Adsorption of Chlorine on Clean and on Oxygen Pre-Exposed Al(III)
Abstract
The adsorption of Cl2 (chlorine) on clean and on O2 (oxygen) pre- exposed Al(111) (aluminum) has been studied using Auger and electron energy loss spectroscopies, low energy electron diffraction, temperature programmed desorption and work function measurement. Near room temperature chlorine forms a disordered layer in a two-step process consisting of adsorption at surface sites, dominating at low exposure, followed by population of subsurface sites at higher exposure. Surface adsorption is characterized by a sticking coefficient of about 0.1, an increase in work function of about 1 eV and a desorption peak at about 200 C. The subsurface phase exhibits a smaller sticking coefficient and work function change and no distinct desorption peak. Pre-absorbed 0 blocks formation of subsurface species but not those formed in the initial adsorption step. Cl2 does not displace pre-absorbed 0, but 02 displaces some subsurface Cl. Chlorination is found to occur inhomogeneously rather than uniformly in a layer- by-layer mode. Keywords: Corrosion of aluminum, Halogens, Oxidation.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 1988
- Accession Number
- ADA198005
Entities
People
- A. S. Glass
- V. M. Bermudes
Organizations
- United States Naval Research Laboratory