Study of the isomeric dependence of low-energy (<10 eV) electron attachment: Perfluoroalkanes

Journal Article · Mon Jul 15 04:00:00 EDT 1985 · J. Chem. Phys.; (United States)

DOI:https://doi.org/10.1063/1.449532· OSTI ID:5646039

Spyrou, S M; Hunter, S R; Christophorou, L G

The attachment of low-energy (<10 eV) electrons to the open-chain i-C/sub 4/F/sub 10/, i-C/sub 5/F/sub 12/, neo-C/sub 5/F/sub 12/, and to the cyclic c-C/sub 4/F/sub 8/ and c-C/sub 5/F/sub 10/ perfluoroalkanes has been studied using a time-of-flight mass spectrometer (TOFMS) and a high pressure electron swarm technique as well as the TOFMS results reported earlier on c-C/sub 4/F/sub 8/ and i-C/sub 4/F/sub 10/. Both long-lived parent anions (autodetachment lifetimes tau/sub a/ >10/sup -6/ s) and dissociative attachment fragment anions were observed for these molecules in the mass spectrometric study. The relative cross sections for negative ion formation and the tau/sub a/ of the long-lived parent anions were measured as a function of electron energy in the mass spectrometric study. The absolute total electron attachment rate constants as a function of the mean electron energy have been measured in the swarm study and used to calculate the total electron attachment cross sections as a function of electron energy. Both studies have shown a strong dependence of dissociative and nondissociative electron attachment processes on the structure of the molecules studied. For neo-C/sub 5/F/sub 12/, the predominant anion is the fragment C/sub 4/F/sup -//sub 9/. In contrast, for i-C/sub 4/F/sub 10/, i-C/sub 5/F/sub 12/, c-C/sub 4/F/sub 8/, and c-C/sub 5/F/sub 10/, the parent anions are stronger than any of the fragment anions. Energetic considerations have been employed to identify fragmentation mechanisms of the negative ion states (NISs) leading to the formation of the observed fragment anions and to deduce some thermochemical data.

• Research Organization: Atomic, Molecular, and High Voltage Physics Group, Health and Safety Research Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 5646039
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 83:2; ISSN JCPSA
• Country of Publication: United States
• Language: English

Related Subjects

640304* -- Atomic
Molecular &amp; Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
ANIONS
CHARGED PARTICLES
CHEMICAL REACTION KINETICS
COLLISIONS
CROSS SECTIONS
DISSOCIATION
ELECTRON ATTACHMENT
ELECTRON COLLISIONS
ELECTRON-MOLECULE COLLISIONS
FLUORINATED ALIPHATIC HYDROCARBONS
HALOGENATED ALIPHATIC HYDROCARBONS
IONS
KINETICS
MASS SPECTROSCOPY
MOLECULAR IONS
MOLECULE COLLISIONS
ORGANIC COMPOUNDS
ORGANIC FLUORINE COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
REACTION KINETICS
SPECTROSCOPY
TOTAL CROSS SECTIONS