报告题目：Controlling functional properties and chemical reaction kinetics in low-dimensional systems
The electronic and optical properties of inorganic systems as well as the reaction behavior of organic molecules strongly depend on their dimensionality and/or that of their environment. Thus, controlling the dimensionality as well as the bond order in 0D, 1D and 2D systems at the sub-nanometer scale, their physical properties may qualitatively deviate from that of 3D bulk materials of the same chemical composition. For example, materials such a graphene exhibit excellent mechanical and thermal properties as well as high 2D electronic mobility. However, in their unmodified state these Dirac systems are lacking a finite electronic band gap, required for generating transistors. Graphene nanoribbons, representing 1D systems, on the other hand, allowed to overcome this limitation by using bottom up on-surface chemistry to control the ribbon latitude and thus, the band gap. In contrast, in other 2D systems such as Chalcogenides, finite band gaps are found. However, it is still a technical challenge here to grow large-scale systems with well-defined geometry for application in opto-electronic device. Our recent STM investigations on phosphenes and antimonene using UHV epitaxial growth revealed promising perspectives in these directions .
In the case or organic molecules, surfaces represent 1D or 2D spatial confinements for on-surface chemistry allowing a unique regioselective and kinetic control of chemical reaction schemes which otherwise cannot be done in liquid- or gas phase chemistry. In addition, surfaces can act catalytically and by reconstruction or faceting, and the confinement can display one- or zero dimensional character. Advanced LT-UHV Scanning probe techniques (LT-STM, nc-AFM) allow a detailed sub-molecularly resolved analysis of the reaction pathways, including intermediates, while complementary PES techniques (XPS/UPS) reveal the chemical reaction status of molecular systems [2, 3]. A novel type of nc-AFM tip developed in our group allows us to quantitatively characterize individual chemical bonds and even their bond-order with unprecedented precision .
Finally, the construction of high performance functional organic opto-electronic devices, following the biological self-organization approach can be done bottom up by combining nanotechnological methods with chemistry. Self-assembled pre-patterned interface layers, for example, allow to grow functional molecular layers in OFET/OSC structures in a well-controlled way, resulting, for example, in a significant increase in charge carrier mobility by more than one order of magnitude, without modifying the chemical systems making up the active OFET channel structures . Similarly, flexible organic photo responsive systems with ultrahigh detectivity can be generated .
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Harald Fuchs院士长期从事表面化学反应及纳米生物领域的研究工作并做出了重要贡献，是国际知名的表面化学及纳米生物学学者。哈拉尔德?福克斯院士是明斯特大学纳米技术研究中心的创始人，其研究领域主要集中在纳米科学和纳米技术，在扫描探针技术、自组装纳米材料、纳米生物体系等领域都取得了卓越的成就。迄今已在Nature,Science,Nature Nanotech,Nature Mat.,JACS,Angew.Chem.Int.Ed.,Adv.Mater.等重要期刊发表论文500余篇，拥有35个专利申请。