Structure and electronic structure of van der Waals interfaces at a Au(1 1 1) surface covered with a well-ordered molecular layer of n-alkanes

Hirotaka Mizushima, Harunobu Koike, Kenta Kuroda, Koichiro Yaji, Ayumi Harasawa, Yukiaki Ishida, Mitsuhiro Nakayama, Kazuhiko Mase, Kozo Mukai, Tatsuya Kitazawa, Takeshi Kondo, Jun Yoshinobu, Shik Shin, Kaname Kanai

Research output: Contribution to journalArticle

Abstract

The structure and electronic structure of a system comprising molecular layers of n-alkane adsorbed on Au(1 1 1) were investigated to understand the origin of the interfacial electric dipole layer. These alkane molecules are inert and thus van der Waals (vdW) interaction is the primary adsorptive force. Although these vdW interfaces are regarded as ideal physical adsorption systems unlikely to chemically interact with the metal surface, a large interfacial electric dipole layer over 1 eV is formed. It is important to elucidate the mechanism underlying the generation of such large dipole layers to understand the electrode interface in organic semiconductor devices. Thus, this paper elucidates the details of the vdW interface, in particular between tetratetracontane (TTC) and Au(1 1 1). First, the mechanism of growth of the TTC layer up to monolayer thickness was revealed using a low-energy electron-diffraction method. Second, the interface states were newly formed, as determined using angle-resolved photoelectron spectroscopy, X-ray photoemission spectroscopy, and near-edge absorption fine-structure spectroscopy. Our findings indicate, unexpectedly, that a relatively strong inter-orbital interaction governs this vdW interface, similar to a weak chemisorption system rather than a physisorption system.

Original languageEnglish
Article number147673
JournalApplied Surface Science
Volume535
DOIs
Publication statusPublished - 1 Jan 2021

Keywords

  • Electronic structure
  • Interfacial electric dipole layer
  • Organic/metal interface
  • Physisorption system
  • Van der Waals interface

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    Mizushima, H., Koike, H., Kuroda, K., Yaji, K., Harasawa, A., Ishida, Y., Nakayama, M., Mase, K., Mukai, K., Kitazawa, T., Kondo, T., Yoshinobu, J., Shin, S., & Kanai, K. (2021). Structure and electronic structure of van der Waals interfaces at a Au(1 1 1) surface covered with a well-ordered molecular layer of n-alkanes. Applied Surface Science, 535, [147673]. https://doi.org/10.1016/j.apsusc.2020.147673