Mechanical coupling between gold nanoparticles
Adrien Girard, Hélène Gehan, Alain Mermet, Jérémie Margueritat, (Soprano team) et Aurélien Crut, (Femtonanooptics team), in collaboration with Lucien Saviot from Laboratoire Interdisciplinaire Carnot de Bourgogne, published an article entitled «« Mechanical coupling in gold nanoparticles supermolecules revealed by plasmon-enhanced ultralow frequency Raman spectroscopy » dans la revue Nanoletters.
In this paper the authors highlight a novel Raman vibrational mode associated with the mechanical coupling among neighbor nanoparticles (a few nm) through a polymer matrix. It is shown that this mode comes from the hybridization of the dipolar Lamb modes of individual nanoparticles. The detection of this mode at very low frequencies. (ν <10GHz or 3 cm-1) was permitted thanks to the selectivity of the Raman probe via the resonant excitation of the optical coupling between nanoparticles leading to spectacular enhancement (like in SERS) of the low frequency Raman signal. These results were achieved through the development of a micro-spectrometer Fabry-Perot versatile in wavelength. The origin of this vibration mode has been understood thanks to models that reproduce well the experimental frequencies. This study opens new and promising perspectives for the study of the mechanical coupling at the nano-scale.