Laser-assisted synthesis of ultra small metal nanoparticles

Palladium nanoparticles have (to our knowledge) for the first time been synthesized in the liquid phase by photolytic decomposition from their ammine complexes. Short pulses (full-width at half-maximum, FWHM 15 ns) of 193 nm excimer light were used in the experiments. The particles were probably formed by a photolytic decomposition of excess ammonia yielding atomic hydrogen, which in turn reduces the metal ions to metal. The particles were characterized by transmission electron microscopy (TEM), high resolution scanning electron microscopy, Raman spectroscopy, X-ray fluorescence spectroscopy (XRFS) and X-ray diffraction. The size of the metal particles, as measured by TEM, could be varied in the range 1–5 nm by varying the experimental parameters such as laser fluence and reactant concentrations. X-ray and electron diffraction revealed that the particles consisted of the pure metal.