Papers by Keyword: Spectral Properties

Abstract: The complex of di-(2-methyl-8-hydroxyquinoline) zinc (Zn (2-mq)₂) was synthesized. The complex was characterized by elemental analysis, ¹HNMR, ¹³CNMR, infrared, UV-vis, XRD and molar conductivity. The zinc (II) ion was found to coordinate to the oxygen atom of phenolic hydroxyl and nitrogen atoms of 2-methyl-8-hydroxyquinoline and the complex conformes to 1:2 metal-to-ligand stoichiometry. The fluorescence properties of the complex in solid and solution were studied. The complex exhibits yellow light under the excitation of UV light. The solvent factors influencing the fluorescent intensity are discussed.

Abstract: Chemical bath deposited nickel oxide (NiO) thin film samples were grown at room temperature of 30 °C on glass substrates. Samples k₁, k₂, and k₃ were annealed for one hour at temperatures of 100 °C, 200 °C and 300 °C respectively, while as grown sample k₄ served as a reference. A second set of samples k₅, k₇, and k₈ were annealed at a constant temperature of 300 °C for time durations of 1H, 2H and 3H respectively, with as grown sample k₆ as a reference. The spectral absorbance, transmittance and reflectance of all the thermally treated thin film samples were measured with a spectrophotmeter (D model Avantes Spec 2048 version 7.0) in the UV-VIS-NIR region of 300-900 nm wavelength. The results show distinctive variations in all the spectral properties for different combinations of annealing time and temperature, each starting at a threshold wavelength of 300 nm and ending with a distinctive minimum or maximum value. Deduced graphical values of the refractive index also show distinctive variations. For annealing time of 3 hours at a temperature of 300 °C, the results produced symmetric reflectance and symmetric refractive index with maximum values of 8% and 0.293 occurring at 500 nm wavelength and photon energy of 2.5 eV respectively. Direct transition band gap energy obtained for all the samples lie between 3.68-3.84 eV. The results reported in this paper clearly indicate that optimum combinations of production parameters of nickel oxide thin films can yield specific values of the properties for specific applications.

Abstract: Ho3+:Tm3+:BaY2F8(Ho:Tm:BYF) laser crystal was grown by Czochralski method. The technical parameters as follows: the seeding temperature is 955°C; the pulling rate is 0.5mm/h; the rotation rate is 5rad/min; the cooling rate is 15°C/h; the period of growth is 6d. According to the spectra of crystal sample, the strongest absorption peak exists at 781nm, and the absorption cross section is 6.16×10-21cm2. While the strongest emission peak exists at 2056nm with the FWHM of 38nm, and the emission cross section is 4.05×10-21cm2, and the emission mechanism at 2056nm was analyzed based on energy level diagram of Ho3+ and Tm3+ ions.

Abstract: In this paper, the crystal growth, ceramic preparation and performance of Yb: YAG was studied systematically. The new technics that is filling protective atmosphere in the lower vacuum has been presented firstly. The Yb: YAG laser with a dimension of Φ27mm×100mm was grown by Czochralski method to medium frequency induction heating. The performance of Yb: YAG crystal was investigated by using several measurements, such as absorption spectrum, fluorescence spectrum and so on.

Abstract: A new schiffbase ligand, methyl-2-pyridyl ketone benzoyl hydrazone (L), and its complexes with rare earth nitrates have been synthesized. These new complexes with the general formula of Ln(L)₂(NO₃)₃·nH₂O(where Ln = La, n = 5.5; Ce, Pr, n = 5; Nd, Eu, n = 4 ) were characterized by mass spectra, elemental analysis, IR spectra, thermal analysis, UV spectra, molar conductivity and luminescent spectra. All the complexes are stable in air. The results show that the lanthanide ion in each complex are coordinated by oxygen and nitrogen atoms of the ligand, the oxygen atoms of the nitrate and coordinated water molecules. The amide-oxygen atoms of L coordinate to the Ln ions in its keto-form. Tentative structures for the complexes have been proposed.