Spectroscopic Ellipsometry Study on Surface Roughness and Optical Property of AZO Films Prepared by Direct-Current Magnetron Reactive Sputtering Method

All as-deposited AZO films by direct current magnetron reactive sputtering （DC-MS） exhibit ZnO characteristic （002） and （103） diffraction peaks. Especially, AZO films prepared at 200℃ show a strongest （002） c-axis pref- erential orientation due to the minimum stress along the （002） orientation. The results show that larger stress easily induces a rougher surface. The film real and imaginary parts of dielectric constants show a sharp changes near the optical absorption edge due to the interband direct transition. The film blue and red shifts of the optical absorption edge can be explained in terms of the change of Free-electron concentration in as-deposited AZO films.     

Photoluminescence properties of the ZnO-CdO-TeO2 system doped with the Tband Yb ions

ZnO-CdO-TeO₂ was employed as a host of Tb³⁺ and Yb³⁺ ions. The matrix doped with Tb³⁺ presents a crystalline/amorphous structure, while the same matrix shows an amorphous structure when it is doped with Yb³⁺. Optical absorption spectra, measured by using photoacoustic (PA) spectroscopy, allowed to determine the band gap, which is localized in the range 3.47-3.60 eV. Both kinds of ions Tb³⁺ and Yb³⁺ in the ZnO-CdO-TeO₂ matrix show emissions that are characteristic of such ions. For Tb³⁺ the signals were allocated in 548, 586, 622 nm, respectively, while for Yb³⁺ only one signal was registered at 1000 nm.     

Characterization of various aluminium oxide layers by means of spectroscopic ellipsometry

This paper reports the characterization of both barrier type and porous type anodic oxide films on aluminium by means of spectroscopic ellipsometry (SE). In order to show the capabilities of the technique for quantitative determination of the layer characteristics, results based on ellipsometric data are correlated with complementary information from the analytical techniques transmission electron microscopy (TEM) and Auger electron spectroscopy (AES). It is concluded that ellipsometry yields an accurate characterization for the thicknesses and the interfacial properties of both the barrier layer and the porous layer. The porosity of the porous layer, determined with SE, is found to be in good agreement with the results obtained from TEM.     

Pinched inlet gravitational split-flow thin fractionation of airborne particles and analysis of size dependent level of PCDD/Fs

Fine particles in air have a direct influence on human health because they carry toxic chemicals that can be deposited in the human lung when inhaled. Thus, particle size distribution and size dependent level of contamination of the airborne particles are important parameters for the study and assessment of environmental pollution. In this study, gravitational split-flow thin (SPLITT) fractionation (or GSF), a semi-preparative scale separation technique for particles, was applied for the continuous size sorting of airborne particles collected in urban area. About 2.0 g of airborne particles was fractionated into four different size intervals (<1.5, 1.5-2.5, 2.5-5.0, and >5.0 microm), and the collected fractions were examined by electron microscopy for particle size distribution and analyzed for the size dependent levels of polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs). It was found that more than 60% of particles including dissolved matters in weight were smaller than 5.0 microm and they contained more than 86% of the total PCDD/Fs amount in airborne particles.     

Differences in retention of dioxin-like compounds and organochlorinated insecticides on an immunochromatographic column. Interpretation and applicability

The retention of organochlorinated compounds on an immunochromatographic column is studied. The compounds considered are usually found together in real samples of environmental concern, and include chlorinated biphenyls, chlorinated dibenzo-p-dioxins, chlorinated dibenzofurans, and organochlorinated insecticides. The different retention observed for different compounds is interpreted in light of the structural similarities of the compound studied with that used as a hapten to raise the antibodies employed as ligands in the immunochromatographic column. Differences in retention of the organochlorinated compounds on the immunocolumn make it possible to fractionate them. Mixtures of phosphate buffer solution and ACN in different ratios were used as desorption agents. Depending on the percentage of ACN employed, different fractionations of the organochlorinated compounds are obtained. The use of 20% ACN allows fractionation of most insecticides from chlorinated biphenyls, dioxins, and furans. Besides, chlorinated biphenyls of different chlorination degree can be separated. Moreover, pentachlorinated dioxins and pentachlorinated furans are separated from hexachlorinated biphenyls. Fractionation is of critical importance from a practical point of view, as it avoids some of the interferences that otherwise take place during the subsequent gas chromatography/mass spectrometry (GC/MS) analysis of these compounds. In this way, immunochromatography makes it possible to perform in a single step all the processes (extraction, clean-up, concentration, and fractionation) that are needed prior to the GC/MS analysis of these analytes in aqueous samples. An additional advantage of this method is the reusability of the immunoaffinity chromatography column for more than 500 times.     

