Electronic states of alkanethiolate self-assembled monolayers on Au(111) studied by two-photon photoemission spectroscopy

Naoyuki Hirata, Masahiro Shibuta, Ryo Matsui, Atsushi Nakajima

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

Two-photon photoemission (2PPE) spectroscopy has been employed to probe the electronic states of n-alkanethiolate self-assembled monolayers (SAMs) on an Au(111) substrate fabricated in a wet chemical process. Electronic states newly formed in the SAM formation were observed below and above the Fermi level (E F) for various alkyl chain lengths of C12-, C18-, and C22-SAMs. At 3.5-3.7 eV above E F, an unoccupied state originating from a bond between gold and sulfur atoms appears, a state that shows little dispersion with parallel to the surface. The peak position of the unoccupied state depends on the substrate temperature, and it was stabilized with increasing temperature; E F +3.7 eV at 85 K and E F +3.5 eV at 330 K for C18-SAM. The stabilization of the state is attributed to the increase of intermolecular interaction at sulfur atoms with their neighboring S atoms, which is caused by a change in the tilt angle of the alkyl chains in the SAM: on increasing the temperature, the interaction between S atoms in the SAM is promoted by the more upright alkyl chains.

Original languageEnglish
Pages (from-to)13623-13628
Number of pages6
JournalJournal of Physical Chemistry C
Volume116
Issue number25
DOIs
Publication statusPublished - 2012 Jun 28

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Electronic states
Self assembled monolayers
Photoelectron spectroscopy
photoelectric emission
Photons
photons
electronics
spectroscopy
atoms
Atoms
sulfur
Sulfur
temperature
stabilization
interactions
Substrates
gold
Fermi level
Chain length
Gold

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Electronic, Optical and Magnetic Materials
  • Surfaces, Coatings and Films
  • Energy(all)

Cite this

Electronic states of alkanethiolate self-assembled monolayers on Au(111) studied by two-photon photoemission spectroscopy. / Hirata, Naoyuki; Shibuta, Masahiro; Matsui, Ryo; Nakajima, Atsushi.

In: Journal of Physical Chemistry C, Vol. 116, No. 25, 28.06.2012, p. 13623-13628.

Research output: Contribution to journalArticle

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