Self-Assembled Monolayer Formation from Decaneselenol on Polycrystalline Gold As Characterized by Electrochemical Measurements, Quartz-Crystal Microbalance, XPS, and IR Spectroscopy

Abstract

Self-assembled monolayer (SAM) formation from decaneselenol on gold substrate surfaces was studied using electrochemical measurements, reflection-absorption Fourier transform infrared spectroscopy (FT-IRRAS), X-ray photoelectron spectroscopy (XPS), and quartz-crystal microbalance (QCM). The Au substrate modified with the SAMs showed clear IR absorption bands corresponding to the CH stretches while distinct photoemission peaks were observed at C 1s, Se 3d, and Se 3p core levels in its XPS spectrum. Using a quartz-crystal microbalance, the surface coverage by the SAM-forming molecule was determined to be 0.88 nmol cm -2 . Electrochemical impedance measurements revealed frequency-dependent capacitive behavior of the SAM, and the equivalent parameter was determined to be 6.1 × 10 -6 s φ Ω -1 cm -1 (φ ) 0.94). It also showed that the surface coverage of 99.8% can be attained, resulting in the suppression of a heterogeneous electron-transfer rate constant for a redox species dissolved in solution phase. The dielectric constant for the monolayer film was calculated to be 5.0, which was closer to that of alkanethiols than that reported for diphenyl diselenide. Decaneselenol was concluded to adsorb on Au surfaces to form stable monolayers such as alkanethiols.

Phase Transition of Octaneselenolate Self-assembled Monolayers on Au(111) Studied by Scanning Tunneling Microscopy

“…24,25 This can weaken the interactions between gold atoms in the first gold layers, so that a number of selenolate-gold complexes can easily be released from the gold surface as the surface coverage increases, resulting in the formation of disordered phases with larger fractions of VIs. Another possible reason for the unusual phase transition behavior of SAMs may be the solvent-mediated etching of SAM layers via oxidation of selenium headgroups, because the structural transition usually occurred during solution phase deposition.…”

“…23 Nakano et al demonstrated that decaneselenols on gold surfaces generated stable SAMs, as did alkanethiols. 24 The first molecular-scale STM observations of dodecanselenolate SAMs on Au(111) formed from didodecyl diselenide have a unique packing structure: these SAMs have a closely packed distorted hexagonal packing structure with a moiré pattern and a missing-row structure with a (√3 × 3√3)R30 o unit cell, unlike dodecanethiols.…”

Poly(hydroquinone)-coated electrode for immobilizing of 5′-amine functioned capture probe DNA and electrochemical response to DNA hybridization

“…A platinum wire and an Ag/AgCl (saturated KCl) were used to configure a three-electrode, electrochemical cell. The geometrical area of the Au electrode on the tip was 0.20 cm 2 and its roughness factor (R ¼ actual/geometric surface area) was determined to be 1.6 as previously reported [11].…”

Exchange versus intercalation of n-dodecanethiol monolayers on copper in the presence of n-dodecaneselenol and vice versa

“…and more recently their selenol counterparts [40][41][42][43][44][45][46][47][48][49][50][51][52][53][54], have been largely studied, and are attracting a large scientific interest which focuses on the understanding of the mechanisms taking place at the substrate/SAMs interface.…”