIZATION
MOLECULE COLLISIONS
ORGANIC COMPOUNDS
ORGANIC FLUORINE COMPOUNDS
ORGANIC HALOGEN COMPOUNDS