Stimulated Low-Frequency Raman Scattering in LaF3 Suspensions

We observe stimulated low-frequency Raman scattering (SLFRS) caused by laser pulse interaction with acoustic vibrations of nanoparticles in water suspensions of LaF3 nanoparticles. We show that frequency shifts of the scattering correspond to the eigenfrequencies of nanoparticles vibrations. LaF3 nanoparticles were synthesized in the presence of glycine by a double jet precipitation technique at various initial concentrations of reagents. We investigate the morphologies and particle sizes as well as size distributions of the particles prepared using transmission electron microscopy (TEM) and dynamical light scattering (DLS). In view of the absorption spectroscopy, we show that the reaction system components and products have no absorption in the visible region, including lambda = 694.3 nm. From the luminescence spectroscopy, we find also that they do not emit at lambda = 694.3 nm excitation.