2018年7月1日

# Electronic structure of Li+@C60: Photoelectron spectroscopy of the Li+@C60[PF6−] salt and STM of the single Li+@C60 molecules on Cu(111)

Carbon
• ,
• Artem V. Kuklin
• ,
• Sho Sato
• ,
• Fumitaka Esaka
• ,
• Naoto Sumi
• ,
• Chunyang Zhang
• ,
• Masahiro Sasaki
• ,
• Eunsung Kwon
• ,
• Yukihiko Kasama
• ,
• Pavel V. Avramov
• ,
• Seiji Sakai

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DOI
10.1016/j.carbon.2018.02.106

Elsevier Ltd

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.

リンク情報
DOI
https://doi.org/10.1016/j.carbon.2018.02.106

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