X-ray scattering study of Tl adlayers on the Au(111) electrode in alkaline solutions. Metal monolayer, OH[sup [minus]] coadsorption, and oxide formation
- Brookhaven National Lab., Upton, NY (United States)
The structure of electrodeposited Tl adlayers on Au(111) in 0.1 M NaOH has been investigated using surface X-ray scattering. Incommensurate, hexagonal Tl structures exist over a wide potential region positive of bulk deposition. In the potential region between -0.66 and -0.38 V (versus Ag/AgCl), the Tl monolayer is rotated from the substrate axes by 5.2[degree]-6.2[degrees] and is closely packed with a Tl-Tl separation ranging from 3.34 to 3.43 [angstrom]. Between [minus]0.36 and -0.18 V, an incommensurate, aligned-hexagonal phase is observed in which the Tl-Tl spacing increases with increasing potential from 3.88 to 4.10 [angstrom]. The first-order transformation between these two phases at -0.37 V involves the coadsorption of OH[sup [minus]]. For the aligned-hexagonal phase the electrosorption valence is larger than unity, which indicates that partially-charged hydroxyl species are coadsorbed. The coadsorption of OH[sup [minus]] facilitates the existence of this unusual low-coverage, incommensurate Tl phase. At more positive potentials, the hexagonal adlayer lattice continuously rotates away from the substrate axes. At E > -0.04 V the adlayer appears disordered, and a two Tl atom thick Tl[sub 2]O adlayer forms. 26 refs., 12 figs., 1 tab.
- DOE Contract Number:
- AC02-76CH00016
- OSTI ID:
- 7126053
- Journal Information:
- Journal of Physical Chemistry; (United States), Vol. 98:29; ISSN 0022-3654
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
99 GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE
THALLIUM
ADSORPTION
ELECTRODEPOSITION
ELECTRODES
GOLD
MATHEMATICAL MODELS
PHASE STUDIES
SCATTERING
SODIUM HYDROXIDES
VOLTAMETRY
X RADIATION
ALKALI METAL COMPOUNDS
DEPOSITION
ELECTROLYSIS
ELECTROMAGNETIC RADIATION
ELEMENTS
HYDROGEN COMPOUNDS
HYDROXIDES
IONIZING RADIATIONS
LYSIS
METALS
OXYGEN COMPOUNDS
RADIATIONS
SODIUM COMPOUNDS
SORPTION
SURFACE COATING
TRANSITION ELEMENTS
400400* - Electrochemistry
400102 - Chemical & Spectral Procedures
990200 - Mathematics & Computers