Pronounced Odd-Even Changes in the Molecular Arrangement and Packing Density of Biphenyl-Based Thiol SAMs: A Combined STM and LEED Study

W Azzam, P Cyganik, G Witte, Manfred Buck, C Wöll

Research output: Contribution to journalArticlepeer-review

147 Citations (Scopus)

Abstract

Self-assembled monolayers (SAMs) of omega-(4'-methylbiphenyl-4-yl) alkanethiols CH3(C6H4)(2)(CH2)(n)SH (BPn, n = 3 and 4) on Au(111) substrates were studied using scanning tunneling microscopy (STM) and low-energy electron diffraction (LEED). Preparation at elevated temperature results in highly ordered layers with large domains. Whereas the (2root3 x root3) structure of the BP3 SAMs is similar to that reported previously for other aromatic thiols SAMs made from BP4 exhibit a very different structure. A (5root3 x 3)rect unit cell containing 8 molecules is found which corresponds to a packing density reduced by 25% compared to that of BP3. The odd-even effect observed in the molecularly resolved STM images of BP3 and BP4, therefore, confirms the pronounced influence of the spacer chain on the structure of these biphenylbased SAMs.

Original languageEnglish
Pages (from-to)8262-8270
Number of pages9
JournalLangmuir
Volume19
Issue number20
DOIs
Publication statusPublished - 30 Sept 2003

Keywords

  • SELF-ASSEMBLED MONOLAYERS
  • SCANNING-TUNNELING-MICROSCOPY
  • AU(111)
  • GOLD
  • ADSORPTION
  • SURFACES
  • DESORPTION
  • ARENETHIOLS
  • SULFUR
  • SILVER

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