Adsorbed structures of 4,4′-bipyridine on Cu(111) in acid studied by STM and IR

Yu Xia Diao, Mei Juan Han, Li Jun Wan, Kingo Itaya, Taro Uchida, Hiroto Miyake, Akira Yamakata, Masatoshi Osawa

Research output: Contribution to journalArticlepeer-review

40 Citations (Scopus)


The adsorption of 4,4′-bipyridine (BiPy) on Cu(111) has been investigated in 0.1 M HClO4 by cyclic voltammetry, electrochemical scanning tunneling microscopy (STM), and surface-enhanced infrared adsorption spectroscopy (SEIRAS). Cyclic voltammetry showed the double layer region extending from -0.2 to 0.26 V and a pair of redox waves superposing on hydrogen evolution wave at more negative potentials. Diprotonated BiPy, BiPyH2 2+, is adsorbed flat on the Cu(111) (1 × 1) surface and forms a well-ordered monolayer with a (3 × 4) symmetry in the double-layer potential region. At more negative potential, BiPyH22+ is reduced to its monocation radical, BiPyH22+, and forms another well-ordered structure in which the radicals are stacked in molecular rows with a face-to-face self-dimer as the building unit. The SEIRA spectra of both BiPyH22+ and BiPy Ha2.+ are dominated by gerade modes which should be IR-inactive for the centrosymmetric species. The breakdown of the selection rule of IR absorption is ascribed to the vibronic coupling associated with charge transfer between BiPyH 2+ and the surface and between the radicals.

Original languageEnglish
Pages (from-to)3640-3646
Number of pages7
Issue number8
Publication statusPublished - Apr 11 2006
Externally publishedYes

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Spectroscopy
  • Electrochemistry


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