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Time- and spatially-resolved optical emission spectroscopy was performed to characterize the plasma produced in a hybrid magnetron-sputtering-laser deposition system, which is used for TiC or SiC thin films preparation. A graphite target was ablated by a KrF excimer laser (λ=248 nm,τ=20 ns) and either Ti or Si targets were used for DC magnetron sputtering in argon ambient. Spectra were measured in the range 250–850 nm. The evolution of the spectra with varying magnetron powers (0–100 W) and argon pressures (0.3–10 Pa) was studied. Spectra of the plasmas produced by a) the magnetron alone, b) the ablation laser alone, and c) the magnetron and the ablation laser together, were recorded. Spectra (a) were dominated by Ar atoms and Ar+ ions. Emission lines of Ti and Si were detected, when Ti target and Si target was used, respectively. Spectra (b) revealed emission of C, C+, C2, Ar, Ar+. Spectra (c) showed presence of all previously mentioned species and further of Ti+ ions emission was detected.

The formation and decay of carbon and nitrogen atoms, CN radicals and C2 molecules were monitored using spatial- and time-resolved emission spectroscopy in a plasma plume formed during laser ablation of a graphite target in nitrogen atmosphere. A simple exponential model was used to explain the effect of the individual chemical reactions and plasma dynamics on the measured kinetic characteristics. The succession of emissions C N CN was observed in the time-resolved spectra, supporting the suggestion that the CN radical is formed mainly by the direct reaction C + N CN or C2 + N2 2CN. The formation of CN radical was enhanced by the additional generation of atomic nitrogen through the RF discharge. (© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

CO 2 laser photoacoustic spectroscopy was used for quantitative analysis of a multicomponent gaseous mixture of pollutants with similar chemical structures (toluene, ortho -, para - and meta -xylenes) in trace concentrations (50–700 ppm). The agreement with the results of gravimetric measurements was better than 5% in most cases. The following detection limits were found for this method in the given arrangement: 3.57±0.04 ppm for toluene, 1.82±0.02 ppm for o -xylene, 1.00±0.01 ppm for p -xylene and 2.86±0.04 ppm for m -xylene. Determination of the concentration using the classical least squares method was compared with a method based on the principle of calculation of the lowest component entropy. While the least squares method yielded the most selective analysis when four lines were used for four-components mixture, introduction of the component entropy yielded an increase in the selectivity level by measurement of six lines.

Absolute line intensities of sixteen rovibrational transitions in the ν4 band of 14NH3 were measured around 1800 cm−1 using a tunable diode laser spectrometer with a sweep modulation of the laser frequency. Individual laser scans over the line region were recorded to disk storage separately and the spectrum accumulation was performed off-line using a computer to reduce a significant line broadening because of a lower accuracy of the hardware on-line accumulation. From integrated absorption coefficients obtained by the numerical analysis of the measured line profile, the effective transition moments of individual rovibrational lines were derived. Using the second order perturbation theory of the transition moment of rovibrational transitions of the symmetric top molecules, the effective vibrational transition moments for the ν4 fundamental band of 14NH3 were estimated.

The performance of the InAsSbP/InAs lasers for absorption spectroscopy of ammonia at 3370–3660 cm−1 was first shown. These continuous wave lasers based on the III–V semiconductor are alternative to a widespread utilised Pb-salt device and were first investigated in closed-cycle He-cryostat at temperatures of 32–85 K. The spectral and tuning characteristics of the laser were considered versus both heatsink temperatures and drive currents in viewpoint of applications in molecular laser spectroscopy, with best device performance being found at 45–65 K. The preliminary experiments to record spectra of the ammonia absorption with the diode were undertaken.

The article reports the results of different methods of modelling releases and dispersion of dangerous gases or vapours in cases of major accidents from road and rail transportation in urban zones. Transport accidents of dangerous substances are increasingly frequent and can cause serious injuries in densely inhabited areas or pollution of the environment. For quantitative risk assessment and mitigation planning, consequence modelling is necessary. The modelling of dangerous substance dispersion by standard methods does not fully represent the behaviour of toxic or flammable clouds in obstructed areas such as street canyons. Therefore the predictions from common software packages as ALOHA, EFFECTS, TerEx should be augmented with computational fluid dynamics (CFD) models or physical modelling in aerodynamic tunnels, and further studies are planned to do this. The goal of this article is to present the results of the first approach of modelling using these standard methods and to demonstrate the importance of the next development stage in the area of transport accident modelling of releases and dispersions of dangerous substances in urban zones in cases of major accident or terrorist attacks.

Properties of the plasma plume produced on a bismuth (Bi) target irradiated by a focused extreme-ultraviolet (XUV) capillary-discharge laser beam were investigated. Langmuir probes were used in both single- and double-probe arrangements to determine the electron temperature and the electron density, providing values of 1–3 eV and ∼1013–1014 m−3, respectively. Although the temperatures seem to be comparable with values obtained in ablation plasmas produced by conventional, long-wavelength lasers, the density is significantly lower. This finding indicates that the desorption-like phenomena are responsible for the plume formation rather than the ablation processes. A very thin Bi film was prepared on an MgO substrate by pulsed XUV laser deposition. The non-uniform, sub-monolayer character of the deposited bismuth film confirms the Langmuir probe's observation of the desorption-like erosion induced by the XUV laser on the primary Bi target.