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Download fileComparative Study of the Adsorption of Thiol and Isocyanide Molecules on a Silver Surface by in Situ Surface-Enhanced Raman Scattering
journal contribution
posted on 26.08.2019, 18:36 authored by Jaewan Ahn, Shi Shi, Bonnie Vannatter, Dong QinWe
report an investigation of the adsorption of thiol and isocyanide
molecules on colloidal Ag nanocubes through surface-enhanced Raman
scattering (SERS). Specifically, we collect SERS spectra in situ at
different time points from a mixture of Ag nanocubes and ligand molecules
at a specific concentration. We demonstrate that 4-nitrothiophenol
could readily bind to the Ag surface through strong thiol–Ag
interaction. We also observe red shifts for the SERS peaks as the
concentration decreases, suggesting a change to the molecular orientation
relative to the surface. Likewise, 4-aminothiophenol also adsorbs
onto Ag quickly, but gives much weaker SERS signals relative to 4-nitrothiophenol
because the electron-donating amine group would retard the chemical
enhancement of SERS. Different from thiols, 1,4-phenylene diisocyanide
binds to Ag surface through a relatively weak, σ-donation bond.
With an increase in concentration, molecules tend to adsorb on the
nanocubes with the benzene ring tilting away from the surface. We
further investigate the competitive binding of thiol and isocyanide,
demonstrating the capability of thiol to inhibit the adsorption of
isocyanide when these two ligands are presented in a mixture.