AOT Bilayer Adsorption on Gold Surfaces: A Molecular Dynamics Study

Abstract

A molecular dynamics study was done to reveal the adsorption properties of sodium dioctyl sulfosuccinate (AOT) bilayers on gold Au(111) surfaces. Examining the rotational mobility of AOT molecules, we track that the correlation time of AOT molecules on the adsorbed layer is much higher. The data estimating the diffusive motion of AOT molecule show a substantially lower rate of diffusion (∼10 −10 cm 2 /s) in the adsorbed layers in comparison to other ones. The results show that an adsorbed layer is more rigid, whereas the outer layers undergo considerable lateral and vertical fluctuations.

Spiked gold nanotriangles: formation, characterization and applications in surface-enhanced Raman spectroscopy and plasmon-enhanced catalysis

“…We build on the MD simulations the AOT bilayer composed of 84 molecules adsorbed on Au(111) facets. 32,33 Aer addition of 50 AA molecules this system was optimized for 5000 steps. A 100 ns production run was carried out and the last 50 ns of production trajectories were used for data collection and further analysis.…”

“…Two simulations were carried out using GROMACS soware package and the CHARMM27 all-atom force eld protocols for the AOT surfactant, described by Abel et al 34 Note that the GOIP-CHARMM all atom force eld was applied to describe the gold surface, 35 already used by us previously. 32,33 The forceeld for AA molecules was retrieved with the CGenFF database server, 36 which generates the CHARMM force eld for small organic molecules. In two simulations, the SPC model 37 was used for water molecules.…”

“…45 Accompanying molecular dynamics (MD) simulations propose the adsorption of AOT micelles and bilayers on the {111} gold surface. 32,33 The excess of AOT molecules in the solution could be removed by centrifugation. 79% of the nanoplatelets (including hexagonal and triangular nanoprisms) are long-term stable AOT-coated AuNTs with an average edge length of 175 AE 17 nm.…”

“…Note, that the term nanotriangle is oen used for triangular nanoprisms, too. 48 Due to the existence of a more rigid adsorbed AOT bilayer with a lower rate of AOT diffusion ($10 À10 cm 2 s À1 calculated from MD simulations), 33 which act as stabilizer, the zeta potential is À59 mV. The absorption spectrum (Fig.…”

Gold Nanotriangles with Crumble Topping and their Influence on Catalysis and Surface‐Enhanced Raman Spectroscopy

“…In the resulting AuNT solution 79 % of the separated ultrathin nanoplatelets consist of triangular shaped nanoparticles with an edge length of 175±17 nm . The AuNTs, being composed of {111} facets on the top and bottom surfaces, are long‐term‐stabilized by an AOT‐bilayer as shown by MD simulations, transmission electron microscopy and EDX experiments . One special feature of the triangular nanoplatelets is a plasmon absorption peak in the near infrared range (NIR) range at ∼1200 nm, which is of relevance for in vivo imaging .…”