The role of electronic mechanisms in surface erosion and glow phenomena
- Haglund, Richard F., Jr.
- Jun 1, 1987.
- Physical Description:
- 1 electronic document
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- Experimental studies of desorption induced by electronic transitions (DIET) are described. Such studies are producing an increasingly complete picture of the dynamical pathways through which incident electronic energy is absorbed and rechanneled to produce macroscopic erosion and glow. These mechanistic studies can determine rate constants for erosion and glow processes in model materials and provide valuable guidance in materials selection and development. Extensive experiments with electron, photon, and heavy particle irradiation of alkali halides and other simple model materials have produced evidence showing that: (1) surface erosion, consisting primarily in the ejection or desorption of ground-state neutral atoms, occurs with large efficiencies for all irradiated species; (2) surface glow, resulting from the radiative decay of desorbed atoms, likewise occurs for all irradiating species; (3) the typical mechanism for ground-state neutral desorption is exciton formation, followed by relaxation to a permanent, mobile electronic defect which is the precursor to bond-breaking in the surface or near-surface bulk of the material; and (4) the mechanisms for excited atom formation may include curve crossing in atomic collisions, interactions with surface defect or impurity states, or defect diffusion.
- Other Subject(s):
- NASA Technical Reports Server (NTRS) Collection.
- Document ID: 19870016748.
Accession ID: 87N26181.
Jet Propulsion Lab., Proceedings of the NASA Workshop on Atomic Oxygen Effects; p 63-74.
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