物理学与信息技术学院 恒元物理学讲座（第053期）：Nanostructures and Interfaces investigated in Frequency and Time Domain

讲座内容：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 “lightning-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.