In the present study silver nanoparticles (Ag-NPs) were prepared by using chemical synthesis. Silver nanocolloid solution has been prepared chemically by the reduction of silver salt using sodium borohydride (NaBH4) and trisodium citrate (C6H5Na3O7.2H2O). Triangular silver nanoplates were also prepared by reducing silver salt using ascorbic acid which is a mild reducing agent. The nanoparticles were characterized by UV-VIS spectrophotometry and Scanning Electron Microscopy (SEM). The reducing character of ascorbic acid was used to determine the amount of ascorbic acid in real sample like vitamin C tablets that are available in the market of Bangladesh. Dhaka Univ. J. Pharm. Sci. 12(1): 29-33, 2013 (June) DOI: http://dx.doi.org/10.3329/dujps.v12i1.16297
The formation of an octadecyl monolayer on a hydrogen terminated Si(111) surface in neat octadecene at 200 °C was followed by attenuated total reflectance Fourier transform infrared (ATR FT-IR) and sum frequency generation (SFG) spectroscopy and ellipsometry. Until ca. 60% of the monolayer was formed, the monolayer formation proceeded with simple first-order reaction kinetics and the monolayer was disordered. As the coverage steadily increased, the order of the monolayer became very high and the rate of the monolayer formation became significantly slower.
The decomposition processes of an organic monolayer, which was formed on Si(111) via a Si-C covalent bond, induced by exposure to UV light irradiation or ozone, were investigated using attenuated total reflectance Fourier transform infrared spectroscopy. Exposure to both ozone and UV light resulted in a reduction of the intensities of the IR peaks corresponding to CH stretching vibration and bending scissors and the appearance of peaks corresponding to CO stretching and COH in-plane bending. The latter peaks initially increased, reached a maximum, and then decreased, indicating that the monolayer was decomposed through the formation of intermediates such as aldehyde and carboxylic acid. The monolayer was also decomposed by exposure only to UV light or ozone but more slowly as the time dependencies of the CH peaks showed. While the peaks corresponding to the CO stretching and the COH in-plane bending behaved similarly under the condition of exposure to ozone, they were not observed during decomposition induced by UV irradiation. These results show that, while the monolayer was decomposed through the formation of oxidized intermediates such as aldehyde and carboxylic acid under the condition of exposure to ozone, the decomposition of the monolayer under the condition of UV irradiation proceeded via cleavage of Si-C bonds by photogenerated electrons or holes without such oxidized intermediates. An increase of gauche defects as the decomposition proceeded was demonstrated by sum frequency generation spectroscopy.
In the present study Cu nanoparticles (NPs), ZnO nanorods have been deposited on indium tin oxide (ITO) electrode and thereby Cu-NPs /ZnO / ITO composite film electrode has been prepared. The prepared nanostructures have been characterized by using scanning electron microscope (SEM). The shape of the electrochemically deposited ZnO follow rod like structure on ITO electrode, CuNPs follow irregular spherical shape when electrodeposited on ITO electrode. Oxidation of ascorbic acid on bare ITO electrode is favorable than that of ZnO modified ITO electrode but Cu-NPs/ ZnO composite electrode had high sensitivity and stability and showed higher catalytic current for glucose oxidation. DOI: http://dx.doi.org/10.3329/jasbs.v39i2.17855 J. Asiat. Soc. Bangladesh, Sci. 39(2): 183-190, December 2013
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