An Yang, Tang Xiangqian, Wang Wenyu, Hao Dong, Zhao Xinjia, Wang Muyu, Ye Xia, Shan Xinyan, Lu Xinghua
Beijing National Laboratory for Condensed-Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.
School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100190, China.
ACS Nano. 2022 Nov 22;16(11):18592-18600. doi: 10.1021/acsnano.2c07081. Epub 2022 Sep 6.
A controlled chemical reaction on a specific bond in a single molecule is an inevitable step toward atomic engineering and fabrication. Here, we explored the debromination of a single 9,10-dibromoanthracene (DBA) molecule on a surface as stimulated by the voltage pulse through the tip of a scanning tunneling microscope (STM). A voltage threshold of about 2.2 V is obtained, and the nature of single-electron process is revealed. The spatially resolved debromination yield is obtained as a function of the pulse magnitude, which presents strong asymmetry for the two C-Br bonds. The optimal stimulation parameters including the pulse magnitude and the tip locations are suggested. The distinct dynamics in dissociation of the two bonds are illustrated by their energy diagrams and recoil paths, as derived by the first-principles density functional theory (DFT) calculation. The influence of the local electric field due to the STM tip on the dissociation of the C-Br bond has also been discussed. The study presents detailed practice for the controlled debromination in a single DBA molecule, which may lead to automated atomic engineering and fabrication of artificial nanostructures in the future.
对单个分子中的特定化学键进行可控化学反应是迈向原子工程与制造的必经步骤。在此，我们探究了通过扫描隧道显微镜（STM）针尖施加电压脉冲刺激时，单个9,10-二溴蒽（DBA）分子在表面上的脱溴反应。获得了约2.2 V的电压阈值，并揭示了单电子过程的本质。得到了空间分辨的脱溴产率与脉冲幅度的函数关系，该关系对于两个C-Br键呈现出强烈的不对称性。提出了包括脉冲幅度和针尖位置在内的最佳刺激参数。通过第一性原理密度泛函理论（DFT）计算得出的能量图和反冲路径，说明了两个化学键解离过程中不同的动力学。还讨论了STM针尖产生的局部电场对C-Br键解离的影响。该研究展示了单个DBA分子可控脱溴的详细实践，这可能在未来促成人工纳米结构的自动化原子工程与制造。
