A joint experimental and theoretical Raman study on the interactions of pyridine adsorbed on chemically pure Ag₁₈ clusters

Abstract

The interaction of pyridine–Ag has been a hot topic since the finding of surface‐enhanced Raman scattering; however, there is still challenge to accurately evaluate the interactions within nano‐systems. Here we have synthesized chemically pure Ag18 nanoclusters by a facile method based on laser ablation in liquid and conducted a joint experimental and theoretical Raman spectroscopic study for pyridine adsorbed on the specific‐sized Ag clusters. As a result, altered Raman feature for the pyridine‐Ag18 system in contrast to pure pyridine is observed shedding light on the charge‐transfer interactions between pyridine and Ag. Utilizing natural population analysis, we studied the charge distribution before and after pyridine adsorbed on the Ag18 cluster. Also, we calculated static polarizability components and isotropic polarizability of pyridine and the pyridine‐Ag18 complex and studied the donor‐acceptor orbital overlaps via natural bond orbital analysis, charge decomposition analysis, electron density difference analysis, and density of state analysis. Such a comprehensive and semiquantitative study provides firm evidence for the chemical mechanism in surface‐enhanced Raman scattering theory.

Recent advances in linear and nonlinear Raman spectroscopy. Part XIV

“…An et al [ 27 ] reported a joint experimental and theoretical Raman study of the interactions of pyridine adsorbed on chemically pure Ag 18 clusters. They found that a comprehensive and semiquantitative study provides firm evidence for the chemical enhancement mechanism in SERS theory.…”

Anionic Copper Clusters Reacting with NO: An Open-Shell Superatom Cu18–

“…In recent decades, extensive coinage metal clusters have been successfully synthesized via wet chemistry by proper ligand protection, including the aforementioned Au 20 , , Au 13 , and Au 18 nanoclusters . Meanwhile, a few ligand-protected Ag n nanoclusters of similar sizes have also been synthesized, such as Ag 18 , and Ag 19 nanoclusters . The extensive reports of coinage metal clusters allow their catalytic and optical properties to be revealed; however, the precise atomistic mechanism relating to activity and stability is still elusive and awaits full understanding.…”