%0 Journal Article
%T Adsorption of rhodamine 6G and choline on gold electrodes: a molecular dynamics study.
%A Wang X
%A Ham S
%A Zhou W
%A Qiao R
%A Wang X
%A Ham S
%A Zhou W
%A Qiao R
%J Nanotechnology
%V 0
%N 0
%D Oct 2022 4
%M 36195059
%F 3.953
%R 10.1088/1361-6528/ac973b
%X The adsorption of analyte molecules on nano-optoelectrodes (e.g., a combined nanoantenna and nanoelectrode device) significantly affects the signal characteristics in Surface-Enhanced Raman Scattering (SERS) measurements. Understanding how different molecules adsorb on electrodes and their modulation of electrical potential help better interpret SERS measurements. This work investigates the adsorption of prototypical analyte molecules, Rhodamine 6G and choline, on gold electrodes with negative, neutral, and positive surface charges using molecular dynamics simulations. We show that both molecules can readily adsorb on gold surfaces at all surface charge densities considered here. Nevertheless, the configurations of adsorbed molecules can differ for different surface charge densities, and adsorption can also change a molecule's conformation. Rhodamine 6G molecules adsorb more strongly than choline molecules, and the adsorption of both molecules is affected by electrode charge in 0.25 M NaCl solutions. The mechanisms of these observations are elucidated, and their implications for SERS measurements are discussed.