publication detail
Quadratic nonlinearities of gold nanoprisms in solution: the role of corner sharpness
AUTHORS
Document type
Poster communications
Résumé
The size and shape (nanospheres, nanorods, nanostars…) of metallic nanoparticles significantly affect their physical and chemical properties. Among these nanostructures, acentric objects are expected to display high quadratic nonlinear responses, especially hyperpolarizability β values, as measured via the Harmonic Light Scattering technique in colloidal NP water solutions. In this work, we report the influence of surface area and shape of metallic nanoparticles, spheres, rods and triangles on their β values. In particular, we synthesized gold nanoprisms (GNPs) by seedless growth. The second harmonic response of these GNPs has been investigated experimentally and theoretically with edge length ranging from 40 to 116 nm and for different curvature radii at corners. Their calculated and experimental hyperpolarizabilities β are found to display, not only a linear dependence with the surface area as reported for spherical metallic nanoparticle shapes, but also a strong influence of their corner sharpness. The high experimental and theoretical β values of GNPs are mainly assigned to the sharpness of tips, as confirmed by systematic calculations performed on gold nanoprisms with various edge lengths and corner radii, showing that the effect of corner sharpness dominates over centrosymmetry breaking. These results shed new light on the SHG properties of acentric, sharp corner gold nanoparticles, and open the way to the investigation of various noble metal nanopolyhedra (e.g. nanocubes) to develop new families of highly nonlinear metallic nanostructures making use of an increased number of facets and of the sharpness of related geometric singularities.