[en] Based on the experimental features of the CO₂ laser Stark modulation process, a new method of estimation of the Stark tuning constant is presented, with special references to slightly asymmetric top molecules. A good agreement between our result and that obtained by other methods is found. (author)

[en] Using a frequency stabilized CO₂ laser, the absorption coefficients of methyl iodide were measured, for more than 40 lines of the P and R branches in the 10.4μm and 9.4μm bands of CO₂. The Stark modulation in CH₃I was studied vs. pressure and applied electric field. The percentage modulation for the P(14) line has a maximum in the pressure range 16-20 torr and increases almost linearly with the Stark voltage (m = -2.7% at 4 kV/cm and 24 torr). We found that three new lines of the CO₂ laser can be modulated by CH₃I, namely P(18), P(22) and P(24), but with a smaller percentage modulation than that for the P(14) line. (author)

[en] This study was conducted with the aim of testing the hypothesis that raspberry and strawberry fruits from nonorganic farming release more ethylene gas compounds compared to organic ones. At the same time, the experiments focused on evaluation of the potential and capabilities of the laser photoacoustic spectroscopy (LPAS) method in the assessment of fruit quality related to the effects of nitrogen. Ethylene gas can be harmful and carcinogenic, because it can accelerate the natural ripening process of physiologically mature fruits and makes the fruits more consistent in size. With the advantages of LPAS, we demonstrate that the concentration of ethylene from nonorganic raspberry and strawberry fruits is greater than from organic ones. (paper)

[en] Stark effect in 1.1 difluorethane was studied and the absorption coefficient and modulation index for the CO₂P(24) line is presented. The behaviour of the absorption shows the possibility for Stark stabilization of the CO₂ laser on the P(24) line, with an effective tuning range. (author)

[en] In recent years there has been a large increase in the areas related to developments in the prevention of diseases, especially in explaining the role of oxidative stress. Lipid peroxidation and oxidative stress contributes to morbidity in hemodialysis (HD) patients. It is therefore relevant to analyze the impact of oxidative stress and its related species (ethylene) immediately after dialysis treatment in order to prevent trauma in the renal failure of elderly patients. In this paper we describe recent progress in laser photoacoustic spectroscopy detection of ethylene in renal failure patients. We have found that HD treatment increases ethylene concentration in the exhaled breath of elderly patients and may intensify oxidative stress. (paper)