Infrared absorption spectra of gaseous HD. I. Collisionhyphen;induced fundamental band of HD in the pure gas and HDndash;He mixtures at room temperature

摘要

The infrared absorption spectra of the fundamental band of HD in the pure gas for densities up to 50 amagat and in HDndash;He mixtures for different base densities of HD and a number of total gas densities up to 190 amagat have been studied at room temperature. The collisionhyphen;induced features of the band in the pure gas and in HDndash;He mixtures are similar to those previously observed for the spectra of H2and D2in the pure gases and in their binary mixtures with helium, respectively. In addition, the absorption profiles of the pure gas show the allowed sharpR1(1) transition due to the individual HD molecules. The binary absorption coefficients of the band derived from the measured integrated intensities are 2.32times;10minus;35and 0.94times;10minus;35cm6thinsp;sminus;1for pure HD and HDndash;He, respectively. An analysis of the profiles of the enhancement of absorption of the band in HDndash;He has been performed by assuming appropriate line shapes, and the three halfhyphen;width parameters, dgr;dand dgr;cof the overlap transitions and dgr;qof the quadrupolar transitions, are obtained. The halfhyphen;width dgr;cof the intercollisional interference dip of theQbranch increases with density rgr; of helium and fits to the equation dgr;c=argr; minus;brgr;2(aGt;b). This observation and the conclusions derived from it are similar to those obtained previously for H2ndash;He.