Pan Yi, Kanisawa Kiyoshi, Ishikawa Naoto, Fölsch Stefan
Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5-7, 10117 Berlin, Germany.
J Phys Condens Matter. 2017 Sep 13;29(36):364001. doi: 10.1088/1361-648X/aa7dc4. Epub 2017 Jul 5.
A scanning tunnelling microscope (STM) operated at 5 K was used to study dysprosium biphthalocyanine (DyPc) molecules adsorbed on the inert III-V semiconductor surface InAs(1 1 1)A. Orbital imaging and scanning tunnelling spectroscopy measurements reveal that the molecular electronic structure remains largely unperturbed, indicating a weak molecule-surface binding. The molecule adsorbs at the In vacancy site of the (2 × 2)-reconstructed surface and is highly sensitive to current-induced excitations leading to random rotational fluctuations. Owing to the weak surface binding, individual molecules can be precisely repositioned and arranged by the STM tip via attractive tip-molecule interaction. In this way, DyPc dimers of well-defined internal structure can be assembled which exist in two conformations of equivalent appearance. A binary switching between these two conformers can be induced by injecting electrons into one of the two molecules. The conformational change of the dimer proceeds via a concerted molecular rotation and minor lateral displacement. The synchronised switching observed here is attributed to steric interactions between the two molecules constituting the dimer.
一台在5K温度下运行的扫描隧道显微镜（STM）被用于研究吸附在惰性III-V族半导体表面InAs(1 1 1)A上的镝双酞菁（DyPc）分子。轨道成像和扫描隧道光谱测量表明，分子的电子结构基本未受干扰，这表明分子与表面的结合较弱。该分子吸附在(2×2)重构表面的In空位处，并对电流诱导的激发高度敏感，从而导致随机旋转波动。由于表面结合较弱，单个分子可以通过STM针尖与分子之间的吸引相互作用被精确地重新定位和排列。通过这种方式，可以组装出具有明确内部结构的DyPc二聚体，其存在两种外观等效的构象。向两个分子中的一个注入电子可以诱导这两种构象体之间的二元切换。二聚体的构象变化通过协同的分子旋转和微小的横向位移进行。这里观察到的同步切换归因于构成二聚体的两个分子之间的空间相互作用。
