Superlattice structure of an organic adsorbate on Au(111) in an aqueous electrolyte as probed by in situ second harmonic generation

Sunghyun Kim, Ming Zhao, Daniel Alberto Scherson, Kee Ju Choi, In Tae Bae

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The superlattice structure of 2,5-dihydroxythiophenol (DHTP) irreversibly adsorbed on Au(111) in 0.1 M perchloric acid was determined in situ based on dual resonant, rotational anisotropy, second harmonic generation (RA-SHG) measurements. Plots of the intensity of the SH light as a function of the azimuthal angle displayed two clearly defined 3-fold pattern features. These curves were analyzed in terms of a model which regards the total interfacial nonlinear susceptibility as the sum of contributions due to the molecular overlayer itself and due to the attenuated substrate. A statistical fit to these data was found to be consistent with a (√7 × √7)R19.1° superstructure for the DHTP/Au(111) adlayer for which the surface coverage (θ) is 1/7. This value of θ was found to be in excellent agreement with that calculated from the normalized charge under the surface-confined two-electron hydroquinone/quinoane voltammetric peaks observed for the same precise DHTP/ Au(111) interface.

Original languageEnglish
Pages (from-to)9383-9386
Number of pages4
JournalJournal of physical chemistry
Issue number38
Publication statusPublished - 1994 Jan 1
Externally publishedYes


ASJC Scopus subject areas

  • Engineering(all)
  • Physical and Theoretical Chemistry

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