Gas-Surface Interactions Near Dissociation Threshold
Abstract
The main thrust of our program was directed towards the study collision-induced dissociation (CID) of hyperthermal molecules on insulators (MgO), semiconductors (GaAs) and metals (Ag). Supersonic beams of nitroso compounds entered the UHV chamber with kinetic energies variable between 0.5 and 7 eV. NO products were detected state-selectively using two-frequency laser ionization. CTD yields were measured as a function of surface temperature and incident kinetic energy, and complete energy deposition in the NO product was determined in each case. CID yields rise sharply with incident kinetic energy, with non-vanishing values even slightly below dissociation threshold at high surface temperature. The yield depends on the stiffness of the surface. The NO distributions are similar to those obtained in the gas-phase unimolecular decomposition of these molecules and indicate a broad distribution of internal energies. In the newest phase of this program, the photodissociation of C1NO adsorbed on a rough MgO surface is studied at 365 nm. The NO state distributions differ greatly from those obtained in gas-phase photodissociation and suggest that C1NO aggregates as islands on the surface and the NO and Cl undergo multiple collisions before desorption. Surface, Collision-Induced Dissociation, Photodissociation.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 26, 1992
- Accession Number
- ADA250205
Entities
People
- Curt Wittig
- Hanna Reisler
Organizations
- University of Southern California