E. N. Chesnokov

Terahertz free-electron laser radiation to determine water concentration in flames

The possibility of measuring the concentration of H2O molecules in flames based on the absorption of terahertz free-electron laser radiation was studied. These measurements were performed using the 177.32 cm−1 absorption line in the rotational spectrum of H2O. This line has a low intensity at room temperature, and at about 1000 K, its intensity is comparable to that of the strongest lines. The temperature dependence of the radiation absorption coefficient at a frequency of 77.32 cm−1 was studied theoretically and experimentally. It is shown that the method can be used for measurements in a sooty C2H4/O2/Ar flame, which strongly scatters visible and UV radiation.

IR absorption band contours of methyltrifluorosilane : Calculation and comparison with experiment

The IR spectrum of methyltrifluorosilane is measured in the range 220–3500 cm−1. Both the equilibrium configuration of the molecule and its vibrational frequencies are calculated quantum chemically. Using the rotational and Coriolis constants obtained in these calculations, the contours of the rotational bands in the IR spectrum are numerically modeled. A comparison between the calculated and the experimental spectra made it possible to refine the frequencies of the fundamental vibrations of the molecule and determine the isotope shifts of the fundamental Si-F vibration with respect to the stable isotopes of silicon.

15N isotope-selective infrared multiphoton dissociation of nitromethane by a free electron laser

Successful experiments on the isotope-selective infrared multiphoton dissociation (IR MPD) of nitromethane molecules in the region of stretching vibrations of the NO2 group have been performed for the first time under IR free electron laser (FEL) irradiation in a mixture with the natural content of the15N isotope of 0.4%. The content of the15N isotope in the products of NO dissociation varies within 0.1–1.6% as a function of the laser radiation frequency.

Isotope-selective multiphoton dissociation of chloromethyltrifluorosilane molecules (CH3ClSiF3) induced by pulsed CO2 laser radiation

ISSN 0012-5016, Doklady Physical Chemistry, 2007, Vol. 415, Part 2, pp. 221–224.

Amplification due to a lasing transition in CO2 molecules excited in the course of an SiH4 chlorination chain reaction

An experimental study was made of the amplification due to a lasing transition in a CO2 molecule excited as a result of energy transfer from excited SiH3Cl molecules formed in the course of a SiH4 + Cl2 chain reaction initiated by third-harmonic radiation from a neodymium laser. Investigations were made of dependences of the gain on the mixture pressure and composition. Chemical energy from the SiH4 chlorination reaction was efficiently converted to laser radiation energy.