Cations-modified cluster model for density-functional theory simulation of potential dependent Raman scattering from surface complex/electrode systems

Abstract

Aiming to solve the problem of simulation of the potential dependent surface Raman spectra of anion containing surface complexes on electrodes, we developed a new simulation model by adding different cations (Li(+), Na(+), K(+), Rb(+) or Cs(+)) attached to the bottom layer of a large metallic cluster while the surface complex sits on the top layer.

Core–Shell Nanoparticle-Enhanced Raman Spectroscopy

“…The giant enhancement in SERS could be primarily attributed to the enhancement of the local EM field in the vicinity of the nanostructures and attributed to the enhanced efficiency of irradiation of the nanostructures mainly due to LSPR . In addition, five types of chemical effects may also contribute to the change of the relative and total Raman intensity, (1) ground states interaction, such as surface-complexation or chemisorption-induced increase of Raman polarizability, in the condition of far-away-from resonance; − (2) resonant or resonance-like Raman process, such as resonant Raman of free molecules, chemisorption-induced molecular resonance, or preresonance Raman processes; − (3) photon-driven electron-transfer from molecules to metal or the opposite; − (4) transient electron-enriched states due to extremely negatively applied potential in electrochemistry , or due to the donation of generated electrons to analytes; and (5) bias-voltage-enhanced Raman in molecular junctions. − It should be noted that chemical effect in SERS depends on the detailed electronic interaction in molecule–substrate systems. The general principles and the enhancement magnitudes should be carefully demonstrated and detected by rationally designed experiments.…”

SERS Spectra of Alizarin Anion–Agn (n = 2, 4, 14) Systems: TDDFT Calculation and Comparison with Experiment

“…Here only the Ag atoms facing close the CO groups of the AZ anion moiety in position 1, 9 were allowed to follow the optimization process. The rest of the cluster structure was kept frozen during the process, a procedure proposed by Ding et al 29 in the case of complexes with large silver clusters. Although the complex could not correspond to a global minimum, the reasonably fast convergence of the quantum chemical calculations and the absence of imaginary vibrational frequencies (see below) are strong indications that the structure corresponds or is close enough, to a local minimum and not to a saddle point of the potential energy surface (PES).…”

Toward a quantitative theoretical method for infrared and Raman spectroscopic studies on single-crystal electrode/liquid interfaces

“…First-principles computational methods based on cluster models with metal clusters to mimic the electrodes have been employed for calculating potential-dependent vibrational spectra of electroadsorbates. [15][16][17][18] However, the cluster models in EC simulations are usually too simplied to exactly consider important effects on electried single-crystal electrodes, such as the intermolecular interactions between electroadsorbates and periodic lattice structures. Therefore, slab models with periodic structures have been widely employed to study electroadsorption congurations and electrocatalytic mechanisms, especially for single-crystal or nanocrystal electrodes.…”