Synthesis AgO Nanoparticles by Nd:Yag Laser with Different Pulse Energies

: One technique used to prepare nanoparticles material is Pulsed Laser Ablation in Liquid (PLAL), Silver Oxide nanoparticles (AgO) were prepared by using this technique, where silver target was submerged in ultra-pure water (UPW) at room temperature after that Nd:Yag laser which characteristics by 1064 nm wavelength, Q-switched


Introduction:
Physical and chemical materials properties greatly differ between nano to micro size 1 . Metal nanoparticles NPs with a high surface area, high density of active sites exposed to reactants, are significant for heterogeneous catalysis. Preparing metal oxide, metal nanoparticles in a simple technique may be made using Pulsed Laser Ablation in liquid environments (PLAL) 2,3 .
The laser ablation process is affecting strongly with characteristics of a laser beam used (number of pulses, wavelength, pulse duration, and energy) 4 -7 ablation rate direct proportionality with laser pulses number that influenced in the case of dielectrics, semiconductors, and single metals 2,[8][9][10] . The pulse laser ablation in liquids used for nanomaterial synthesis has many unique advantages compared with other synthesis techniques like synthesis Lu and Sm sesquioxide nanoparticles by using Nd:Yag laser-irradiated for 30 min, spherical particles form with particle size 62.35-75.02 nm was formed 11 . Cu2O NPs synthesized by used (Nd: Yag laser, 1064 nm, and 7 ns) pulsed laser ablation on a copper plate immersed in liquid media (ultra-pure water), the particle sizes were affected and decreased by increasing the repetition rates of a pulsed laser where characterized by measured (laser-induced breakdown spectroscopy, UV-visible spectroscopy, and X-ray diffraction) 12 Silver/zinc oxide nanoparticle structure synthesis using a pulsed laser ablation in liquid (PLAL) technique. The concentration of silver was effect by changed time of target ablation from one to five min. the photocatalytic ability of zinc oxide increased by modulation with silver than pure zinc oxide and facilitated a higher degradation rate of R6G 13 . Ag/Au (core/shell) nanoparticles (NPs) synthesis using pulse laser ablation in water with Q-switch Nd: YAG laser (wavelengths 532nm and 1,064nm ,different energy range 0.2 J to 1J, and repetition rate 1Hz) to create Ag/Au NPs , Ag nanocolloid first prepared via ablation target, this ablation related to Au target at various energies. Surface morphology, Surface Plasmon Resonance (SPR), and average particle size were identified by employing: scanning electron microscopy (SEM), UV-visible spectrophotometer, and transmission electron microscopy (TEM) 14 .
Laser ablation defines as a process of removing small masses from the material surface with the laser beam. Laser ablation process is based on many applications like modification surface of materials, nanoparticles formation, and deposition of thin film, chemical analysis, and micromachining. Laser ablation process relies on ablated material properties (optical and thermal) as well as laser parameters 9, 15-21 .
Silver (Ag) oxide is used for several applications, used in gas sensing 22 , other important applications of silver oxide in biological activity and medical applications [23][24][25][26] .
In this paper, the effects of different pulses energy of Nd:Yag laser beam with wavelength (1064 nm) has been studied to ablated AgO Nanomaterial and the interaction effect.

Synthesis of AgO nanoparticles
The PLAL technique is used to prepare colloidal solution of AgO nanoparticles. Silver metal target is immersed in 50ml of Ultra-Pure Water (UPW) 0.45µS/cm and Nd:Yag laser 1064 nm, 6Hz, 6ns with different pulse laser energies 1000mJ, 500mJ and 100 mJ irradiation on immersed silver metal target . Each time 500 pulses were used to produce the AgO nanoparticles. Fig.1 shows schematically of ablation setup. Some different of measured tests were used to characterize the prepared silver NPs like: SEM, AFM, XRD, and UV-visible spectroscopy.

