Abstract We report the scanning tunneling microscope (STM) observation of the Li+ ion endohedral C60 on Cu(111), prepared by means of evaporation of a high-purity Li+@C60[PF6−] salt. The electronic state of Li+@C60 in the Li+@C60[PF6−] salt was also determined using photoemission and X-ray absorption spectroscopy, along with the density functional theory (DFT) calculations. In the salt, Li and PF6 had nearly single positive and negative charge, respectively; thus the C60 cage was practically neutral. The salt decomposed under ultra-high vacuum while heating at 400 °C. This allowed the selective deposition of Li+@C60 on Cu(111). Although secondary-ion mass spectroscopy of the deposited Li+@C60 film showed a decrease in the Li-content during evaporation, Li+@C60 was successfully identified using STM. The DFT calculations of Li+@C60 on Cu(111) suggested that the Li+ ion was singly charged and the location of the Li+ ion was displaced in an upward direction, which altered the local density of states in an upper section of C60, especially for LUMO+2. The calculated results were mostly in agreement with the bias-dependent STM and dI/dV images. However, an inconsistency was observed between the calculation and experiments in case of empty state imaging where tip-induced displacement of the Li+ ion may occur.

中文翻译：

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Li + @C 60 的电子结构：Li + @C 60 [PF 6 - ] 盐和 Cu(111) 上单个 Li + @C 60 分子的 STM 的光电子能谱

摘要 我们报告了通过蒸发高纯度 Li+@C60[PF6−] 盐制备的 Cu(111) 上 Li+ 离子内嵌 C60 的扫描隧道显微镜 (STM) 观察。Li+@C60[PF6-] 盐中 Li+@C60 的电子态也使用光发射和 X 射线吸收光谱以及密度泛函理论 (DFT) 计算确定。在盐中，Li和PF6分别带有几乎单一的正负电荷；因此，C60 笼实际上是中性的。盐在超高真空下在 400°C 加热时分解。这允许 Li+@C60 在 Cu(111) 上的选择性沉积。尽管沉积的 Li+@C60 薄膜的二次离子质谱显示在蒸发过程中锂含量降低，但使用 STM 成功识别了 Li+@C60。Li+@C60 在 Cu(111) 上的 DFT 计算表明 Li+ 离子是单电荷的，Li+ 离子的位置向上移动，这改变了 C60 上部的局部态密度，特别是对于LUMO+2。计算结果大多与偏差相关的 STM 和 dI/dV 图像一致。然而，在空态成像的情况下，计算和实验之间观察到不一致，其中可能发生锂离子的尖端诱导位移。