講座題目:物理學與信息技術學院 恒元物理學講座(第053期):Nanostructures and Interfaces investigated in Frequency and Time Domain
講座人:Prof. Arnulf Materny (Jacobs University Bremen, Germany)
講座時間:15:00
講座日期:2015-11-26
地點:長安校區(qū) 物理學與信息技術學院六層學術報告廳(致知樓3623-3624)
主辦單位:物理學與信息技術學院
講座內(nèi)容:Raman spectroscopy is a powerful technique, which yields information about molecules, which can be used for identifying molecular components as well as for the characterization of interactions of molecules with their environment. Unfortunately, Raman spectroscopy only yields relatively small signals, which makes it difficult to access small concentrations of molecules. A drastic increase of the scattering intensity can be observed when the molecules are adsorbed to surfaces of nano-structured coin-metal surfaces (e.g.silver or gold). Different mechanisms contribute to the surface-enhancement effect. However, surface-enhanced Raman scattering (SERS) is still not completely understood. While an enhancement of the electromagnetic wave of excitation and signal light can be nicely explained by plasmonic resonances and a “l(fā)ightning-rod effect”, the coupling of the electronic systems of the metal substrate and the molecules also plays a role. In our research, we try to access this “chemical” or “electronic enhancement” effect by performing experiments in the frequency and (femtosecond) time domain. In the presentation, techniques will be introduced, which allow for a reproducible investigation of SERS, as well as spectroscopic techniques, which help to access the effect on an ultrashort time scale.