Grazing-incidence small-angle X-ray scattering property of double-layered gold nanoparticle arrays

Gold nanoparticle arrays fabricated via layer-by-layer technique were investigated using grazing-incidence small-angle X-ray scattering (GISAXS) method. Samples containing two gold nanoparticle layers that were separated by 5, 11, 15 and 21 polyelectrolyte (PE) interlayers were studied. By using different X-ray incident angles, correlations of gold nanoparticles (GNPs) in the same layer and in two different layers were investigated. It is found that both sideway correlations between GNPs in the same layer and vertical correlation between two gold nanoparticle layers depend on the thickness of PE interlayers. According to sideway correlation, the size of GNPs is determined to be (13.0 +/- 0.5) nm in all of the four samples, which was also proved by scanning electron microscopy (SEM) and theoretical calculation of form factor of spherical particles. From vertical correlation, distance between two gold nanoparticle layers was determined for sample with 11, 15 and 21 PE layers. These distances can be reasonably explained with the number of PE layers and the thickness of single PE layer. These results indicate that by repeated depositing of oppositely charged PE layers, a true three-dimensional (3D) nanostructure can eventually be designed.

Automated summary

Gold nanoparticle arrays fabricated through layer-by-layer technique were studied using GISAXS method. The sideway and vertical correlations between gold nanoparticles in the same layer and between different layers were found to depend on the thickness of polyelectrolyte interlayers.