ToF-SIMS study of 1-dodecanethiol adsorption on Au, Ag, Cu and Pt surfaces

Time-of-flight secondary ion mass spectrometry (ToF-SIMS) has been used to perform a chemical analysis of long-chain thiol (CH3(CH2)(11)SH)-treated gold, silver, copper and platinum surfaces. All the mass peaks from positive and negative ion spectra within the range m/z = 0-2000 u are studied. ToF-SIMS data revealed that on gold, silver and copper substrates 1-dodecanethiol form dense standing-up phases, but on platinum being a catalytically active substrate, we were able to identify also surface-aligned parallel lying molecules in addition to a standing thiolate layer. Our study shows that when ToF-SIMS spectra are analyzed, not only the existence of oligomers but also metal + hydrocarbon fragments give information about the order of SAM. Copyright (c) 2008 John Wiley & Sons, Ltd.