Effect of size and surface modification on first hyperpolarizability of CdS nanoparticles

Summary form only given. We measured the values of the first hyperpolarizability /spl beta/ for aqueous suspensions of CdS nanoparticles by a hyper-Rayleigh scattering (HRS) technique. The samples consisted of nanoparticles with three types of surface: as-prepared (Cd/sup +2/-rich surface stabilized by polyphosphate), modified by OH/sup -/, and Pt-loaded. The samples were characterized by UV-visible absorption spectroscopy and by transmission electron microscopy (Carl Zeiss, TEM 902, 80 keV). The nanoparticle sizes were estimated from UV-visible absorption spectra using the well-established relationship between absorption and size for panicles in the quantum confinement regime. The /spl beta/ values were determined from HRS measurements using a Q-switched Nd-YAG laser. The orientation averaged hyperpolarizability was determined from the intensity of the doubled frequency light by external and internal reference methods.