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The relaxation time and absorption and emission profiles of the 0.59 THz TO phonon resonance in a ε-GaSe single crystal were measured using terahertz free induction decay, observed directly as a sequence of decaying sinusoidal oscillations in the time-domain signal following single-cycle pulse excitation. The phonon line profile was also measured using frequency-domain transmission with the resolution of 0.25 GHz and was found to be Lorentzian. [ABSTRACT FROM AUTHOR]

Abstract: We present a simple algorithm for removing or reducing spurious oscillations in the THz spectra which result from secondary reflection peaks in samples or optical elements. The algorithm utilizes the fact that a THz time-domain trace containing secondary peaks can be represented as a convolution of the primary peak and two or more delta functions. The algorithm is applicable for samples which are sufficiently thick that the reflection peak does not overlap with the primary peak, and that do not have strong absorption or dispersion. [Copyright &y& Elsevier]

Photoluminescence at wavelengths between 600 and 660 nm was observed in Pr3+-doped GeS2-based glasses. The spectral profile of the 3P0→3H6 transition was found to be highly sensitive to the presence of oxide impurities in the glass. The main peak at 632 nm was identified with sulphide-dominated dopant sites, while the shoulder at 614 nm was attributed to oxide-dominated sites. Results demonstrate that the luminescence spectrum of Pr3+ at 610–635 nm reveals the presence and concentration of oxygen-rich sites in Pr3+-doped GeS2-doped glasses. The method is shown to be sensitive to concentrations of Ge&z.sbnd;O bonds down to 200 ppmw level. [Copyright &y& Elsevier]

Highlights: [•] Two novel methods used to determine renewable energy content and yield from mixed waste materials. [•] Biogenic content of waste components measured, along with proximate and ultimate analysis. [•] Determined values accurate to within 5% of actual values. [•] Key applications include renewable energy yield prior to combustion and classification of SRF. [ABSTRACT FROM AUTHOR]

Abstract: Terahertz time-domain spectroscopy measurements were made for vertically aligned multi-walled carbon nanotube (VACNT) films. We obtained the frequency dependent complex permittivity and conductivity (on the assumption that permeability μ =1) of several samples exhibiting Drude behaviour for lossy metals. The obtained material properties of VACNT films provide information for potential microwave and terahertz applications. [Copyright &y& Elsevier]

Abstract: We present excited state absorption (ESA) spectroscopy of Nd3+-activated fluoroaluminate glass. The ESA spectra were measured in the range from 550 to 1800nm by the continuous-wave pump-probe technique. Judd–Ofelt (JO) formalism was employed to interpret the results. The obtained intensity parameters and linewidths were used to simulate the ESA spectra, which were successfully compared with the experimental data. The calculated ESA spectra were also used to precisely assign previously observed upconverted emissions and to predict additional ones, which were experimentally verified. The presented upconverted luminescence spectrum contains several anti-Stokes emission lines at 355nm, 381nm, 412nm and 448nm, and is in good agreement with the calculations. [Copyright &y& Elsevier]

Abstract: We report on the upconverted luminescence in neodymium-activated fluoroaluminate glass obtained with 800nm diode laser excitation. Several anti-Stokes emissions: at 588, 607, 720 and 750nm are observed and appropriate transitions are assigned. For both latter emissions we observe strong dependence on temperature: the 720nm emission intensity decreases with temperature, whereas the 750nm emission increases. Interpretations are presented in terms of the influence of oxygen-affected sites on the radiationless transitions and multiphonon anti-Stokes excitation. The models provide reasonable fits to the experimental data. [Copyright &y& Elsevier]