"Synthesis and Optical Properties of Polystyrene Doped with DCM Thin Films "

"In the present work Polystyrene (PS) polymer doped with DCM laser dye thin films have been prepared on glass substrate using casting method. The final samples of PS doped with DCM thin films were treated with different annealing temperatures at (30, 40, 50, 60) oC. Optical absorption and transmission spectra of the prepared thin films were recorded using UV-VIS double beam spectrometer in the wavelength range from 190 to 1100 nm. The results shown that the allowed direct electronic transitions energy gap increased from 2.08 up to 2.25e.V as the temperature increasing from 30 to 60oC, whereas the allowed indirect electronic transition energy gap increase from 2.02 up to 2.17 eV as the temperature increase from 30 to 60oC. The effect of temperature on the optical properties such as Urbach’s energy, Refractive index, Extinction coefficient, Critical angle, Brewster angle, and Finesse coefficient of PS doped with DCM thin films also studied in this work.

The acceptors behavior in the Single and Double Doped Bi12TiO20

The absorption coefficient of Bi12TiO20:AlI, Bi12TiO20:AlII, Bi12SiO20:P and Bi12SiO20:Al+P single crystals is measured in the spectral region of Urbach’s rule (1.52 – 2.92 eV) at room temperature. The parameters of electron-phonon interaction, Urbach’s energy and the constants of Urbach’s rule are calculated. The behavior of the acceptors Al3+and P5+in Urbach’s rule region has been considered.

Compositional Dependence of Optical Absorption in Barium Oxychloride Borate Glasses

The present communication deals with some significant results pertaining to the optical absorption analysis of glasses in the compositional range of xBaCl2·(30–x)·BaO·68B2O3·2V2O5 (x = 0, 5, 7 and 10 mol%) prepared via convenient melt-quench route. The optical absorption data recorded in wavelength range of 200–800 nm is analyzed by means of Davis-Mott model to evaluate optical band gaps corresponding to direct and indirect transitions. The absorption tail is analyzed to obtain Urbach's energy. Behavioral change in optical band gap and Urbach's energy with changing chlorine concentrations is discussed to predict the structural changes governed in the glass matrix.

FTIR and UV-Vis-NIR Spectral Studies of Borotellurite Glass

A glass system based on composition of 80TeO2-(10-x) B2O3 -10PbO-xNd2O3, where 0.0mol% ≤ x ≥ 2.5mol% was successfully prepared by melt-quenching method. The structural and optical behavior of the Nd3+ doped borotellurite glasses are well studied by mean of their FTIR, XRD as well as UV-Vis -NIR spectroscopy. The XRD pattern obtained confirms the amorphous nature of the glass. Meanwhile, the infra-red absorption spectra of glass samples obtained are recorded using an FTIR spectrometer in the wave number ranging from 400 to 4000 cm-1. The bands observed were attributed to the different modes of vibrations of Te-O band. From the absorption spectral measurements, the value of optical band gap (Eopt) and the Urbach energy (ΔE) values were calculated with the results were then been discussed nor reported. Quantitative justification of these absorption bands shows that the values of the experimental wave number for most absorption bands are in agreement with the theoretical ones. Optical absorption spectra show that the absorption edge has a tail extending towards lower energies. In general, an increment or a decrement in Urbach’s energy can be considered to be due to a deformation of glass network.

OPTICAL AND SPECTROSCOPIC STUDIES OF Fe2O3-Bi2O3-B2O3:V2O5 GLASSES

The glasses of compositions x Fe 2 O 3⋅ (40 - x) Bi 2 O 3⋅60 B 2 O 3⋅2 V 2 O 5 have been prepared by the standard melt-quenching technique. Amorphous nature of these samples is ascertained by XRD patterns. The presence of BO 3 and BO 4 units is identified by IR spectra of glass samples. The absorption edge (λ cut-off ) shifts toward longer wavelengths with an increase in Fe 2 O 3 content in the glass matrix. The values of optical band gap energy for indirect allowed and forbidden transitions have been determined and it is found to decrease with increase in transition metal ions. The Urbach's energy is used to characterize the degree of disorder in amorphous solids.