Superlattices of silver nanoparticles passivated by mercaptan

Two- and three-dimensional superlattices of passivated silver nanoparticles were formed on amorphous carbon films by the self-assembly technique. The x-ray diffraction (XRD) and x-ray photoelectron spectroscopy results demonstrated that the colloid system was composed of silver nanoparticles and, on the surface of the silver nanoparticles, the chemical bond was formed between the S of the 1-nonanethiol and the Ag of the particle. XRD and transmission electron microscopy also showed that the instability of the silver nanoparticles mainly resulted from the growth of the nanoparticles. Due to the relatively close-packed thiol layer on the surface of the nanoparticle, in the infrared spectra of the silver nanoparticles, absorption peaks of the terminal methyl group and methylene stretching modes were red shifted; meanwhile the transverse modes of the binding absorption disappeared. (author)