Figure 1.

Preliminary photochemical experiments and schematics. (a) Diagram of silver reduction procedure where free carriers created via optical absorption in titanium oxynitride travel through the TiO₂ surface oxide layer and reduce Ag⁺ ions from solution, which leads to nucleation of Ag colloids on the film surface. Dark-field images of the titanium oxynitride film surface immersed in the Ag solution prior (inset) and after laser illumination (785 nm). Selective formation of silver clusters on the surface of the film using laser excitation of electrons in the TiON can be clearly seen, forming the ICL acronym. (b) Diagram and dark-field images for the same experiment but using a TiO₂ film as substrate. As it can be seen from the dark-field images prior to (inset) and after laser excitation, there is no silver deposition in this case. (c) Schematic diagram of pump–probe spectroscopy used throughout this work where a high power pump pulse excites carriers in a sample, the influence of which on the optical response is then measured using a time-delayed probe pulse. Scale bars correspond to 5 μm in every case.