Electronic structure of Li+@ C60: Photoelectron spectroscopy of the Li+@ C60 [PF6−] salt and STM of the single Li+@ C60 molecules on Cu (111)
URI (for links/citations):https://www.sciencedirect.com/science/article/pii/S0008622318302422
Artem, V Kuklin
Pavel, V Avramov
Journal Quartile in Scopus:Q1
Journal Quartile in Web of Science:Q1
Bibliographic Citation:Yoichi, Yamada. Electronic structure of Li+@ C60: Photoelectron spectroscopy of the Li+@ C60 [PF6−] salt and STM of the single Li+@ C60 molecules on Cu (111) [Текст] / Yamada Yoichi, V Kuklin Artem, Sato Sho, Esaka Fumitaka, Sumi Naoto, Zhang Chunyang, Sasaki Masahiro, Kwon Eunsung, Kasama Yukihiko, V Avramov Pavel, Sakai Seiji // Carbon. — 2018. — Т. 133. — С. 23-30
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.