Papers by Author: Onanong Chamlek

Abstract: The lithium lanthanum borate glasses doped with Dy₂O₃ were prepared by the melt quenching technique. The Dy₂O₃ doped concentration has been increased and substituted B₂O₃ from 0.00 to 1.50 mol% in the glasses. The photoluminescence, optical absorption and physical properties of these glasses have been investigated in this work. The experimental results show that, the molar volume of glasses tended to increase with increasing of Dy₂O₃ concentration, but the density were not depending on the concentration of Dy₂O₃. The UV-Vis-NIR spectra, absorption bands at 451, 798, 894, 1085 1264 and 1676 nm have been observed. For Dy³⁺ doped glasses, emission bands centered at 483, 575 and 664 nm have been observed with 388 nm excitation wavelength. The emission spectra have shown the strongest band in the glasses with 0.50 mol% Dy₂O₃ concentration.

Abstract: Copper Phthalocyanine (CuPc) thin films have a potential to use as nitrogen dioxide (NO2) gas sensor therefore the study of property modification of CuPc thin film by NO2 gas can lead to a better understanding the sensor operation. CuPc thin films were prepared by thermal vacuum deposition on glass substrate and aluminum interdigitated electrodes. The film characteristics were investigated with and without NO2 gas. These characteristics indicated that the resistance of CuPc film decrease as the NO2 concentration increases. In order to achieve high efficient of sensing properties, the post-deposition film was also annealed. The surface modifications were investigated with different exposed time of NO2 gas. Their properties modifications before and after annealing were investigated on the film morphology and crystalline structure. The surface morphology of the film was examined by atomic force microscopy while the crystalline structure of the film was determined by x-ray diffraction. The electrical measurements of CuPc film exposed to NO2 gas were studied in order to investigate property modification of the CuPc film.

Abstract: Iron phthalocyanine (FePc) thin films prepared by thermally evaporated from as received and purified powders were studied. The molecular interaction between FePc thin films and acetone vapor was studies by X-ray photoemission spectroscopy (XPS) and optical absorption spectrometer. The core level XPS spectra and optical absorption spectra showed slightly different between the spectra before and after acetone exposure. For FePc film evaporated with purified powder, only the Fe 2p3/2 spectra at about 712 eV appeared and the height of peak dramatically decreased. Iron K-edge X-ray absorption near edge structure (XANES) spectra was used to investigate iron atom in as received and purified powders and also study the interaction between FePc molecule and methanol vapor. The X-ray diffraction pattern of as received, annealed and purified FePc powder were investigated to study the crystal reformation and Raman spectroscopy was used to investigate iron atom vibration in as received FePc film.