11:00-11:40
Synthesis and Engineering of Nanostructures by ion beams
Dr. D.K. Avasthi (Inter University Accelerator Centre, India)
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Energetic ions play crucial role in synthesis and engineering of the nanostructures. Broadly, the areas of research and investigations of ion beams in nananostructuring are (i) synthesis of nanostructures and (ii) study of the modifications (by ion beams) of the existing buried nanoparticles in a matrix so as to explore the possibility of engineering the size and shape of the nanostructures. Inter university accelerator centre (IUAC) has the facilities to provide (i) 1-1.5 keV wide beam (2 inch diameter), (ii) typically ~100 keV to 1 MeV ions and (iii) swift heavy ions (energies from 50 MeV to 200 MeV). I will brief some results on the synthesis of noble metal nanoparticles embedded [1-4] in silica, ZnO and polymer matrix, along with some preliminary experiments on possible applications. The unique feature of the swift heavy ions, of crating ion tracks in insulators of dimension from a few nm to about 10 nm, is used to engineer the size and shape of the particles embedded in silica matrix. On the basis of several experiments at IUAC, it is shown that the embedded particles either grow [5] in size or reduce in size, if they are smaller then the ion track size. The shape transformation from spherical to elongated along the beam direction occurs [6], when the particle size is larger than the ion track in silica. The tuning of the surface plasmon resonance in noble metal particles embedded in insulating, transparent matrix [7,8] will be briefed. The unique feature of SHI is also used in creation of conducting C nanorods in fullerene matrix by irradiation of thin fullerene film by 100 MeV Au ions [9].
[1] D. K. Avasthi et al., Nanotechnology 18 (2007) 125604.
[2] S. Mohapatra et al., Appl. Phys. Lett. 92 (2008) 103105.
[3] Y. K. Mishra et al., Nanotechnology 18 (2007) 345606.
[4] D. Kabiraj et al., Nucl. Instr. And Meth. B244 (2006)100.
[5] Y.K. Mishra et al., Appl. Phys. Lett. 90(2007)073110.
[6] Y.K. Mishra et al., Appl. Phys. Lett. 91(2007)063103.
[7] R. Singhal et al, Appl. Phys. Lett. 93(2008)103114.
[8] R. Singhal et al., Jl. Appl. Phys. D 42(2009)155103 and Jl. of Appl. Phys. (in press).
[9] Amit Kumar et al, Jl. of Appl. Phys. 101(2007)014308.