The formation of glassy alloys by irradiation with intense proton beams

Using a 50 ns pulse of an intense proton beam 1.5 J cm^–2 of energy was deposited in a 1 m thick surface layer of glass forming alloys. In Fe₈₀B₂₀, the formation of a glassy surface layer of 1.9 m thickness was observed by x-ray diffraction. Etching experiments performed with alloys containing phosphorus yielded similar results. Applying a mask technique amorphous and crystalline zones were structured with a resolution of better than 2 m.On leave from Central Electronics Engineering Research Institute, Pilani, Rajasthan, India     

Regularization in ellipsometry

The continuous variation of the refractive index with the depth in the vicinity of surfaces can be determined by ellipsometry without destroying the object of measurements. The presented method does not impress any given structure to the profile and is applicable to just the range of layer thicknesses interesting to optics (about /4 to /2). The theoretical approach to interpret the measured data leads to an integral equation that is numerically inverted by regularization to filter out the destabilizing effects of measurement errors. The regularizing operator and regularization parameter responsible for this filtering are founded on physical arguments and experiment, respectively. These results can be transferred to other regularization problems based on quantities related to volume (e.g. density, temperature).     

Fluorinated silica glass ablated with ArF excimer laser at low fluence

Amorphous SiO₂ (a-SiO₂) was formed by liquid-phase deposition (LPD) at room temperature. As a result of one shot of ArF excimer laser irradiation, LPD-formed a-SiO₂ shows a threshold fluence for ablation of below than 200 mJ/cm², which is much lower than the threshold fluence (∼1 J/cm²) of a-SiO₂ formed by thermal oxidation of silicon. Raman scattering spectroscopy revealed that two sharp lines at 495 cm⁻¹ and 606 cm⁻¹, respectively, labeled D₁ and D₂, had disappeared, and the main band at 430 cm⁻¹ was sharpened in LPD-formed a-SiO₂. It is presumed that the fluorine broke the silica network, relaxing the Si-O-Si bond angle and dramatically reducing the threshold energy for ablation of a-SiO₂.     

Effect of ZnO and Bi2O3 addition on linear and non-linear optical properties of tellurite glasses

Glasses in the system TeO₂-Bi₂O₃-ZnO were studied with respect to their linear refractive indices and optical absorption in the UV-vis range. The third order non-linear refractive indices were measured using degenerated four wave mixing (DFWM). The optical Kerr susceptibilities calculated hereof were in the range from 5.49 to 6.58 × 10⁻¹³ esu and hence 34-41 times larger than that of fused SiO₂. They are roughly proportional to values theoretically calculated by the theory of Lines.     

Use of FTIR reflectance spectroscopy to monitor corrosion mechanisms on glass surfaces

Fourier transform infrared (FTIR) reflectance spectroscopy was used to monitor corrosion mechanisms on the surface of lithium disilicate (Li₂O-2SiO₂) glass samples exposed to an aqueous solution for short times. The traditional mechanisms of glass corrosion were observed but a spectral feature was resolved that was previously unreported. This feature consisted of a peak suspected to result partially from a silanol (Si-OH) vibration in the region 800-1050 cm⁻¹ that shifted and reappeared in a cyclic fashion throughout the corrosion process. The behavior of this peak tends to suggest that the creation and condensation of Si-OH groups is the reaction responsible for causing the shift of the main Si-O-Si and Si-O⁻ peaks, a phenomenon which has previously lacked a detailed explanation.