V. V. Nevdakh

Temperature Dependence of the Vibrational Relaxation Rate Constants of CO2 (0001) in Binary Mixtures

The rate constants of intramolecular intermode relaxation of the CO2 molecule (0001) in pure CO2 and in binary mixtures with He, Ar, H2, O2, N2, CO, NO, N2O, and H2O were measured in the temperature range 300–1000 K by means of a laser-induced luminescence method. It is shown that these relaxation rate constants K for all the gas mixtures investigated increase with increase in the gas temperature in this range; the most efficient in deactivation of the 0001 level are the collisions of CO2 molecules with H2O molecules; the mechanisms of relaxation of the 0001 level of CO2 and their channels depend not only on the temperature but also on the parameters of colliding particles; for each of the colliding partners of the CO2 molecules there is a certain temperature Tc above which the temperature dependence of K is coordinated with the Landau–Teller dependence, and, moreover, the simpler the structure of the colliding partner of the CO2 molecule, the higher the temperature Tc. Deviations from these dependences at temperatures T < Tc are attributed to the influence of intermolecular forces of attraction, change of relaxation channels, and formation of molecular clusters. For all the colliding partners of the CO2 molecules, the interaction radii are determined from the intermolecular potentials of interaction used in the theoretical model.

Collisional broadening of CO2 lines by N2O pressure

Carbon dioxide line broadening coefficients by N2O pressure, as well as their temperature exponents, were calculated for a wide range of rotational quantum numbers in the 0001–1000 band. A semiempiric method that is based on the semiclassical broadening theory was used. It showed good results in calculations of half-widths and shifts of lines by pressure for H2O-N2(O2), CO2-N2(O2), and O3-N2(O2) systems. The calculated collisional half-widths were compared with the measured data obtained with a frequency-stabilized tunable CO2 laser for 11 vibrational-rotational transitions with rotational quantum numbers of the lower state to 38 at room temperature and for three transitions R(10), R(22), and R(32) in the temperature interval of 300 ≤ T ≤ 700 K in the 0001–1000 band. The calculated and measured data are in a good agreement.

Study of the parameters of the collisionally broadened R22 absorption line of the 1000-0001 transition in CO2 molecules: I. Experiment

Unsaturated absorption coefficients in pure carbon dioxide at pressures of 1 and 100 Torr and in CO2-N2 and CO2-He binary mixtures at a pressure of 100 Torr have been measured in the temperature range of 296–700 K using a frequency-stabilized tunable CO2 laser. The collisional self-broadening coefficient, the relative coefficients of collisional broadening caused by N2 and He buffer gases, and their temperature dependences have been determined for the R22 absorption line of the 1000–0001 transition in CO2 molecules.

Diagnostics of a Vibrationally Equilibrium CO2-Containing Gas Mixture at Atmospheric Pressure

A technique is presented for determining the partial pressure and temperature of carbon dioxide in a vibrationally equilibrium gas mixture at atmospheric pressure from experimentally recorded spectra of the absorption coefficient of the lasing lines of a tunable CO2laser.

New operation regimes of a CO2 laser with intracavity saturable absorber

Abstract New operation regimes of a CO 2 laser with CH 3 OH vapour as intracavity saturable absorber have been realized experimentally. The time evolution of the laser output power may be interpreted by the heteroclinic orbits in the phase space around two, three and more fixed unstable points with intensities different from zero.

Multifrequency Diagnostics of a Vibrationally Equilibrium CO2-Containing Gas Mixture

We present a technique which makes it possible to simultaneously determine the temperature T and the partial pressure of carbon dioxide in a vibrationally equilibrium gas mixture at atmospheric pressure by using the experimentally measured spectral distribution of the absorption factor at the oscillation lines of a tunable CO2 laser. The technique developed can be employed for monitoring both the energy efficiency and the ecological purity of the processes of combustion of large amounts of hydrocarbon fuels accompanied by release to the atmosphere of combustion products containing carbon dioxide.

Collisional self-broadening coefficients and probabilities of spontaneous emission of the CO2 1000–0001 transition lines

Using a tunable frequency-stabilized CO2 laser, the pressure dependences of unsaturated absorption coefficients (AC) are measured in pure carbon dioxide in the pressure range from 5 to 30 Torr, where the spectral line shape is described by the Voigt profile. The absorption coefficients are measured in the centers of R(8), R(22), R(34), P(22), and P(36) spectral lines of the 1000–0001 transition in the temperature range 300–700 K. By means of the least-squares method, the inverse problem is solved for the system of equations for AC at different pressures in the temperature range under study. The self-broadening coefficients

On the temperature dependence of collisional linewidths of the 10{sup 0}0 - 00{sup 0}1 laser transition in the CO{sub 2} molecule

{\gamma _{C{O_2} - C{O_2}}}