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Adsorptive behavior of dimethylglyoxime on Au(111).

Langmuir : the ACS journal of surfaces and colloids (2011-10-18)
Jandee Kim, Sechul Kim, Choong Kyun Rhee
ABSTRACT

Dimethylglyoxime (DMG) adsorbed on Au(111) was investigated using electrochemical scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS). STM experiments revealed three different structures of adsorbed DMG at open circuit potential (~0.07 V versus Ag/AgCl): (2√3×2√3)R30°-α, (2√3×4√3)R30°-β, and (2√3×4√3)R30°-γ. The coverage of adsorbed DMG obtained using XPS was 0.33. A combination of structural and quantitative information identified the adsorbed DMG as an anionic tetramer, held together by intermolecular hydrogen bonding and arrayed in three ordered patterns. Domains of adsorbed DMG underwent phase transitions between the observed structures, most likely due to the influence of the STM tip. However, a significant correlation between the observed structures and the imaging conditions was not found. The ordered layers existed only at open circuit potential as evidenced by their disappearance when the potential was shifted to 0.2 or -0.15 V. The ordered layers were also removed by immersion in a solution of Ni(2+), implying that the adsorbed DMG was converted to a soluble dimer complex with the Ni(2+) ion. This particular observation is discussed in terms of the rigidity of the organic network.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Dimethylglyoxime, JIS special grade, ≥98.0%
Sigma-Aldrich
Dimethylglyoxime, ACS reagent, ≥99%
Sigma-Aldrich
Dimethylglyoxime, ≥97.0% (TLC)
Sigma-Aldrich
Dimethylglyoxime, puriss. p.a., ACS reagent, for the detection of Ni, ≥99.0% (TLC)