Laser ablation in liquid was utilized to prepare a TiO₂ NP suspension in in deionized distilled water using Q-switch Nd: YAG laser at various laser energies and ablation times. The samples were characterized using UV–visible absorption spectra obtained with a UV–visible spectrophotometer (UV-Vis,) Fourier transform infrared (FTIR), X-ray diffraction (XRD), and transmission electron microscope (TEM). While, UV-Vis spectra showed the characteristic band-to-band absorption peak of TiO₂ NPs in the UV range. FTIR analysis showed the existence of O-Ti-O bond. XRD patterns indicated the presence of (101) and (112) plane crystalline phases of TiO₂. TEM images showed a spherical-like structure of TiO₂ NPs with various size distributions depending on the ablation period. It was also found that there is a relationship between laser ablation time and TiO₂ NP size distribution, where longer ablation times led to the smaller size distribution. The antibacterial activity of TiO₂ NPs was evaluated with different species of bacteria such as Escherichia coli, Pseudomonas aeruginosa, Proteus vulgaris, and Staphylococcus aureus, using the liquid approach. The optimum activity of TiO₂ NPs is found to be against E. coli at 1000 μg mL⁻¹. Furthermore, adding, TiO₂ NPs (1000 μg mL⁻¹) in the presence of amoxicillin has a synergic effect on E. coli and S. aureus growth, as measured by the well diffusion method. However, both E. coli (11.6 ± 0.57mm) and S. aureus (13.3 ± 0.57mm) were inhibited by this process.

The coupling between sub-bandgap defect states and surface plasmon resonances in Au nanoparticles and its effects on the photoconductivity performance of TiO2 are investigated in both the ultraviolet (UV) and visible spectrum. Incorporating a 2 nm gold nanoparticle layer in the photodetector device architecture creates additional trapping pathways, resulting in a faster current decay under UV illumination and a significant enhancement in the visible photocurrent of TiO2, with an 8-fold enhancement of the defects-related photocurrent. We show that hot electron injection (HEI) and plasmonic resonance energy transfer (PRET) jointly contribute to the observed photoconductivity enhancement. In addition to shedding light on the below-band-edge photoconductivity of TiO2, our work provides insight into new methods to probe and examine the surface defects of metal oxide semiconductors using plasmonic resonances.

This work shows the enhancement of the visible photocatalytic activity of TiO₂ NPs film using the localized surface plasmonic resonance of Au nanostructures.

Various features of Silicon micro and nanostructures have been produced by lasers. Laser micromachining of silicon wafer has been conducted to fabricate devices for microelectronic circuits. The laser beam initiates a chemical reaction between the silicon and HF acid to synthesize porous layers by a laser-induced etching process. It is found that the etching rate increases for longer laser wavelengths when CW lasers are used and could also be used to drill micro holes in the silicon wafer when higher laser power densities are used. While Q-switched Nd:YAG laser could be employed to produce ordered nanostructures. It is found that laser parameters are adequate to produce and control the micro/nanostructure characteristics. The surface morphology investigation reveals formation of porous layers of various structures and different laser parameters were affected differently on the surface morphology. Moreover, the SEM statistics imply that high pore density of smaller average pores diameters of 3μm are obtained when the HF concentration diluted to 30%. Furthermore, gratings of submicrons scale can be made when proper processing parameters are selected precisely. Experimental analysis has been carried out to characterize the microstructured surface using computer software