Small-angle X-ray scattering method to determine the size distribution of gold nanoparticles chemisorbed by thiol ligands

The scattering profiles of gold nanoparticles prepared by means of two different methods were measured by the small-angle X-ray scattering, the profiles were found to be well reproduced by F-distribution function. This result suggests that the two methods yield nanoparticles with different average diameters and different diameter dispersions. The average diameter of dodecanethiol-chemisorbed nanoparticles prepared by the direct chemisorption method was 1.9 nm, and the diameter of particles prepared by the ligand-exchange method was 4.0nm. These values were consistent with the value determined by transmission electron microscopy. The crystallite size was determined by wide-angle X-ray diffraction analysis, and the results indicated that the nanoparticles, even those that were 4 nm in size, were single crystals.