Figure 4.

Sketch of the first reference SFG experiments performed on interfaces constituted of 15 nm diameter AuNPs synthesized by Turkevich method. (a) Scheme of the DODAC/AuNPs/Si interface (no grafting of AuNPs or DODAC molecules at any step). Each constituent is just deposited or spread, respectively. The corresponding SFG signal displays the five strong methyl and methylene peak-shaped vibration modes of the DODAC molecules (picture adapted from reference [31]). (b) Scheme of the DDT/AuNPs/Glass interface (grafting of AuNPs on glass through APTES and chemical functionalization of AuNPs by DDT molecules). The corresponding SFG signal displays the five weak methyl and methylene dip-shaped vibration modes of the DDT molecules (picture adapted from reference [53]).