Chemical imaging of interfaces by sum-frequency generation microscopy: Application to patterned self-assembled monolayers

We demonstrate molecule-specific imaging of a chemically patterned self-assembled monolayer by IR-visible sum-frequency microscopy. The pattern on an Au substrate consists of microcontact printed 10 mum wide alkanethiolate stripes embedded in omega-carboxyalkanethiolate adsorbed from solution. We use both electronic and vibrational contrast mechanisms for a quantitative analysis of thiolate density and the coverage of the two molecular species. The evaluation of images taken at three different IR wavelengths suggests a substantial intermixing of the two thiolates occuring in the preparation procedure. (C) 2003 American Institute of Physics.