atomic molecular physics rajkumar pdf 37

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Abstract
: Self-assembled germanium islands have been grown on Si (001) substrates using solid source molecular beam epitaxy. A series of annealing experiments have been performed at a temperature 650°C in order to clarify some issues related to island stability and coarsening mechanism. The shape and size distribution of Ge islands as a function of annealing time up to 90 min have been studied through atomic force microscopy. Foot-prints of the annealed and etched islands have demonstrated that the coarsening is dominated by coalescence mechanisms rather than the Ostwald ripening. A detailed Raman characterisation, using optical phonons as efficient probes in analysing self-organised Si1-xGex islands, is reported. The alloy composition has been determined from the Raman intensities. The experimental results are in good agreement with the strain relaxation obtained from X-ray rocking curve and data from AFM topographic images. The generic mechanisms for the growth of self-assembled Ge islands as a function of growth parameters and post-growth treatment are also reviewed.


Large-scale molecular dynamics simulations are performed to investigate the atomiclevel stresses on InAs/GaAs mesas. The simulations are based on an interatomic-potential scheme for InAs/GaAs systems which depends on the local chemical composition. Multiresolution techniques are used to speed up the simulations. InAs/GaAs square mesas with  101 -type sidewalls are studied. The atomic-level pressure distribution and surface atomic stresses on the sidewalls with 12, 10, 8 and 6 monolayers of InAs overlayers have been calculated.



Research Interests
My research focuses on the organization of the microscopic interactions between atoms and molecules in condensed phases of materials including biomaterials. This research involves large scale dynamical simulations of systems in condensed phases, computational statistical mechanics algorithms, physics of elemental and molecular clusters, development of model potentials and molecular dynamics modeling, applications of quantum chemistry to nanoscience, and machine learning discovery in solid state and soft materials including biomaterials.


Development of ceramic nanoparticles with improved properties has been studied with much success in several areas such as synthesis and surface science. Examples of ceramic are silica, alumina, titania, zirconia, silicon nitride, silicon carbide, and so forth. Advancement in nanotechnology has led to the production of nanosized silica, SiO2, which has been widely used as filler in engineering composite. The silica particles extracted from natural resources contains metal impurities and not favorable for advanced scientific and industrial applications. Thus, focus is given to synthetic silica (colloidal silica, silica gels, pyrogenic silica, and precipitated silica), which is pure and produced mostly in amorphous powder forms compared to natural mineral silica (quartz, tridymite, cristobalite) which are in crystalline forms [6]. As shown in Figure 1, various methods that have been used to obtain silica particles can be categorized into two main approaches: top-down and bottom-up [2, 7]. Top-down is characterized by reducing the dimension of the original size by utilizing special size reduction techniques (physical approach). Bottom-up or chemical approach involves a common route used to produce silica nanoparticles from atomic or molecular scale. Some of the widely used methods to synthesize silica nanoparticles are sol-gel process, reverse microemulsion, and flame synthesis. The sol-gel process is widely used to produce pure silica particles due to its ability to control the particle size, size distribution and morphology through systematic monitoring of reaction parameters.



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Atomic Molecular Physics Rajkumar Pdf 37

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