Abstract
Using several variants of the laser photoelectron attachment method, we have measured the energy-dependent yield for I− formation resulting from dissociative electron attachment (DEA) to CF3I molecules over the energy range 0.5–500 meV. One approach involved a static target gas (TG = 300 K) and pulsed electron production/anion extraction. In another approach, a collimated target was provided by a differentially pumped, seeded supersonic beam (10% CF3I in helium carrier gas, stagnation pressure 1 bar, nozzle temperature 300 K and 600 K). At the onsets for excitation of one and two quanta for the C–I stretching mode ν3, clear downward cusps are detected. With reference to the recommended thermal DEA rate coefficient kA(Te = TG = 300 K) = 1.9 × 10−7 cm3 s−1, a new highly resolved absolute cross section for I− formation has been determined. Our experimental results are well reproduced by a cross section calculated in the framework of the resonance R-matrix theory. The input for the theory includes the known energetic and structural parameters of the neutral molecule and its anion and adopts a revised vertical attachment energy and a surface amplitude chosen to reproduce the thermal DEA rate coefficient. The theory is also applied to predict absolute cross sections for vibrational excitation of the C–I stretching mode ν3. Using our experimental and theoretical DEA cross sections we derive rate coefficients for Rydberg electron transfer (RET) and the dependence of the rate coefficients for free electron attachment of a Maxwellian electron ensemble on the mean electron energy from 0.002 to 2 eV at the constant gas temperature TG = 300 K; in both cases good agreement is observed with direct RET and swarm measurements.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
More From: Journal of Physics B: Atomic, Molecular and Optical Physics
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.