Results and Discussion: a) Crystalline Structure Analysis
Growth of silver nanoparticles crystalline structure was characterized and identification by Xray diffraction (XRD). Diffraction patterns result of prepared AgO nanoparticles is shown in Fig. 2 at different laser energy 1000 mJ, 500 mJ, and 100 mJ respectively. All Silver nanoparticles, which are prepared at room temperature 25°C can be indexed as faced centered cubic (FCC) with strong intensity peak at (111) direction. The peaks give an indication that the product is at high purity.
The average size of the produced AgO nanoparticles can be calculated from the peak broadening using Scherer equation 17 = 0.9 cos ….1 Where: D represents the nanoparticles' mean diameter, λ is XRD wavelength = 1.54A°, θB refers to Bragg angle and βFWHM is X-ray peaks' full width at half maximum. In addition, diffraction patterns have been used to calculate the lattice constant and the results with particle size values are 5.5 nm, 13nm and 19 nm respectively for laser pulse energy 1000 mJ, 500 mJ, and 100 mJ. Our results show a good agreement with those obtained 27,28 .

B) SEM analysis
The micrograph images of morphological studies for AgO nanoparticles done with SEM and obtained results are shown in Figs 3, 4 and 5 respectively for silver NPs prepared with laser pulse energy 1000 mJ, 500 mJ, and 100 mJ. The nanoparticles have almost spherical shape, grow individually, and make a few agglomerates over the surface.

c) Atomic Force Microscope (AFM) analysis
Surface morphology, particle size, and roughness of the surface for prepared silver NPs was studied by AFM (SPM AA2000, Angstrom advanced, and used contact mode) under normal atmospheric conditions. Fig. 6 displayed Surface morphology result at 1000mJ pulse energy. A 3D image shows fine particles, small particle size of 32.45nm, and the histogram of granularity cumulation distribution appearing that 50% of particle size was 30 nm. A surface roughness analyzing determined by AFM, surface roughness RMS (Root Mean Square) was 2.62 nm and average roughness was 1.96 nm and a cross section curve show regular distribution for particles in height and smooth surface roughness. At 500 mJ, Fig.7, the 3D AFM image shows particle size of about 64.3nm and from the distribution histogram appeared that 50% of diameter was 50 nm. Surface roughness (RMS) was 2.81 nm and average roughness was 2.11nm. The cross section curve show distribution for particles in range 9 -21nm in height and peaks rather wide in width and the aggregation was appearance by the height and width of peaks. At 100 mJ pulse laser energy, Fig. 8, AFM 3D image shows a distribution of particles and particle size of 67.86 nm. The distribution histogram shows that 50% of diameter was 55nm. Surface roughness (RMS) was 2.96 nm and average roughness was 2.12nm that characterizes the surface roughness. The cross section curve show distribution of particles as peaks and the surface roughness in middle.  9 shows the absorption spectra of prepared silver NPs at wavelength 440nm for pulse energies 1000, 500, and 100 mJ, Optical properties measured by Shimadzu UV-1650 PC UV-Visible Spectrophotometer at wavelength range of 340 -550 nm. The decrease of pulse laser energy leads to increase silver nanoparticles particle size and the optical absorption spectra that due to Surface Plasmon Resonances (SPR) phenomenon where the particle size and aggregation of nanoparticles effected on the absorbance of incident light than the intensity and lead to increase optical absorption 29 . Figure 9. The absorbance spectra of prepared silver NPs with 1000 mJ, 500mJ, and 100mJ laser pulse energy.

Conclusion:
Pulsed Laser Ablation in Liquid (PLAL) process by using Nd:Yag laser (1064 nm wavelength, Q-switched, and 6ns pulse duration) with various pulses energy 1000 mJ, 500 mJ, and 100 mJ, 500 pulses used to synthesis silver oxide nanoparticles .The structural peaks for silver oxide nanoparticles indexed as face-centered cubic (FCC) type and crystalline orientation (111) plane. The particle size increased 32.45, 64.3, and 67.86 nm respectively for 1000, 500, and 100 mJ, this affected on optical properties of nano particles, the absorption spectra increased as decrease in pulse laser energy because of the increase of particle size and aggregation of partials. As a pulse laser energy increased, the particle size decreased.

Acknowledgment:
All Authors Acknowledgment to the AL-Nahrain Nanorenewable Energy Research Center, Al-Nahrain University, Department of Chemical Engineering, College of Engineering Al-Nahrain University and Department of Chemistry, College of Science, Al-Nahrain University for participate and contribute the work of this research