In this work, we present fabrication of ZnO nanostructures by pulsed laser deposition in air at atmospheric pressure. The use of this technology leads to formation of nanostructures composed by nanoparticles and nanoaggregates. These nanostructures possess a large surface-to-volume ratio, which makes them suitable for gas-sensor application. The samples were exposed to NH3 and the effect was investigated of light irradiation on the gas response and recovery time of the sensor element. It was found that the response of the sensor element increases even by irradiation by sunlight. The gas sensing properties of the ZnO nanostructures were compared when irradiated by light of different wavelengths.
This study is focused on the selective laser removal of chlorine-containing corrosion products from artificially corroded samples of copper, brass and steel. Its goal is to find an efficient methodology for laser cleaning of historical metallic objects. The laser treatment is done with two laser sources: Q switched Nd:YAG laser generating nanosecond pulses at 1 Hz repetition rate in the IR (1064 nm) and the green (510.6 nm) spectral range, and copper bromide vapor laser (CuBrVL) generating nanosecond pulses at 20 kHz repetition rate in the green (510.6 nm) spectral range. The cleaning is performed in dry and wet conditions. The surfaces before and after the treatment are characterized using optical microscopy (OM), x-ray fluorescence spectroscopy (XRF), x-ray diffraction spectroscopy (XRD), and laser-induced breakdown spectroscopy (LIBS).
This paper presents a method for fabrication of oriented multicomponent nanowires composed by nanoparticles. The technology is based on nanosecond pulsed laser deposition of mixed target in the presence of an external magnetic field. The targets used for the ablation process consist of Fe2O3 and Ag2O with different ratio between them. The laser ablation is implemented in air at atmospheric pressure by using Nd:YAG laser system operated at 1064 nm. SEM analysis of the surface of the as-deposited samples reveals a presence of micrometric nanowires which are predominantly oriented in the direction of the magnetic field. These nanowires are composed by arranged nanoparticles formed in the plasma plume. The influence is investigated of the Fe2O3/Ag2O ratio in the target on the morphology and optical properties of the structures. Surface plasmon resonance band of Ag nanoparticles was observed in the transmission spectra of the samples with the highest Ag content. The material composition of the samples was identified by EDX and XRD analyzes. The obtained structures can find application in the fields of nanoelectronics, spintronics, magneto-optics and plasmonics.
The fabrication of nano-crystalline carbon films was implemented by the application of pulsed laser deposition (PLD) technology. The experiments were performed in a standard on-axis laser ablation (LA) configuration. The third harmonic of a Nd:YAG laser was used for ablation of a microcrystalline graphite target. All experiments were performed in vacuum at a pressure of 1×10-3 Pa for different deposition times. (001) Oriented silicon (Si) covered by either 350 or 450 nm silica (SiO2) layer was used as a substrate. The films have a thickness between 4 and 40 nm and are characterized by X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, atomic force microscopy (AFM) and ellipsometry measurements. We established deposition of nano-sized graphene-like films on top of predominantly amorphous carbon films with a thickness of 1- 2 nm. The measured the (n and k) and determined the values for the forbidden gap of the films which are between 0.01 eV and about 1 eV with reference to the sp3 hybridized carbon content of the film.
We report the fabrication of gas sensor elements by pulsed laser deposition in air at atmospheric pressure. We focused our attention on metal-oxide semiconductors, namely, SnO2, TiO2 and MoO3 and studied the samples’ structure and morphology. The deposition technology applied leads to the formation of nanostructures composed of nanoparticles and nano-aggregates. We report preliminary results on the gas-sensing properties of the metal-oxide nanostructures. The sensors were exposed to CO, acetone and ethanol, with the TiO2 nanostructure demonstrating the highest response to CO exposure.
Different types of ZnO nanostructures were fabricated on metal (Au or Ag) coated silicon substrates by applying the pulsed laser deposition (PLD) method. The samples were prepared at substrate temperatures in the range of 300 – 650 °C, oxygen pressure of 5 Pa, and laser fluence ≤ 1 J.cm-2– process parameters usually used for thin-film deposition. The metal layer is essential for the preparation of nanostructures. The nanostructures grown at different substrate temperatures showed obvious morphological differences. The substrate temperature increase led to changes in the morphology of the nanostructures from nanowhiskers to nanowalls when a thin Au layer was used. It was also observed that the type and thickness of the metal layer affect the morphology of the nanostructure.
Pulsed laser deposition was used together with a glancing angle deposition technique in order to produce suitable metal substrates for surface enhanced Raman scattering (SERS) applications. The surface morphology, crystallinity, optical properties, and enhancement factor of these substrates were investigated. Rodamine-6G was used as a SERS active molecule pumped at 785 nm. The Au nanorods with average lengths of 50 – 70 nm having diameter in the range of 10 – 20 nm exhibited a SERS enhancement factor of 105. The as-prepared metal substrates were found to meet the criteria of a sensitive, uniform, and easily produced SERS substrate.