Optical and structural characterization of iron oxide and cobalt oxide thin films at 800 nm

We report on optical and structural properties of α-Fe₂O₃ and Co₃O₄ thin films, grown by direct oxidation of pure metal films deposited on soda-lime glass. Structural characteristics and morphology of the films were investigated by X-ray diffraction, atomic force microscopy, and scanning electron microscopy. Linear optical absorption, and linear refraction as well as nonlinear optical properties were investigated. The third-order optical susceptibilities were measured applying the Thermally managed Z-scan technique using a Ti: sapphire laser (150 fs; 800 nm). The results obtained for the Co₃O₄ film were \( \text{Re} \chi^{\left( 3 \right)} \) = ?(5.7 ± 2.4) ×10^?9 esu and \( \text{Im} \chi^{(3)} \) = ?(1.8 ± 0.2) ×10^?8 esu while for the α-Fe₂O₃ film we determined \( \text{Re} \chi^{(3)} \) = +(6.6 ± 2.4) ×10^?10 esu and \( \text{Im} \chi^{(3)} \) = +(2.2 ± 0.4) ×10^?10 esu.     

Dielectric Measurements as a Function of Temperature of Sodium‐Lithium Phosphate Glasses Evaluated at 10 MHz and 9 GHz

Dielectric constant measurements can be performed at temperatures greater than room temperature; some techniques are shown in this work. The dielectric constant of phosphate glasses, measured in the X‐band microwave range, was determined using a microwave setup assembled to measure the shift in the standing wave pattern produced by the insertion of the sample inside the waveguide. The glass system 50P₂O₅ · 25Li₂O · 25Na₂O was chosen in this work due to its lower melting point and lower transition temperature (T_g) values. The dielectric constant of the glass studied in this work increases in the temperature range 25–330°C, as shown by the results at radio and microwave frequencies. The method of standing wave shift was applied, and it is shown to be a useful tool to estimate the T_g of glasses. This assumption was confirmed by differential thermal analysis technique. Measurements were compared to that at 10 MHz by impedancimetric methods.     

Dual-broadband rotational CARS modelling of nitrogen at pressures up to 9 MPa. I. Inter-branch interference effect

An improved model for pure rotational coherent anti-Stokes Raman scattering (CARS) has been developed for the dual-broadband approach. This model takes into account the fact that coherent anti-Stokes as well as Stokes radiation are generated simultaneously, and these two branches overlap and interact at high pressures giving rise to an inter-branch interference effect. In combustion studies, the anti-Stokes branch is used to determine temperature and concentrations of key species, of which nitrogen is the most widely used, and we have found that the interference effect on the anti-Stokes side is of such magnitude that it clearly needs to be taken into account at pressures of a few MPa. The necessary modifications to the total third-order susceptibility are presented and a derivation of the convolution integral for a finite-bandwidth pump source is given. Received: 18 February 2002 / Revised version: 9 July 2002 / Published online: 22 November 2002 RID="*" ID="*"Corresponding author. Fax: +46-46/2224542, E-mail: mikael.afzelius@forbrf.lth.se     

Nanometric size control and treatment of historic paper manuscript and prints with laser light at 157 nm

Laser cleaning of historic paper infected by foxing is far more effective at 157 nm than in other laser wavelengths because at 157 nm localized photo-dissociation of organic matter is taking place at low laser energy. In addition spatial control over exposed areas with resolution better than 100 nm is possible at this wavelength. In order to optimize the methods of laser cleaning of historic paper, foxing ablation experiments at 157 nm indicate that infected paper areas can be removed with controllable spatial resolution in the nanometer scale. In addition foxing samples were investigated by scanning electron microscopy and X-ray analysis. It was found that biological activity was present on paper areas containing traces of iron. PACS  87.50.Hj; 42.62.-b; 87.15.Mi     

On the contribution of interference of electromagnetic and chromomagnetic dipole operators in the $$ \bar B $$ → Xsγ decay at O(αs2)

The contribution of c-quark loops into the interference of the electromagnetic and chromomagnetic dipole operators in the \(\bar B\) → X _s γ decay is calculated to O(α _s ² ) within the framework of the Standard Model (SM). Several new calculation techniques, such as Laporta’s automated algorithm, the second order decomposition method, and Mellin-Barnes representation, have been used.