Au NANOPARTICLES BY LASER ABLATION IN WATER

1. Au NANOPARTICLES BY LASER ABLATION IN WATER Results AuPd Nanoparticles Abstract Introduction Results for Au Nps Without PEI Conclusions Acknowledgements Acknowledgements Acknowledgements M. A. Gracia-Pinilla1,2*, J. L. Menchaca2, M. Melendrez,2 J. Medel, and Eduardo Pérez-Tijerina1,2 1Laboratorio de Nanociencia y Nanotecnología, Centro de Investigación en Ciencias Físico Matemáticas (CICFIM), Facultad de Ciencias Físico-Matemáticas (FCFM) , Universidad Autónoma de Nuevo León, San Nicolás de los Garza, Nuevo León. México. 2 Centro de Investigación, Innovación y Desarrollo en Ingeniería y Tecnología (CIIDIT), Universidad Autónoma de Nuevo León, Apodaca, Nuevo León. México. *miguel.graciapl@uanl.edu.mx In the present work we showed the study of the capping of Au nanoparticles (NPs) by polyethyleneimine (PEI), we performed morphological, optical, chemical and structural characterization, by the use of the techniques of UV-Visible Spectroscopy, Zeta Potencial and High Resolution Transmission Electron Microscopy. The Au NPs were produced by a “Pulsed Laser Abrasion” in aqueous media, Au NPs are generated by irradiated with 1064 nm Nd:YAG laser with a fluence of 20 mJ/cm2 per pulse, the time of the pulse is 5 nanosecond. Ours procedure allows both a remarkable low range of sizes of the AuNps on the sample with size between 2 and 10nm with average of 5.3nm ± 1,6nm, and the high crystalline of the PEI-Au Nps compared to Au NPs with out PEI. Figure 2. Absorption spectra of Au nanoparticles in a) water, b) water with PEI 1mg/ml and c) water with PEI10mg/ml Diverse techniques has been used for preparation of metallic nanoparticles, we can mentioned that common used by chemical techniques involve first the reducing metal ions to metals atoms in presence or posterior to reduction by insertion of various complex or stabilizer agent (thiols, organic acids, amines and others) obtaining an partial functionalization of metallic nanoparticles by this way is possible optimized or controlled the grade of aggregation of the Metallic nanoparticles, examples of theses techniques are: Sol gel, impregnation, solvothermal, co-reduction and dendrimer-encapsulated, including more. By other hand, the physical methods involve the atomization or vaporization of the metals, alloys or complex oxides compound can be synthesized with diverse techniques where: sputtering, PVD, PLA, IGC1,2 and others, the principal vantage of theses techniques are the high reproducibility with excellent repeatability, but now arise new needs in the characteristic of the nanoparticles such as sizes selected1,2, disperse grade, fuctionalization of the surface, geometry preferential and in the case of alloys the degree of A-B segregation or mixing1, theses parameters are more relevant for metallic nanoparticles, as theses has interesting for the exceptional optical, electrical, catalytical, magnetical and antiviral properties in the range on 1-20nm, On of the major reasons for interest in avoid the coalescence process is the fact that their physical and chemical properties may be change modify the size of Nps. The Laser Ablation was carried output with nanosecond Nd:YAG Laser, which delivers 5ns full witch half-maximum (fwhm) pulses (wavelength: 1064 and 532 nm; repetition rate: 10 Hz; beam diameter: 6 mm). The laser beam was focused by a convex lens with a focal length of 100 mm onto a sample (Au sputtering target in 50 mL of desionizer water) contained in a pyrex glass containers of 100ml. ; the laser beam just in rear of the pyrex glass a diameter of 2.0-3.0 mm. The output energy of the laser was constant 20mJ/cm2, the Au sputtering target was incorporated into a system of rotation of 120rpm. For to evaluate the effect of the polymer capping over Au nanoparticles we made two sets of experiment, the first correspond to synthesis of Au nanoparticles without PEI capping and the second correspond to synthesis of Au nanoparticles with PEI capping, both experiments were performed under identical experimental conditions described previously. Posterior to synthesis, we evaluate the optical properties by UV-Vis spectroscopy, the structural and morphological propierties by HRTEM, and particles size and size distributions were measured by DLS ans Zeta potential data. a) Figure 3, HRTEM micrograph of Au nanoparticles without capping agent. a) Single Nanoparticles, b) aggregates of nanoparticles. b) a) b) • Au nanoparticles with high size control, were synthesized by pulsed laser ablation process, the precise control of size is obtained by controlling the synthesis parameters and the growth process (modifying the thermodynamics balance induced in the media aqueous by the capping agent). • With the polyethyleneimine (PEI) we can avoid the coalescence process of Au nanoparticles, also we founded that Au-PEI nanoparticles have high crystalline and five fold orientation preferentially in comparation of Au nanoparticles without (PEI) agent capping. c) Figure 1, Particles size by Zeta Potential of Au Nanoparticles without capping agent. The Zeta – potential values for theses Au nanoparticles is 24.23mV. Figure 3, HRTEM micrograph of Au-PEI nanoparticles. a) Au-PEI Single Nanoparticles (Icosahedral shape), b) Au-PEI nanoparticles with five fold orientations, and c) Au-PEI nanoparticles with decahedral shapes. BIBLIOGRAPHY • E. Perez-Tijerina, M.A. Gracia-Pinilla, S. Mejía-Rosales, A. Castro, U. Ortiz, and M. José Yacamán.., Highly size-controlled synthesis of Au/Pd nanoparticles by inert-gas condensation. Fararaday Discuss. 2008. 138. 353. • M.A. Gracia-Pinilla, E. Martínez, G. Silva and E. Pérez Tijerina, Masatake Haruta., Deposition of size selected Cu Nanoparticles by Iner Gas Condensation, Nanoscale Research Letters. 2010; 5: 180-188. This work was supported by the PROMEP grants UANL-PTC-289