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Recently, experimental electron impact widths and ion broadening parameters of isolated Kr I lines were reported. In addition, the contribution of Kr II and Kr III ion dynamics to Kr I line widths is determined. Here, on the basis of the critical evaluation of the plasma source, the deconvolution procedure and earlier results by the same authors, possible causes for erroneous line shape recordings and their interpretation, are discussed. To demonstrate the experimental difficulties in the procedure used for Stark broadening parameter measurements, an additional experiment is performed and profiles of plasma-broadened lines are generated. All our new results and the analysis of the plasma source, experimental procedure and reported data of Kr I lines indicate that certain aspects of earlier work need further investigation.

A pulsed low-pressure capillary discharge operated in neon, helium and hydrogen gas mixture was used as the source of a high-density plasma with predominantly protons as ions for the measurement of the spectral line profiles of 13 isolated Ne I lines. An electron density of 4.8 × 1022m?3with an estimated uncertainty of 10% was determined from the profiles of three He I lines, while an electron temperature of 33 000 K, with an uncertainty of 12%, was measured using the relative intensities of O II impurity lines. The experimental widths of symmetric Ne I profiles are compared with data of two semiclassical calculations using quasi-static and ion impact approximations. The average ratio of measured to theoretical line widths is approximately the same for both theoretical approaches, showing good agreement in either case. This agreement with both theories must be considered, however, to be accidental, for the following reason. In one theory, the electron impact widths are relatively larger with small quasi-static ion contribution, while the other approach produces relatively smaller electron and larger ion impact widths. The asymmetric He I line profiles prove that the semiclassical theoretical approach with quasi-static ion approximation describes better the experimental Stark profiles of He I and Ne I lines. Contrary to the recently reported experimental Ne I line shapes, all studied profiles are symmetric within experimental uncertainty. Possible causes for the line asymmetry and discrepancy of Stark widths with data of this experiment are traced to the plasma source inhomogeneity and plasma diagnostics. Good agreement with several other experiments is detected.

The solution to the problem of diffraction of parallel and perpendicularly polarized waves from an echelette grating is discussed with special emphasis on diffraction anomalies. Two new kinds of anomalies are described. The first kind occurs when the phase change of the incident wave over the groove is equal to a multiple of π, while the second kind occurs when this phase change is equal to an odd multiple of π/2. The first kind can coincide with a double Rayleigh anomaly, which for a perpendicularly polarized wave then results in an amplified anomaly. If, additionally, one of the grazing orders in the double Rayleigh anomaly is +1, a resonant-type anomaly results. This resonance anomaly could be utilized in a laser cavity or for the purpose of spectral or spatial filtering.

Laser optoacoustic spectroscopy technique has been used to measure the absorption coefficients of eight gas pollutants at CO2 laser wavelengths between 9.2 μm and 10.8 μm. All measurements were performed with pollutant at a low pressure in the presence of 1 atm of nitrogen. For outdoor longoptical path monitoring of air pollution paier of lines (detection and reference line) have been selected.

Laser optoacoustic spectroscopy technique has been employed to measure the absorption coefficients of seven gas pollutants at CO2 laser wavelengths between 9.2 μm and 10.8 μ. All measurements were performed with the pollutant at a low pressure in the presence of 1 atm of nitrogen. Out of these seven gases sub-ppm quantities of ethylene, ammonia, freon 12, thrichlorethylene, ethanol and toluene can be detected with the same apparatus.