The pressure-dependent C-N stretching mode, nu(C-N), for thiocyanate ions adsorbed at the silver nanoparticles-aqueous interface is examined in situ by surface-enhanced Raman spectroscopy (SERS) via a commonly used diamond anvil cell in the experimental pressures range from 31 MPa to 943 MPa. The spectroscopic measurements show that three different geometries are adopted by thiocyanate ions adsorption simultaneously at high pressure. The stretching mode nu(C-N) of S-bound around 2120 cm(-1) exists throughout the whole pressure range and the intensity of nu(C-N) of N-bound around 2070 cm(-1) increased with the pressure. The nu(C-N) of bridge-bound coexist with the stretching mode nu(C-N) of S-bound and N-bound in the form of weak peaks around 2220 cm(-1) at the pressures range from 627 MPa to 943 MPa. Current results demonstrate that high pressure promotes the N-bound and bridge-bound adsorption of thiocyanate ions on the surface of silver nanoparticles.

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