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Studies the line broadening and shifting of the vibrational branch in pure HD. Shifting and broadening coefficients; Rates of state-to-state rotational energy transfer.

Using a difference frequency spectrometer we have measured the Q(2) to Q(38) 20[sup 0]0←01[sup 1]0,Σ←Π transitions of carbon dioxide at 296 K and pressures up to 15 kPa. These low pressure spectra were analyzed using both the Voigt model, and an empirical line shape that blends together a hard collision model and a speed dependent Lorentzian profile. The broadening coefficients were obtained with an accuracy of 1% or better. The low density or first order low pressure line mixing parameters were also determined. We have compared both our measured low pressure line-mixing parameters and the complete band spectrum at high pressures with those predicted by a relaxation matrix calculated from an EPG fitting law. Spectra at the highest pressures were recorded using both the difference frequency spectrometer and an FTIR spectrometer, the temperature for the latter experiments being 303 K. The vibrational band intensity and linear pressure shift of the branch as a whole were also measured. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]