Laser-induced growth of monodisperse silver nanoparticles with tunable surface plasmon resonance properties and a wavelength self-limiting effect

We present a method for the tunable production of monodisperse silver nanoparticles. Using monochromatic light of different laser wavelengths to irradiate an initial solution of seed crystals, the size and shape of the products can be controlled. By monitoring the absorption spectrum during growth, it is found that initially the absorption maximum shifts to longer wavelengths and broadens, indicating an increase in particle size and size dispersion. Remarkably, this effect comes to a halt and reverses, displaying a shift to shorter wavelengths and simultaneously narrower bandwidths until, on completion, a final size and relatively narrow distribution are reached. The final size and shape is found to depend on laser wavelength and-power. Both discs and triangular prisms as well as pyramidal and pentagonal prisms may be produced. A mechanism based on a wavelength-dependent self-limiting process governed by the surface plasmon resonance controlling the photochemical reduction of particles is suggested.