双共振和频光谱分析自组装单分子层/铂界面的电子结构  

Analysis of electronic structure of self-assembled monolayer and Pt interface by doubly resonant sum frequency generation spectroscopy

作　　者：王悦 何玉韩 刘晓琳 宋前通 王朝晖 WANG Yue;HE Yuhan;LIU Xiaolin;SONG Qiantong;WANG Zhaohui(Key Laboratory of Spectrochemical Analysis&Instrumentation,Ministry of Education,College of Chemistry and Chemical Engineering,Xiamen University,Xiamen 361005,China)

机构地区：[1]厦门大学化学化工学院,谱学分析与仪器教育部重点实验室,福建厦门361005

出　　处：《厦门大学学报（自然科学版）》2024年第3期526-531,549,共7页Journal of Xiamen University：Natural Science

基　　金：国家自然科学基金(22072121,21327901)。

摘　　要：[目的]界面电子结构对于物理和化学过程具有重要的影响,发展界面电子结构的表征方法具有重要意义.[方法]以Pt表面自组装单分子层(SAM)为模型体系,根据和频(SFG)光谱强度随入射光波长的变化,研究SAM对Pt基底电子结构的影响.[结果]研究发现,对巯基苯甲腈分子自组装于Pt基底表面时,基底的SFG响应显著增强.对巯基苯甲腈分子通过巯基与Pt表面相互作用,改变了界面电子结构,形成了SAM/Pt电荷转移态,在510~620 nm波段出现了新的吸收带,从而产生双共振SFG效应使基底的SFG响应显著增强.[结论]具有界面选择性的SFG光谱可以有效分析金属界面的电荷转移态,是研究界面电子结构的有力工具.[Objective]The charge transfer(CT)process is a crucial step in important chemical reactions such as photovoltaic devices,photocatalytic reactions,and industrial corrosion prevention.The interfacial electronic structure has significant impacts on the CT process,and therefore,developing methods to characterize this structure is of great importance.Sum frequency generation(SFG),known for its intrinsically surface selectivity,is a powerful tool to study interfacial electronic structure.In this study,self-assembled monolayers(SAM)on Pt film were used as a model system.By analyzing the wavelength-dependent SFG spectra,the influence of SAM-metal interactions on the electronic structure of the Pt surface was investigated.[Methods]SFG is a second order nonlinear process.In broadband SFG,a femtosecond infrared(IR)beam and a narrowband picosecond visible(Vis)beam are spatially and temporally overlapped on the sample surface,and the output SFG signal radiates in the phase matching direction.When the IR frequency matches the vibrational modes at the interface,SFG signal will be resonantly enhanced.Additionally,when the Vis or SFG resonate with the electronic transitions,the doubly resonant(DR)condition significantly enhances the SFG signal.By scanning the IR and Vis wavelength,interfacial specific vibrational and electronic spectra can be obtained,respectively.The wavelength-dependent SFG spectra were recorded using a spectrograph equipped with a CCD array detector in the PPP polarization combination(P-SFG,P-Vis and P-IR).The SAM/Pt samples were prepared by soaking the e-beam deposited Pt(100 nm thickness on silicon substrates)in 0.1 mmol/L solutions of p-mercaptobenzonitrile(p-MBN)or 4-isothiocyanato-benzonitril(ITC-BN)in ethanol for 24 h,followed by thorough washing before SFG measurements.[Results]In the SFG spectra of the SAM/Pt samples,the nonresonant response of the Pt surface(NR,broadband feature in the SFG spectra corresponding to the electronic response of the metal surface and roughly representing the incident IR sp

关 键 词：双共振和频光谱 自组装单分子层 界面电子结构 

分 类 号：O657.38[理学—分析化学]