A Density Functional Theoretical Study on the Charge‐Transfer Enhancement in Surface‐Enhanced Raman Scattering. Issue 24 (20th November 2018)

• Record Type: Journal Article
• Authors: Gao, Shu‐Ting; Xiang, Shi‐Qin; Jiang, Yimin; Zhao, Liu‐Bin
• Is Part Of: Chemphyschem. Volume 19:Issue 24(2018)
• Page Start: 3401
• Page End: 3409
• Publication Date: 2018-11-20
• Subjects: charge transfer -- density functional theory -- functional groups -- surface-enhanced Raman scattering -- thiophenol; Chemistry, Physical and theoretical -- Periodicals; 541.05
• DOI: 10.1002/cphc.201800812
• Languages: English
• ISSNs: 1439-4235

Abstract

Abstract: The chemical enhancement due to ground‐state charge transfer (GSCT) and photon‐driven charge transfer (PDCT) in surface‐enhanced Raman scattering (SERS) has been investigated by density functional theory. Para‐substituted thiophenol derivatives adsorbed on silver and gold surfaces are selected as model systems to evaluate the chemical enhancement factor. By changing the functional groups on thiophenol, we are allowed to modulate the chemical interactions between the thiophenol and the metal cluster in both ground state and charge transfer excited state. Both off‐resonance and pre‐resonance SERS spectra are simulated to calculate the chemical enhancement factors. The GSCT enhancement factor, EFGSCT, shows a roughly linear relationship to ( ω TP / ω M‐TP ) 4, where ω TP denotes the HOMO‐LUMO gap of free molecule, and ω M‐TP denotes the energy difference between the HOMO of the molecule and the LUMO of the metal. The PDCT enhancement factor, EFPDCT, is governed by the energy difference between the incident light energy and the excitation energy to the CT excited state. EFPDCT first increases and then decreases with the increase of incident light energy. Abstract : Chemical enhancement due to ground‐state charge transfer (GSCT) and photon‐driven charge transfer (PDCT) in surface‐enhanced Raman scattering from a series of para‐substituted thiophenol derivatives adsorbed on silver and gold surfaces is investigated by density functional theory.