Atypical charge redistribution over a charge-transfer monolayer on a metal
Atypical charge redistribution over a charge-transfer monolayer on a metal
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DOI：
10.1088/1367-2630/15/8/083048
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发表时间：
2013-08
影响因子：
3.3
通讯作者：
T. Umbach;I. Fernández-Torrente;Michael Ruby;F. Schulz;C. Lotze;R. Rurali;M. Persson;J. Pascual;K. Franke
中科院分区：
文献类型：
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作者：
T. Umbach;I. Fernández-Torrente;Michael Ruby;F. Schulz;C. Lotze;R. Rurali;M. Persson;J. Pascual;K. Franke
我们报道了钠（Na）和四氰基醌二甲烷（TCNQ）在Au（111）表面上的高度有序单层膜中的非典型电荷分布。在电荷转移层纳入钠原子捐赠其3s电子的TCNQ受体的最低未占轨道。在扫描隧道光谱中观察到这样的TCNQ阴离子的指纹作为近藤效应的零偏置峰特征。近藤共振的空间图令人惊讶地显示，它似乎在Na位点上最强烈。支持密度泛函理论模拟，我们解释这种奇特的电荷分布模式起源于单占据分子轨道超出分子骨架的延伸，并掩盖了钠阳离子。我们进一步建议，这种变形的分子轨道是一个后果的极性Na-TCNQ层的静电势景观。
We report an atypical charge distribution in a highly ordered monolayer of sodium (Na) and tetracyanoquinodimethane (TCNQ) on a Au(111) surface. Na atoms incorporated in the charge-transfer layer donate their 3s electron to the lowest unoccupied orbital of the TCNQ acceptor. A fingerprint of such a TCNQ anion is observed in scanning tunneling spectroscopy as a zero-bias peak characteristic of the Kondo effect. Spatial maps of the Kondo resonance surprisingly reveal that it appears most intense on top of the Na sites. Supported by density functional theory simulations, we interpret this peculiar charge distribution pattern as originating from the extension of the singly occupied molecular orbital beyond the molecular backbone, and cloaking the Na cations. We further suggest that this deformation of molecular orbitals is a consequence of the electrostatic potential landscape of the polar Na–TCNQ layer.