Analytical and Bioanalytical Chemistry

, Volume 407, Issue 27, pp 8197–8204 | Cite as

Tip-enhanced Raman spectroscopic imaging shows segregation within binary self-assembled thiol monolayers at ambient conditions

  • Wan-Ing Lin
  • Feng Shao
  • Bruno Stephanidis
  • Renato ZenobiEmail author
Research Paper
Part of the following topical collections:
  1. Nanospectroscopy


Phase segregation of coadsorbed thiol molecules on a gold surface was investigated with nanoscale chemical imaging using tip-enhanced Raman spectroscopy (TERS). Samples were prepared using mixed solutions containing thiophenol (PhS) and an oligomeric phenylene-ethynylene (OPE) thiol, with 10:1, 2:1, and 1:1 molar ratios. Phase segregation into domains with sizes from ≈30 to 240 nm is observed with these molar ratios. A comparison of TERS images with different pixel sizes indicates that a pixel size bigger than 15 nm is not reliable in defining nanodomains, because of undersampling. In this study, the formation of nanodomains was clearly evident based on the molecular fingerprints provided by TERS, while ambient scanning tunneling microscopy (STM) was not capable of discerning individual domains via their apparent height difference. TERS therefore allows to image nanodomains in binary self-assembled monolayers, which are invisible to methods solely relying on topographic or electron density characteristics of self-assembled monolayers. Moreover, TERS mapping provides statistical data to describe the distribution of molecules on the sample surface in a well-defined manner. Peak ratio histograms of selected TERS signals from samples prepared with different mixing ratios give a better understanding of the adsorption preference of the thiols studied, and the relationship of their mixing ratio in solution and adsorbed on the surface.


Thiols Raman spectroscopy Imaging Self-assembled monolayers TERS Segregation 



This work was financially supported by the SALSA program at Humboldt University, Berlin, and by the EMRP NEW02 project “Metrology for Raman spectroscopy.” The EMRP is jointly funded by the participating countries within EURAMET and the European Union. We would like to thank Lothar Opilik and Jacek Szczerbiński for helpful discussions.

Supplementary material

216_2015_8840_MOESM1_ESM.pdf (976 kb)
ESM 1 (PDF 976 kb)


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Copyright information

© Springer-Verlag Berlin Heidelberg 2015

Authors and Affiliations

  • Wan-Ing Lin
    • 1
  • Feng Shao
    • 1
  • Bruno Stephanidis
    • 1
  • Renato Zenobi
    • 1
    Email author
  1. 1.Department of Chemistry and Applied BiosciencesETH ZurichZurichSwitzerland

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