A Two-Dimensional Model for Collisional Energy Transfer in Bimolecular Ion-Molecule Dynamics
Abstract
Guided ion beam kinetic energy thresholds in the ion-molecule reactions M(+)+H2 yields MH(+)+H where M(+) is a closed-shell atomic ion B(+), Al(+), or Ga(+), were found to exceed by 0.4 to c.a. 5 ev the thermodynamic energy requirements (or the theoretically computed barrier heights) for these reactions. In addition, the formation of MD(+) occurs at a significantly lower threshold than MH(+) when M(+) reacts with HD. Moreover, the measured reaction cross-sections for the production of MH(+) or MD(+) product ions are very small (10(exp -17) to 10( exp -20)sq cm) being largest for B(+) and smallest for Ga(+) . A previous paper from this group proposed that collisional-to-internal energy transfer is the rate-limiting step for this class of reactions. It also suggested, based on a dynamical resonance picture, that collisions occurring at or near C2v symmetry are more effective than other collisions even though C2v geometries provide no lower potential energy barriers than others.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 22, 1994
- Accession Number
- ADA278913
Entities
People
- Jack Simons
- Monique R. Chacon-taylor
Organizations
- University of Utah