ABSTRACT
Amorphous thin films of TiO2 deposited by Pulsed Laser Deposition (PLD) method are irradiated by Swift Heavy Ion (SHI) beam. The irradiated films are subsequently annealed by Rapid Thermal Annealing (RTA) method. Atomic Force Microscopy (AFM) study reveals formation of nano-rings on the surface after RTA processing. Phase change is identified by Glancing Angle X-ray Diffraction (GAXRD) and Raman spectroscopy. Optical characterisation is carried out by UV-VIS absorption spectroscopy. Though no shift of absorption edge is observed after irradiation, RTA processing does show redshift.
ABSTRACT
In the present study, we have analyzed the changes in surface morphology leading to formation of periodic structures known as ripples which arise due to an interplay between sputtering and surface diffusion. The 1.5 keV Ar atoms with a flux of 14.8 mA/cm2 are used in the present study. The InP(100) samples were bombarded at an incidence angle of 45 degrees to the normal at a base pressure of 1 x 10(-6) Torr at room temperature with fluences varying from 4 x 10(16) to 3.2 x 10(17) atoms/cm2. The rippled InP(100) surface was characterized with AFM. An increase in the ripple wavelengths, from 60 nm to 150 nm with the fluence has been observed. The width of the ripples varies from 38 nm to 128 nm and ripple amplitude varies from 0.8 nm to 16 nm with increasing fluence. One can control the dimension of the ripples in nano scale by controlling the fluence. Scaling studies have been performed to understand the mechanism responsible for such kind of surface evolution. The roughness parameter, alpha was found to be between 0.65 to 0.75 and the growth parameter, beta, as 1.14 +/- 0.12. The XPS characterization has also been employed to study the changes in the behavior of the InP with varying fluence.
ABSTRACT
In the present work, we report the formation of Au nanorings on quartz substrate by thermal evaporation of Au on quartz and subsequent annealing in certain conditions as a function of metal volume fraction and annealing temperature. Optical extinction cross-sections measurements and atomic force microscopy (AFM) studies have been performed on the as-deposited and annealed samples. No signature of nanoparticles formation is found in case of as-deposited samples, while spectra of annealed samples show a clear signature of surface plasmon resonance absorption (SPR) peaks around 580 nm, which reveals the formation of Au nanostructure. AFM images clearly show the formation of Au nanorings under certain conditions. The observed SPR frequency of the Au nanorings in our case is in agreement with the estimated frequency obtained from the formulation of Aizpurua et al. Optical extinction measurements at different incidence angles were performed, which showed splitting of SPR at angles beyond 20 degrees.
Subject(s)
Crystallization/methods , Gold/chemistry , Nanostructures/chemistry , Nanostructures/ultrastructure , Nanotechnology/methods , Hot Temperature , Macromolecular Substances/chemistry , Materials Testing , Molecular Conformation , Particle Size , Surface PropertiesABSTRACT
In the present work, magnetic force microscopy is employed to investigate the magnetic ordering in ion irradiated fullerene films. It is observed that magnetic domain size is approximately 100-200 nm and magnetic signal is stronger at the domain boundaries. Magnetic signal arise in irradiated films is confirmed by magnetic measurements using a superconducting quantum interference device which increases with the ion fluence. The induced magnetism is possibly due to structural defects in the amorphous carbon phase formed by ion irradiation.
