Laser-induced deposition of gold nanoparticles and its applications to analytical sciences

Pulsed-laser irradiation of thiol-passivated gold nanoparticles in cyclohexane resulted in a rapid agglomeration and fusion of gold nanoparticles due to a partial desorption of immobilized thiol molecules. At the same time, a patterned deposition of gold nanoparticle corresponding to the shape of the laser spot was found on the surface of a substrate that was immersed into a colloidal solution. In order to extend this phenomenon to practical and analytical applications, some basic investigations, spectroscopic studies for elucidating the deposition mechanism and the effects of a surface modification of the glass plate were carried out. It was found that the quantity and size of the deposited gold nanoparticles were dramatically changed only by a partial replacement of the immobilized dodecanethiol with 1,6-hexanedithiol, and were also dependent on the wavelength and the power of the laser light. Independently, laser-induced patterned deposition was carried out onto a glass plate and a membrane filter, and subsequent electroless copper plating catalyzed by the deposited gold nanoparticles, and applications to surface plasmon resonance sensing and surface-enhanced vibrational spectrometry have been successful.