**2. Experimental**

**1. Introduction**

terials.

ambient [6, 7].

Searching the literature we can observe that there is a huge amount of techniques that can be used for material preparation. As a matter of fact, for each group of materials there is a specific route more suitable to be used. An interesting conclusion we can make is the fact that unusual properties obtained in a specific material is sometimes related to the selected preparation method. To be more specific, not only the method used but also the solvent, the concentration, the manner, or the sequence in which the reaction components are mixed make these characteristics more pronounced when we are taking into consideration the preparation of nanoma-

198 Applications of Laser Ablation - Thin Film Deposition, Nanomaterial Synthesis and Surface Modification

On the other hand, among several methods developed in the last decade for material preparation, it can be observed that one stands apart: the pulsed laser ablation technique (PLA). The reason seems to be the high potential presented by the laser-based material processing for the thin solid film preparation, nanocrystal growth, surface cleaning and microelectronic device fabrication [1–5]. The pulsed laser ablation of solid materials was initially carried out in a conventionally evacuated deposition chamber and the majority of the results have focused on pulsed laser deposition (PLD) of solid targets in vacuum and in a diluted gaseous

Moreover, a slight modification of the PLD technique for materials preparation is the laser ablation in liquid environment (LALE). This technique has been extensively used at the beginning for the preparation of colloidal solution of metallic nanoparticles and subsequently as a successful technique for the fabrication of nanostructured metals oxide, nitrate and other materials of various compositions, morphologies and phases [8, 9]. Additionally, this technique nowadays can be considered a chemically clean and one-pot synthetic route by which a variety of functionalized new nanostructures can be prepared with a high yield of the final product

Compared with others techniques, LALE can be considered as a low cost experimental technique, which presents few controllable parameters and provides extreme experimental conditions of high temperature and pressure that favors the formation of unusual metastable phases. The technique consists of the interaction of a high-intense Laser pulse with a solid

without any by-products and, mostly, there is no need for further purification.

**Figure 1.** (a) Experimental set up for the LALE experiments (b) interaction diagram.

**Figure 1** shows the experimental set up used for all compounds preparation. For the target ablation, a second harmonic of a pulsed Nd:YAG laser (Spectra-Physics Quanta-Ray GCR-170 or a Quantel, model Brilliant B) is used, operating at 10 Hz with 8 ns of pulse width, with the beam focused on the target with a spot size of about 1 mm in diameter using a lens with a focal length of 50 mm. The synthesis processes differ from each other only on the Laser fluency used, ablation time, kind or type of target, solvent used and the proposed mechanism that explains its formation.
