| Abstract
| - The goal of this study is to elucidate the formation of molecular gradients made of semifluorinated organosilanes(SFOs) on flat substrates by using a methodology developed by Chaudhury and Whitesides (Science 1992, 256, 1539).We use surface-sensitive combinatorial near-edge X-ray absorption fine structure (combi-NEXAFS) spectroscopy tomeasure the position-dependent concentration and orientation of SFO molecules in SFO molecular gradients on flatsilica surfaces. Using the combi-NEXAFS data, we establish the correlation between the fraction of the F(CF2)8(CH2)2− species on the substrate and the average tilt angle of the −(CF2)8F group in the SFO as a function of thedeposition gas medium (air vs nitrogen) and the end group around the silicon atom (monofunctional vs trifunctional).In addition, we utilize the gradient geometry to comprehend the mechanism of formation of SFO self-assembledmonolayers (SAMs). Specifically, we provide evidence that depending on the nature of the end group in the SFO andthe vapor phase the SFO molecules add themselves into the existing SAMs either as individual molecules or asmultimolecular complexes.
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