Fluorescence Spectroscopy on Molecules on Surfaces in the Limit of Low Coverages

本项目的目的是在极低覆盖率的限制下，从荧光（FL）和荧光激发光谱中获得介电表面上有机分子的信息。本项目利用FL光谱的高光谱分辨率和灵敏度，拟将实验甚至提高到单分子检测水平。实验将在定义明确的表面（NaCl/KCl(100)）上进行，同时通过表面科学技术（如低能电子衍射和扫描隧道显微镜）进行结构控制。据推测，这样的实验将提供以下方面的信息：(a)与电介质表面结合后修饰的分子的电子/几何状态，(b)不同吸附位置对光谱的影响以及是否可以通过选择性吸附（例如在特定缺陷位置）减少非均匀谱线加宽的问题，(c)分子在表面上的扩散、位置迁移和光化学过程的动力学，最后，(d)小分子聚集体，分子间耦合的量化及其在超辐射发射过程中的作用。

The aim of this project is to obtain information on organic molecules on dielectric surfaces from fluorescence (FL) and FL excitation spectroscopy in the limit of very low coverages. The project exploits the high spectral resolution and sensitivity of FL spectroscopy and intends to bring the experiments even to the single molecule detection level. The experiments will be performed on well-defined surfaces (NaCl/KCl(100)) with concomitant structural control by surface science techniques like low energy electron diffraction and scanning tunneling microscopy. It is supposed that such experiments will give information on the following aspects: (a) the electronic/geometric state of a molecule modified upon bonding to a dielectric surface, (b) the influence of different adsorption sites on the optical spectra and the question whether inhomogenous line broadening can be reduced by selective adsorption, e.g. at specific defect sites, (c) the kinetics of diffusion, site migration, and photochemical processes of a molecule on a surface, and finally, (d) for small molecular aggregates, a quantification of intermolecular coupling and its role for superradiant emission processes.