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Home Teaching Publications Curricuum vitae Ph.D Thesis Group Page Research Grants Department Home |
Computational Chemsitry Projects 1. Investigation of structure, dynamics and energetics of mixed transition metal clusters Clusters are the aggregates of atoms, ions or molecules and can contain from two to as many as thousand of particles. Their properties lie between the isolated atoms and the bulk solids. The physical and chemical properties of clusters often change radically with their sizes, the stoichiometry and spatial distributions of different components if clusters contain more than one element. Therefore, one of the most important reasons for interests in clusters is the possibility to tune their physical and chemical properties by varying the size and the compositions. Small free metallic particles of nanometer size have given rise to a large amount of work, because of both a fundamental interest for describing new condensed phases (novel structural forms) between the molecule and solid state, and the some attractive properties in catalysis or magnetism. In isolated atoms, almost all elements show a non-vanishing magnetic moment given by the Hunds rules while in the solid state only a few of them (some transition metals of the Fe group, lanthanides and actinides) preserve a non-vanishing magnetization. Because nanoclusters are in between these two extremes, it has been known that free transition metal nanoclusters have novel magnetic properties; nonmagnetic elements in bulks found to be showing ferro-magnetism in nanostructures and clusters, These observed magnetic ordering in clusters of atoms and monolayer films of normally nonmagnetic materials and enhancing magnetization in nonmagnetic materials is because of narrowing electron bands as a result of reduced coordination number and higher symmetry in law-dimensional systems. Pure transition metal nanostructures have been subjected to extensive investigation for electronic and magnetic properties by experimentalists and theoreticians. But use of binary alloy clusters opens a new field to tailor magnetic properties. It might be possible to enhance the magnetic moments in nanoparticles above values known from pure materials using binary 3d transition metal alloys with a very high magnetic moment. Goals of this project are to determine the structures, dynamics and energetic of mixed transition metal clusters. These will help to find the novel structures for technological various applications. In addition to the potential applications of small clusters and nanostructures in nanoelectronic and memory devices, they are very important in homogeneous nucleation, crystal growth, catalysts, and understanding the structure of amorphous materials. Molecular Dynamic Simulation and Density Functional Tehory (DFT) calculations using the Gasussian 03 package are the major simulations techniques Experimental Solid State Chemistry Projects 1. Preparation and characterization of semiconductor oxide thin films Currently, we use various sources such as synthetic liquids, gaseous fuels, nuclear power, hydro power, wind power and solar energy etc., to generate our daily energy needs. The synthetic liquids and gaseous fuels mainly produced by refining of the petroleum (crude oil) are the major energy sources for combustion engines in industries and transportations. Considering Sri Lanka, our electricity generation was mainly based on hydropower and it is gradually changing to petroleum plants with increase of demands due to industrialization, population growth and climate change. In addition to this, use of petroleum product in transportation is also causing much damage to our economy due to our heavy dependence on imported crude oil. It is the fact that according to general Chemistry knowledge, combination of hydrogen molecules and oxygen molecules would generate energy which can be used in the place of petroleum products. Its byproduct, water, is also environmental friendly and no health problems will arise. Hydrogen as a fuel in vehicles are already tested and used in some developed countries. As a tropical country, we can use sunlight as our major energy source and can be used in photogeneration of hydrogen from water by means of available materials such as Cu2O and redox systems such as Fe2+/Fe3+. Main objectives of these studies are preparations and characterizations of Cu2O and ZnO semiconductor materials using simple low cost methods, and then investigate their ability to photosplit water. Determination of optimum conditions for various factors such as film thickness, redox couple concentrations, time duration are also a major objective in this study to find out the effective use of these semiconductor materials in photogeneration of Hydrogen by splitting of water. 2. Investigation of adsorption properties of semiconductor oxides for gas sensing As a developing country, Sri Lanka is facing a major challenge in air pollution arising with industrialization and rapid increase in number of motor vehicles on roads. Colombo is in seventeenth position of World Health Organization rating on most affected countries and cities from Air Pollution. It reveals that certain air pollutants such as sulfur dioxide, carbon monoxide, carbon dioxide, and nitrogen oxides are rich in atmosphere in Colombo urban area. These harmful gases cause health effects and it has been reported increased hospital admissions for respiratory diseases and heart diseases, school and job absences from respiratory infections, or aggravation of chronic conditions such as asthma and bronchitis. In addition to the industrialization and more vehicles on roads, introduction of thermal power plants, which is a necessity in Sri Lanka to solve electrical power crisis in the country, is an added cause to the air pollution. With this trend, it is important to develop gas sensors to monitor the change of hazardous gases present in the environment. Therefore, the objective of this study is to develop gas sensors based on semi-conducting materials to monitor air quality and to develop an alarm system. In this project, we use the oxide films being devloped under projects 1. |