Computational insight into the origin of unexpected contrast in chiral markers as revealed by STM
Computational insight into the origin of unexpected contrast in chiral markers as revealed by STM
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STM 揭示的手性标记中意外对比的起源的计算洞察
DOI：
10.1039/c7nr07395j
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发表时间：
2018
期刊：
影响因子：
6.7
通讯作者：
Harvey Jeremy N.
中科院分区：
文献类型：
--
作者：
Sanz-Matias Ana;Ivasenko Oleksandr;Fang Yuan;De Feyter Steven;Tahara Kazukuni;Tobe Yoshito;Harvey Jeremy N.
内部取代基可以在二维自组装分子层中产生立体中心和（潜在地）通过扫描隧道显微镜（STM）识别的双重目的。我们通过计算研究了手性取代自组装有机薄膜的STM图像中鲜明对比变化的起源。模拟了含有-CH3和-OH基团的烷基衍生物的STM图像。密度泛函理论计算揭示了取代基区域中偏置依赖的对比度反转：在相关能量域中缺乏局部态密度导致模拟STM图像中的“黑点”，在增加偏置电压时变亮。
Internal substituents can serve the double purpose of generating stereogenic centers and (potentially) being identifiable with Scanning Tunneling Microscopy (STM) in 2D self-assembled molecular layers. We investigate computationally the origin of stark contrast variations in STM images of chirally substituted self-assembled organic films. STM images of alkyl derivatives with secondary –CH3 and –OH groups have been simulated. Density functional theory calculations reveal bias-dependent contrast reversals in the substituent regions: a lack of local density of states in the relevant energy regime results in ‘dark spots’ in the simulated STM images, which turn bright upon increasing the bias voltage.