Statistical study of Gold Nanoparticles Produced by Laser Ablation in Water

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1 Australia Joural of Basic ad Applied Scieces, 6(7): , 2012 ISSN Statistical study of Gold Naoparticles Produced by Laser Ablatio i Water Hassa Zare Asl ad Mia Eslamifar Physics Departmet, Behbaha Uiversity of Techology, Behabaha, Ira Abstract: Due to their small dimesios, aoparticles ad materials cosistig of ao-sized buildig blocks exhibit uique mostly superior properties, well differig from their bulk couterpart. Sice a effectig method to produce aoparticles is laser ablatio, a study was performed o the geeratio of particles durig laser ablatio with emphasis o size distributio measuremets. Experimetal productio of gold aoparticles upo the ablatio of metal targets i deioized water, caused by irradiatio with a Nd:YAG laser is studied. The aoparticles emergig i a liquid were ivestigated usig UV-visible absorptio spectroscopy, ad trasmissio electro microscopy. The result display effectiveess of laser ablatio i producig uiformly sized ad pure gold aoparticles. Also it was cofirmed that colloidal gold aoparticle solutios exhibit a distict Plasmo resoace at 530m respectively. Key words: Gold aoparticles, Laser ablatio, UV-visible, Trasmissio Electro Microscopy, Particle size distributio. INTRODUCTION Metal aoparticles, with diameters ragig roughly betwee 1 ad 100 aometers, are atural bridges betwee molecules ad exteded solids. They ope up a ew field i fudametal sciece ad because of their potetial techological applicatios. Due to the sigificat icrease i surface compared with volume, aoparticles show uique properties. The domiace of the surface behavior provides the possibility to cotrol most material properties without chage i chemical compositio such as: meltig poit, magetic properties ad eve color of materials. A few applicatios of aoparticles iclude: use as catalysts [Safavi et al., 2008], drug carriers [Yua et al., 2008] ad productio of aochips [Limo et al., 2009], aotubeds [Zhu et al., 2009] ad aowires [Su et al., 2007]. I all these cases i order to use aoparticles, cotrollig the size ad shape of aoparticles ad their purity is of utmost importace. Therefore special attetio should be paid to particle size distributio produced ad its purity. I recet years, metal aoparticles suspeded i a solutio to display differet optical, magetic, ad electroic properties from bulk materials, have attracted much attetio. The most commoly used methods to prepare metal aoparticles i solutio is the chemical reductio of metal ios [Chou ad Re, 2000]. I these chemical methods, the shape ad size of aoparticles produced caot be cotrolled. Also, due to the presece of chemicals, colloidal solutio of aoparticles produced is ot pure. I recet years a ew method for producig metal aoparticles i solutio has bee developed. I this method, a target immersed i a liquid is irradiated by a pulsed laser which i tur produces pure aoparticles i the solutio. To cotrol the aoparticles size, the first importat step is to acquire a greater uderstadig of the process of aoparticles geeratio ad evolutio durig laser ablatio. This paper aims to achieve such kowledge usig experimetal study o creatig gold aoparticles by laser ablatio. The results showed that usig such experimetal setup productio of gold aoparticles with regular spherical shape, well particle size distributio ad purity is possible. 2. Experimetal Setup: The experimetal apparatus used i this study is show i figure 1. The output of a Nd:YAG laser was used for ablatio. 1 gram gold bullio (Suisse Fie Gold 99.99%) immersed i 5ml deioized water, was irradiated with a focused 1064 m beam of a pulsed Nd:YAG laser with 5Hz repetitio. The spot size of the focused laser beam was 1.0mm. The laser pulse width was 30 s ad irradiatio was cotiued for 15 miutes with a eergy output of 50Mj per pulse. Durig the irradiatio, due to laser beam collisio with gold bullio, the material quickly plucked from the surface ad was throw ito the ambiet fluid. As a result of this process gold colloidal solutio was produced. Durig this process, clear water slowly was coverted to a purple color. Correspodig Author: Hassa Zare Asl, Physics Departmet, Behbaha Uiversity of Techology, Behabaha, Ira. addresses: HassaZareAsl@Gmail.com Tel: ; fax:

2 Fig. 1: Experimetal apparatus used for productio metal aoparticles by laser ablatio i liquid medium. 3. Results ad Commets: 3.1. Ultraviolet visible Spectrometry: Oe of the methods used for aoparticle characterizatio, especially i liquid medium is a UV-visible Spectrometry. I this study, i order to prepare UV-visible spectra from a gold colloidal solutio, Cary-100 spectrometer was used. The compariso betwee the absorptio spectrum of water ad gold colloidal solutio is show i figure 2. This spectrum shows a maximum at 530 m, which correspods to the surface plasmo absorptio that is uique for gold aoparticles. Maximum absorptio of gold aoparticles obtaied i this experimet, has a good agreemet with the maximums obtaied i other studies [Kazakevich et al., 2006, Dolgaev et al., 2002]. Fig. 2: (Series 1) Absorptio spectra of Au colloids obtaied by laser ablatio, (Series 2) Absorptio spectra of water. Light iteractio with the aoparticles strogly depeds o size, shape ad compositio of the aoparticles ad the eviromet cotais these particles. Solutio of the problem of absorptio ad scatterig of light by a small particle ivolves solvig Maxwell s equatios with the correct boudary coditios, ad also usig Mie theory ad assumig aoparticles are spherical, this solutio results i calculatig the locatio of the Plasmo peak. After these calculatios, the scatterig ad extictio cross sectios ca be calculated from: sca (2 1)( a ) 2 b k 1 (1) 2 ext Re( a ) 2 b k 1 (2) The coefficiets a ad b i Eq. (1) ad Eq. (2) are give by 294

