CdS nanoparticles with diameters from 14 -120 Angstrom and very narrow
size distributions are studied by x-ray absorption fine structure spe
ctroscopy between 5 and 296 K. Clear trends in the Cd-S distance as a
function of size and surface stabilization of the nanoparticles could
be observed. Particles with thiols as ligands show an expansion of the
Cd-S distance with decreasing particle size whereas polyphosphate sta
bilized samples are slightly contracted with respect to CdS bulk. The
static disorder of the nanoparticles is enlarged with respect to the b
ulk. In contrast, the dynamic behavior of the nanoparticles shows a sl
ight stiffening of the Cd-S vibration with decreasing particle size. M
easurements of the third moment of the pair distribution function indi
cate the possibility to distinguish between cubic and hexagonal struct
ures in CdS nanoparticles.