Hyperthermal Reactions of O+(4S3/2) with CD4 and CH4: Theory and Experiment
Abstract
Theoretical and experimental methods are applied to the study of the reaction dynamics in hyperthermal collisions of 0+(4S3/2) with methane. Measurements of the absolute reaction cross sections for the interaction of 0+ with CD4 and CH4 were obtained at collision energies in the range from near-thermal to approximately 15 eV, using the guided-ion beam (GIB) technique. Product recoil velocity distributions, using the GIB time-of-flight (TOF) methods, were determined for several product ions at selected collision energies. The main reaction channel, charge transfer, proceeds via large impact parameter collisions. A number of minor channels, involving more intimate collisions, were also detected. Ab initio electronic structure calculations have been performed with different levels of theory and basis sets, including high-level coupled-cluster calculations to determine the energies of reaction intermediates and transition states for reaction. Several reaction paths on both quartet and doublet electronic states of (OxCH4)+ are found, and these provide a reasonable qualitative interpretation of the experiments. Although most of the products can be produced via spin-allowed pathways, the appearance of CH3+ at low energies suggests that intersystem crossing plays some role.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 24, 2004
- Accession Number
- ADA441256
Entities
People
- Dale J. Levandier
- George C. Schatz
- Lipeng Sun
- Rainer A. Dressler
- Yu-hui Chiu
Organizations
- Air Force Research Laboratory