3 a a m m m m (3) (4) I which ad are Ricatti-Bessel fuctios of order, the particle) ad m p m x kr is a size parameter (R is the radius of is the square root of the ratio of the dielectric fuctios of the particle ad of the medium. By replacig the values for gold aoparticle with a radius of 10 m ad parameters for water as the medium aoparticles exist i, gives the Plasmo peak of 530 m [Chhatre et al., 2012]. This shows good agreemet with values obtaied from the gold aoparticles produced i this experimet Trasmissio Electro Microscopy (TEM): Oe of the best methods for aoparticles characterizatio is usig a Trasmissio Electro Microscopy (TEM). The TEM images ivolve appropriate iformatio about the size ad shape of aoparticles [Müller et al., 2008]. Gold aoparticles images show i the figure 3 were prepared by a TEM model CM200 FEG ad Maufactured by Philips Compay. The microscope works i the voltage of 200kv. For preparig images of a colloidal solutio, Small amouts of colloidal solutio were poured o grade ad were dried i desiccators. The operatio was repeated several times (10 to 20 times) util sufficiet umbers of aoparticles were placed o the grid. Figure 3 shows images of gold aoparticles colloid i water, prepared by trasmissio electro microscopy 30 days after productio ad figure 4 also shows the particle size distributio curve of each image. I these images, the particles were measured by the Microstructure Measuremet software ad particle size distributio curves of aoparticles were plotted i Microsoft Excel. It should be oted that the particle size distributio curves were plotted after roudig the primary particle sizes. 295

4 Fig. 3: TEM images of Au aoparticles produced by laser ablatio i water. Fig. 4: The particle size distributio curve of Au aoparticles. Figure 5 shows the distributio of particle size related to 1529 gold aoparticles colloid i water that was studied usig the 30 TEM images. 296

5 Fig. 5: The distributio of particle size related to 1529 gold aoparticles colloid i water that was studied usig the 30 TEM images. 4. Coclusio: Experimetal productio of gold aoparticles usig laser ablatio i water medium was studied i this research. Notable features of gold aoparticles produced via this method are their regular spherical shape ad purity of the resultig colloidal solutio. Results show that most particles have a size rage from 0 to 15 m, with the average size equal to 9.49 m ad stadard deviatio is These values are idicative of very good size distributio. REFERENCES Chhatre, A., P. Solasa, S. Sakle, R. Thaokar, A. Mehra, Color ad surface plasmo effects i aoparticle systems: Case of silver aoparticles prepared by microemulsio route, Colloids ad Surfaces A: Physicochemical ad Egieerig Aspects, 404: DOI : /j.colsurfa Chou, K., C. Re, Sythesis of aosized silver particles by chemical reductio method, Materials Chemistry ad Physics, 64: DOI: /S (00) Dolgaev, S.I., A.V. Simaki, V.V. Voroov, Shafeev, Naoparticles product by laser ablatio of solid i liquid eviromet, Applied Surface Sciece, 186: DOI: /S (01) Kazakevich, P.V., A.V. Simaki, V.V. Voroov, G.A. Shafeev, Laser iduced sythesis of aoparticles i liquids, Applied Surface Sciece, 252: DOI: /j.apsusc Limo, O., L. Busiaro, A. Gerardio, L. Bitto, A. Frydma, Z. Zalevsky, Fabricatio of electro optical ao modulator o silico chip. Microelectroic Egieerig, 86: DOI: /j.mee Müller, S.A., U. Aebi, A. Egel, What trasmissio electro microscopes ca visualize ow ad i the future, Joural of Structural Biology, 163: DOI: /j.jsb Safavi, A., G. Absala, F. Bamdad, Effect of gold aoparticle as a ovel aocatalyst o lumiol hydrazie chemilumiescece system ad its aalytical applicatio. Aalytica Chimica Acta, 610: DOI: /j.aca Su, C., P. Che, S. Zhou, AgCl aoparticle aowires fabricated by template method, Materials Letters, 61: DOI: /j.matlet Yua, Q., R. Vekatasubramaia, S. Hei, R.D.K. Misra, A stimulus-resposive magetic aoparticle drug carrier: Magetite ecapsulated by chitosa-grafted-copolymer. Acta Biomaterialia, 4: DOI: /j.actbio Zhu, W., G. Wag, X. Hog, X. She, D. Li, X. Xie, Metal aoparticles chais embedded i TiO2 aotubes prepared by oe-step electrodepositio, Electrochimica Acta, 55: DOI: /j.electacta