Desorption of 4-Aminobenzenethiol Bound to a Gold Surface

Abstract

Desorption of 4-aminobenzenethiol (ABT) bound to a gold surface in bulk ethanol solution was studied by the measurement of the UV-absorption of the solution, from the points of both thermodynamics and kinetics. By eliminating the kinetic effects, we evaluated the equilibrium ratio of the adsorbed species with respect to the initial concentration of ABT in the solution. We found that the gold surface is fully covered by ABT above the bulk concentration of 0.5 mmol/dm3. By analyzing the kinetics of the surface reaction from adsorbed ABT to 4,4‘-diaminodiphenyl disulfide (DDD) and of the desorption of DDD, we deduced the rate of desorption of DDD from a fully covered gold surface. We found that the rate of desorption is extremely small, 1.6 × 10-5 min-1, due to rather strong binding of ABT to the native gold surface. These results suggest that there are two different processes for the desorption of DDD from a gold surface; one is from a native surface and the other is from a modified surface.

Current understanding of the structure, phase transitions and dynamics of self-assembled monolayers on two- and three-dimensional surfaces

“…In this method, the behaviour of thiol molecules on gold is studied during the desorption process [50]. Existence of dimer molecules on the surface has been reported by Mohri et al [51] which is in agreement with the SPR studies of Kajikawa et al [30]. Using a comprehensive TDS study, Noh et al [52] explained the existence of different adsorption sites and showed that dimerization plays a major role in SAM formation and desorption.…”

Surface-enhanced Raman scattering on tunable plasmonic nanoparticle substrates

“…[reference] are the estimated number of molecules in the enhanced and reference samples, respectively. The number of molecules in the sample was estimated by using the average number of nanoshells per spot, the surface area of the nanoshell, and the packing density of pMA on the nanoshell surface (35). This analysis assumes that the entire nanoshell surface area contributes to the Raman response and is a conservative estimate, essentially a lower bound, of the Raman enhancement.…”

“…Therefore, the measured Raman response should be proportional to ͉E shell ( o )͉ 2 ͉E Raman ( s )͉ 2 . This SERS optimization factor, ͉E shell ( o )͉ 2 ͉E Raman ( s )͉ 2 , is then calculated at each point on the nanoshell surface, assuming a monolayer of a molecule covering the surface of the nanoshell, and allowing for a coverage of 0.3 nm 2 per molecule (35).…”

Tuning the Optical Properties of Large Gold Nanoparticle Arrays

“…9 The adsorption of the tetrathiol resorcinarenes to the nanoparticles was expected to be robust, given the multivalent nature of the surfactants 10 and the very low rates of desorption of aryl monothiols from gold surfaces. 11 Aqueous solutions of citrate-stabilized 20-nm gold nanoparticles were treated with millimolar solutions of 1 in THF and extracted several times against toluene. Evaporation of the solvent resulted in a blue film at the solvent interface, which was directly transferred by horizontal (Langmuir-Schaefer) deposition onto a carbon-coated copper grid.…”