Two-Colour Sum-Frequency Generation Spectroscopy Coupled to Plasmonics with the CLIO Free Electron Laser

Nonlinear plasmonics requires the use of high-intensity laser sources in visible and near/mid-infrared spectral ranges to characterise potential enhancement vibrational fingerprint chemically functionalised nanostructured interfaces aimed at improving molecular detection threshold nanosensors. We used Two-Colour Sum-Frequency Generation (2C-SFG) nonlinear optical spectroscopy coupled European CLIO Free Electron Laser order highlight an energy transfer organic inorganic built on a silicon substrate. evidence that pollutant, such as thiophenol molecules adsorbed small gold metal nanospheres grafted silicon, was detected monolayer scale 10 µm infrared range, with increasing SFG intensity three specific phenyl ring vibration modes reaching two magnitude orders from blue green–yellow excitation wavelengths. This observation is related strong plasmonic coupling vibrations. The high level aggregation substrate allows us dramatically increase presence hotspots, revealing collective plasmon based local electric fields between nanoparticles packed close contact configuration favors Raman active modes, for which 2C-SFG particularly efficient this unusual range.