Dynamics of charge transfer in self-assembled monomolecular films

该项目的主要目标是系统地研究分子电子学（ME）潜在构建块和组件中的飞秒电荷转移（CT）动力学，以获得最相关参数的定量数据-作为理论和分子设计的有价值输入-并更好地理解底层过程。为此，我们将应用基于同步加速器的共振俄歇电子能谱（RAES）结合芯孔时钟（CHC）方法的单分子组装的导电基板上的目标分子。上述方法依赖于将合适的RAES谱分解为与激发态的标准衰变和共振激发电子到衬底的CT相关的部分。它是无接触的，并使用已知的寿命内壳层的空缺，出现在俄歇过程中，作为一个内部的时间参考。由于靶分子的特殊设计，CT途径将通过尾基（腈等）的共振激发明确定义。连接到分子骨架上，而分子骨架又通过合适的头基连接到基底上。与项目的第一部分相比，（ZH 63/14-1），我们打算（i）通过选择特殊和限制性情况（如反向CT等）来测试RAES-CHC方法的适用范围，（ii）获得潜在分子导线的更广泛信息，（iii）阐明锚基团对CT动力学的贡献，如果可能的话，给出其最佳选择的建议，（iv）测试潜在的分子电子器件，例如无取代整流器（基于甘菊环的化合物）和光驱动开关（基于偶氮苯的化合物），以及（v）将RAES-CHC方法扩展到新系统。一个特别的注意力将放在分子轨道选择CT动力学的研究，可以解决在RAES-CHC方法的能量或对称性选择，如我们所示，在该项目的第一部分（ZH 63/14-1）。CT动力学实验将伴随静态CT测量（使用汞滴法），以获得目标系统和ME其他构件中CT现象的一致和全面的图像。

The main objective of the project is a systematic study of femtosecond charge transfer (CT) dynamics in potential building blocks and components of molecular electronics (ME) to get quantitative data on the most relevant parameters - as valuable input for theory and molecular design - and to achieve a better understanding of the underlying processes. To this end, we will apply synchrotron-based resonance Auger electron spectroscopy (RAES) in combination with the core hole clock (CHC) method to the monomolecular assembles of the target molecules on conductive substrates. The above approach relies on decomposition of the suitable RAES spectra into the parts related to the standard decay of the excited state and CT of the resonantly excited electron to the substrate. It is contact-free and uses the known lifetime of inner shell vacancy, appearing in the course of the Auger process, as an internal time reference. Due to the special design of the target molecules, the CT pathway will be unambiguously defined by the resonant excitation of the tail group (nitrile, etc.) attached to the molecular backbone which, in its turn, will be attached to the substrate by a suitable head group. As compared to the first part of the project (ZH 63/14-1), we intend (i) to test the applicability range of the RAES-CHC approach by selection of special and limiting cases such as reverse CT, etc, (ii) to get broader information on potential molecular wires, (iii) to clarify the contribution of the anchor group to CT dynamics and, if possible, to give recommendation for its optimal choice, (iv) to test the potential molecular electronics devices such as substitution-free rectifiers (azulene-based compounds) and light-driven switches (azobenzene-based compounds), and (v) to extend the RAES-CHC approach to new systems. A special attention will be put on the study of molecular-orbital-selective CT dynamics which can be addressed within the RAES-CHC approach by either energy or symmetry selection, as shown by us during the first part of the project (ZH 63/14-1). The CT dynamics experiments will be accompanied by the measurements of static CT (using the mercury drop method) to obtain a consistent and comprehensive picture of CT phenomena in the target systems and other building blocks of ME.