**9. Laser ablation of gold nanoparticles in liquid**

Hence, they can absorb the energy of laser beam. This effect increases with increasing laser fluence because of the increase in the number of produced nanoparticles. Therefore, the intensity of laser beam that can reach the metal target is decreased. In addition, the size of the nanoparticles that absorb the incident laser beam decreases because of the laser-induced fragmentation occurs [68, 69]. This phenomenon was reported by Prochazka et al. [9]. They achieved the size of nanoparticles decreased when the laser beam interacted with the colloids during ablation of the metal target [70]. Consequently, the colloidal absorption causes the decreasing of the formation efficiency and the size of nanoparticles. This phenomenon called secondary effect. It can produce the high concentration nanoparticles and can control the formation process, and the size of nanoparticles and especially suppression of the ablation efficiency are undesired. Another considerable parameter is a flow-cell system, which is necessary for suppressing the colloidal absorption. Two colloidal absorption processes can be considered for preparation of metal nanoparticles. One is "interpulse" absorption and other is "intrapulse" absorption. The interpulse absorption related to the generation of nanoparticles by the earlier pulses stays in the laser beam path and absorbs the latterly coming pulses. The intrapulse absorption related to particles produced by the earlier part of one pulse immedi-

Many researchers reported the preparation of silver nanoparticles in organic and inorganic solutions. Silver nanoparticles have biological, thermal, optical, and electrical properties. Hence, the synthesis of silver nanoparticles was presented using chemical and physical methods. Laser ablation of silver plate is an alternative and green method to prepare the

**Figure 2.** (a) TEM image of silver nanoparticle in oil and (b) UV-visible spectrum of silver nanoparticles produced using

ately absorbs the later part of the same pulse.

72 Laser Technology and its Applications

laser ablation.

**8. Laser ablation of silver nanoparticle in liquids**

Gold nanoparticles (Au-NPs) have more applications for electronics [74], photodynamic therapy [75], therapeutic agent delivery [76], tumor therapy [77], sensors [78], drugs carriers [79], and medical diagnoses [80]. High activity and high sensitivity of Au-NPs have been fabricated using laser ablation in water [81]. The final product was used to reclaim the area of glassy graphite electrode for detection of Hg, Pb, Cu, and Co in the low concentration [81]. Gold nanoparticles can absorb and interact with the electrical field of laser beam [79], and Au-NPs generate localized surface plasmon absorption in the range of 400–900 nm [82]. The coherent excitation of free electrons causes the surface plasmon band in a colloidal nanoparticle [83]. The response of the Au-NPs to an interaction of laser beam depends on particle size, the surrounding material, and nanoparticle concentration [84]. Hence, the investigation and consideration of green synthesis of gold nanoparticles are intense interest subject in nanomedicine and nanotechnology area. Laser ablation technique is an alternative method for preparation of gold nanoparticles in an aqueous solution. Recently, gold nanoparticles were prepared in graphene oxide and vegetable oils such as pomegranate seed oil [25]. When gold nanoparticles were fabricated using laser ablation of the gold target, the nanoparticles were formed in the spherical shape (**Figure 3a**) that was investigated using transmission electron microscopy. The particle size was in the range of 20–5 nm, and the UV-visible absorption peak appeared about 530 nm (**Figure 3b**). In accordance with Mie theory, when the particle size decreases, the blue shift (∆*λ*) occurs in the localized surface plasmon absorption peak as follows:

$$
\Delta\lambda = \lambda\_o \times 0.18 \times \exp\left(\frac{-s}{0.23 \times D}\right) \tag{5}
$$

where *λ*<sup>0</sup> , *s,* and *D* are central wavelength, interparticle gap, and particle size in the central wavelength [85, 86].

**Figure 3.** (a) TEM image of gold nanoparticles in oil and (b) UV-visible spectrum of gold nanoparticles produced using laser ablation.

**11. Compression of silver, gold, and copper nanoparticles**

probes, sensor, and catalyst.

**12. Conclusion**

using laser ablation.

tion technique.

The silver, gold, and copper nanoparticles formed in the liquid solution in the spherical shape using pulsed laser ablation of plate, and they have the localized surface plasmon resonance peaks in the visible range; but the copper nanoparticle has tendency to convert copper oxide sooner than gold and silver nanoparticles. According to the literature, the gold nanoparticle was formed in the liquids faster than silver and copper nanoparticles [101]. Gold, silver, and copper nanoparticles have the different biological and medical applications. Gold nanoparticles were used as an antibiotic, anti-fungal, and anti-microbial agent. Gold nanoparticles were used for drug delivery and anti-cancer. Silver and copper nanoparticles are a strong anti-bacterial and anti-inflammatory. Gold and silver nanoparticles were used as optical

**Figure 4.** (a) TEM image of copper nanoparticle in oil and (b) UV-visible spectrum of copper nanoparticles produced

Laser Ablation Technique for Synthesis of Metal Nanoparticle in Liquid

http://dx.doi.org/10.5772/intechopen.80374

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Laser ablation is a green and simple method for fabrication of the metal nanoparticles without surfactant or chemical addition, and the properties of nanoparticles are unique. The wavelength of laser and laser intensity are the significant parameters for production of metal nanoparticles; hence, the formation efficiency of nanoparticles using infrared laser was lower than that using the green laser, and the thermal effect strongly appeared in the case of laser with nanosecond pulse. The particle size was in the range of 5–20 nm, and the nanoparticles were formed in the spherical shape in an aqueous solution using laser abla-
