Confocal Raman and TEM measurements at the same area on nanoparticles

We have studied Cu–Ag core-shell nanoparticles using a confocal Raman setup reducing the number of probed nanoparticles from 108 for a macroscale to 103–104. This advance represents a significant step towards resolving the signature of a single particle. Cu–Ag core-shell and pure Ag nanoparticles have been identified on the same spectra. The size and form of these nanoparticles deduced from Raman spectra are in agreement with the ones measured by transmission electron microscopy (TEM). The intensity of the micro-Raman signal has been correlated with the exact distribution of nanoparticles obtained by TEM on the same area. Two Raman signatures depending on the acoustic mismatch between Cu core and Ag shell have been pointed out and correlated to the different orientations of their crystallographic axis.