A.S. Dudaryonok

Influence of isotopic substitution in the absorbing molecule on the self-broadening coefficients of carbon dioxide spectral lines

The dipole moment effect, which occurs due to isotopic substitution of one oxygen atom in the absorbing molecule, on the collisional half-width of rotational-vibrational lines in the ν3 band in the case of perturbation by the main isotopologue 16O12C16O is investigated. Self-broadening coefficients of lines of the carbon dioxide isotopologues are calculated by two methods: semi-empirical and semi-classical. Weak but noticeable variations in the line halfwidths for different isotopologues are revealed when using both methods.

The Average Energy Difference Method for Calculation of Line Broadening of Asymmetric Tops

A new method for estimation of broadening coefficients of vibrational-rotational lines of asymmetric tops is presented. The method allows finding line widths on the basis of a few empiric data without complicated calculations. Based on the analysis of experimental data, the dependence of the average energy difference on vibrational quantum numbers is found. The approach has been tested by the example of calculation of line broadening of asymmetric tops H2O and HDO. Calculated parameters of line profiles were compared with experimental data in different absorption bands.

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.

Calculation of line parameters of the ν 3 band of monodeuterated methane: Nitrogen broadening

Halfwidths and shifts of CH3D lines are calculated for the case of nitrogen broadening. The calculations are performed for room temperature (296 K) for vibrational–rotational lines in the ν3 parallel band, with the rotational quantum numbers varying in the ranges of 0 ≤ J ≤ 70 and 0 ≤ K ≤ 20. For each line, the temperature-dependence characteristics are calculated in the range of 200–400 K recommended for the HITRAN database. The calculations are carried out using a semiempirical method with a correction factor the parameters of which are adjusted on a number of experimental values.