The paper reports on experimental studies concerning the absorption spectra of molecular iodine and its − IO 3 , I − , − I 3 anions in the spectral band of 180-600 nm. Values of the absorption cross-sections of the above mentioned substances have been measured, and relations of absorption coefficients to concentrations have been studied. The results obtained demonstrate that the spectral band under consideration is likely to be successfully used for simultaneous real-time detection of substances containing iodine with an absorption method using laser emission sources in the UV and visible light spectral bands.

This study reports on the use of Kalman’s method for filtering an experimental signal to improve the accuracy of a 13С16О2 measurement in the exhaled human breath using tunable diode laser absorption spectroscopy with a semiconductor diode laser tunable near to a wavelength of 2 µm. It is shown that Kalman’s filtration allows a 5-fold increase in the detection accuracy of 13СО2.

The state-to-state collisional data on vibration-vibration and vibration-translation/rotation energy exchanged in N2(v)-N2(v') collisions recently obtained from accurate ab initio semiclassical calculations have been used to analyze the data measured in nitrogen under two different plasma conditions. In particular, the vibrational distribution function and the time-evolution of the gas temperature measured under post-discharge and glow discharge conditions, respectively, have been calculated and compared with the experimental observations. The theoretical analysis and the related results, generally in very good agreement with the experimental data, provide insight into the various energy-exchange mechanisms that lie behind the macroscopic behaviors of the nitrogen plasmas. In particular, the role played by the vibrationally excited nitrogen molecules in the gas kinetics is pointed out, as well as the importance of nitrogen atom production in the long time scales of the glow discharge.

Extensive semiclassical calculations have been performed regarding the generation of accurate collision data for single-and multi-quantum vibrational state-selected V-V exchanges in N 2 (v)-N 2 (u) and N 2 (v)-CO(u) collisions over a wide range of vibrational quantum numbers (v, u) and gas temperatures. This highly accurate database is also used to test the applicability of simplified analytical approximations frequently used in vibrational kinetic modeling to calculate large sets of state-to-state V-V rate constants in diatom-diatom collisions. The semiclassical calculations clearly show that the long-range attractive branch of the interaction potential cannot be neglected, even for the N 2 -N 2 system. Therefore, new analytical approximations for V-V exchanges for the two collision systems are proposed which agree very well with the semiclassical rates. The ab initio data, together with that obtained from the newly proposed analytical formula, constitute an accurate database that can be used with confidence in the vibrational kinetic modeling of N 2 and CO-based gases and plasmas over a wide temperature range, from thermal to hyper-thermal gas temperatures.

A novel method for noninvasive on-line diagnostics of gastrointestinal oncological diseases using a diode laser in the 4860-4880 cm −1 frequency range is proposed. The method is based on measuring the concentration of 13 С during expiration. The accuracy of the method allows performing early diagnostics of diseases.

No abstract

This letter details the development of an on-line control method for carbon dioxide molecules of various isotopes contained in gaseous media on the basis of a tunable diode laser operating in the 4860–4880 cm−1 range. It shows that the sensitivity of 13С registering may amount to ~1012 cm−3.

No abstract