Hyper-Rayleigh scattering of CdS nanoparticles with different surfaces

The first-order hyperpolarizability beta values of two kinds of CdS nanopar ticles with different surfaces were experimentally determined in solution v ia an incoherent hyper-Rayleigh scattering (HRS) technique. It is found tha t the P value of CdS nanoparticles capped with 2,2'-bipyridine is 4.27 x 10 (-27) esu which is about a factor of 3 smaller than the beta value (1.30 x 10(-26) eSu) Of bare CdS nanoparticles whose surface is not modified by org anic groups. This difference is interpreted in terms of a two-level model a pproximation derived from molecular chromophores, when considering the cont ribution of moleculelike scatterers at the particle surfaces.