Single-Molecule Rotational Switch on a Dangling Bond Dimer Bearing
Single-Molecule Rotational Switch on a Dangling Bond Dimer Bearing
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DOI：
10.1021/acsnano.6b03590
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发表时间：
2016-09-01
期刊：
影响因子：
17.1
通讯作者：
Saeys, Mark
中科院分区：
文献类型：
--
作者：
Godlewski, Szymon;Kawai, Hiroyo;Saeys, Mark
构建原子级电路和分子机器的关键挑战之一是通过控制分子的线性或旋转运动来设计分子转子和开关，同时保持其固有的电子特性。在这里，我们展示了在氢钝化的Ge(001):H表面上，吸附在悬空键二聚体上的三乙烯分子的连续旋转开关和受控的一步一步的单开关。当分子与悬空键二聚体之间的共价键被控制地断裂时，分子开关在表面组装，并且分子通过远程范德华相互作用附着在二聚体上。通过扫描隧道显微镜/光谱（STM/STS）测量、密度泛函理论计算和先进的STM图像计算证实，在这种构型下，分子保留了其固有的电子性质。当电子隧穿分子的最低未占据分子轨道状态时，分子的连续开关是由振动激发引起的。切换路径是在悬空键二聚体枢轴上滑动和旋转运动的组合。通过仔细选择STM条件，还可以实现对离散的单个开关事件的控制。结合以原子精度制造悬空键二聚体的能力，这种受控的旋转分子开关有望成为更复杂的表面原子尺度设备的关键组成部分。
One of the key challenges in the construction of atomic-scale circuits and molecular machines is to design molecular rotors and switches by controlling the linear or rotational movement of a molecule while preserving its intrinsic electronic properties. Here, we demonstrate both the continuous rotational switching and the controlled step-by-step single switching of a trinaphthylene molecule adsorbed on a dangling bond dimer created on a hydrogen-passivated Ge(001):H surface. The molecular switch is on-surface assembled when the covalent bonds between the molecule and the dangling bond dimer are controllably broken, and the molecule is attached to the dimer by long-range van der Waals interactions. In this configuration, the molecule retains its intrinsic electronic properties, as confirmed by combined scanning tunneling microscopy/spectroscopy (STM/STS) measurements, density functional theory calculations, and advanced STM image calculations. Continuous switching of the molecule is initiated by vibronic excitations when the electrons are tunneling through the lowest unoccupied molecular orbital state of the molecule. The switching path is a combination of a sliding and rotation motion over the dangling bond dimer pivot. By carefully selecting the STM conditions, control over discrete single switching events is also achieved. Combined with the ability to create dangling bond dimers with atomic precision, the controlled rotational molecular switch is expected to be a crucial building block for more complex surface atomic-scale devices.