Electroactive molecular layers produced by reduction of an aryldiazonium salt scrutinized by Tip Enhanced Raman Spectroscopy

Surface modification methodologies are continuously refined, which in parallel necessitates accurate analytical methods to probe their chemical composition at the nanoscale. We describe here our electrochemical and Tip Enhanced Raman Spectroscopy results on surfaces modified through reduction of an electroactive aryldiazonium salt. Grafting may be first triggered electrochemically. In this case, thick and disorganized layers are produced, with important changes in spectral responses in comparison to the parent system. Conversely, spontaneous reduction of the salt also occurs during simple immersion in the diazonium solution, which leads to low surface coverages ( i.e. thin layers) and preservation of the molecular backbone of the molecule. This study highlights the advantages of TERS to recover chemical information at the nanoscale even for complex surface modification processes.