Electron Stimulated O(-) Desorption from O2 Condensed on a Rare-Gas Film: Evidence for an Indirect 'Bounce' Trajectory
Abstract
The electron-stimulated O(-) dissociation of O2 gas is well understood. In the energy range from 4 to 10 eV, O(-) ions are produced by dissociative attachment (DA) via the transient O2(-)(2Pi(u)) state. This same DA process has been identified in electron-stimulated desorption (ESD) or O(-) ions from O2. However, electron-energy-dependence curve of the O(-) yield is quite different from that for gaseous O2. The gas-phase curve rises slowly at the threshold and has a symmetric bell shape, while the condensed-phase curve rises sharply at the threshold and has an asymmetric triangular shape. Furthermore, the threshold energy of the condensed-phase curve depends on the rare-gas substrate. In this note, we offer an explanation for the threshold changes and suggest a trajectory for the O(-) ion desorption via the O2(-)(2 Pi(u)) intermediate state. We shall explain the different energy dependence elsewhere. (aw)
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1989
- Accession Number
- ADA216725
Entities
People
- David E. Ramaker
- H. Sambe
Organizations
- George Washington University