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Abstract: We have studied a set of GRBs detected by HETE-2 satellite with special focus on low-energy part of the spectrum. Results of data reduction procedures of different members of the HETE collaboration were combined with other publicly available information creating a concise catalogue. A more detailed analysis of lightcurves of the prompt emission was performed using data from FREGATE instrument. [Copyright &y& Elsevier]

We report an investigation of the optical and structural properties of wurtzite phase Al x Ga 1− x N/AlN structure grown on Si(111) within the compositional range of 0 ≤ x ≤ 1. The study focuses on providing essential physical quantities for the fabrication process control, namely the composition dependence of phonon mode energy and refractive index. Three complementary techniques, infrared ellipsometry, Raman spectroscopy and X-ray diffraction, have been used to minimize uncertainties in our analysis. Based on the high quality and nearly strain-free Al x Ga 1− x N/AlN double layer samples, we determined the calibration curve for the A 1 (LO) phonon mode. We have also constructed the ellipsometry model which uses a-priori knowledge of experimentally measured A 1 (TO) phonon mode frequencies. From the best model fit to the collected ellipsometry spectra of the entire sample series, we obtained the anisotropic refractive indices of the Al x Ga 1− x N alloys with a very satisfactory accuracy. [ABSTRACT FROM AUTHOR]