Effect of water vapor on spectrum broadening of CO₂

Using a high resolution continuous-wave mid-infrared difference frequency generation spectrometer and a long adjustable optical path White cell, water vapor pressure broadening coefficients for 22 transitions in the R branch and last 4 transitions in the P branch of the 10011←10002 band of CO2 has been detected at room temperature. The recorded lineshapes were fitted with Voigt line profile in order to determine the water vapor collisional broadening coefficients of 26 CO2 transitions from 2 422 cm-1 to 2 457 cm-1，the result shows that the water vapor collisional broadening coefficients are about 52% bigger than the dry air collisional broadening coefficients. The transmission of CO2 perturbed by dry and wet air(2.0 kPa water vapor) at the pressure of 0.1