The development of high-quality tin monosulphide (SnS) layers is one of the crucial tasks in the fabrication of efficient SnSbased optoelectronic devices. Reduction of strain between film and the substrate by using an appropriate lattice-matched (LM) substrate is a new attempt for the growth of high-quality layers. In this view, the SnS films were deposited on LM Al substrate using the thermal evaporation technique with a low rate of evaporation. The as-grown SnS films were characterized using appropriate techniques and the obtained results are discussed by comparing them with the properties of SnS films grown on amorphous substrate under the same conditions. From structural analysis of the films, it is noticed that the SnS films deposited on amorphous substrate have crystallites that were oriented along different directions. However, the SnS crystallites grown on Al substrate exhibited epitaxial growth along the [101] direction. Photoluminescence (PL) and Raman studies reveal that the films grown on Al substrate have better optical properties than those of the films grown on amorphous substrates.
Abstract:The use of Alternanthera sessilis, which is commonly known as Mukunuwenna in Sri Lanka as a source of chlorophyll was examined. The extraction of chlorophyll was carried out using buffered 80 % (v/v) aqueous acetone. The optimum operating conditions such as solvent to A. sessilis ratio, extraction temperature and extraction time were found to be 5 mL/g, 50 °C and 45 minutes, respectively. The yield of chlorophyll a and chlorophyll b under these optimum operating conditions were 659 and 261 µg/g of A. sessilis, respectively. Mechanical grinding of A. sessilis gave a higher yield as compared to blanching and drying. Refrigeration at 15 °C was found to be ideal for storing of fresh A. sessilis up to 3 days without a considerable loss of chlorophyll content. Chlorophyll extraction could be modelled successfully using basic mass transfer equations up to 30 °C. It failed above this temperature due to the degradation effect. Kinetic study on the degradation of chlorophyll extracted from A. sessilis confirmed first order reaction model and the effect of temperature on the rate constant was also adequately modelled by the Arrhenius equation.
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