Knowledge Bank

Water vapor and carbon dioxide absorption spectra have been measured in the $4.7-5.0\mu m$ Spectral region using tunable laser diodes. Strengths, self and air broadened widths and shapes in the $\nu 2,\nu 1-\nu 2$ and $\nu 3-\nu 2$ bands of water vapor and the $(1110\leftarrow 0000)1,(1220\leftarrow 0110)1$, and $(2000\leftarrow 0110)1$ bands of carbon dioxide have been investigated. These studies have been done under contract using the facilities at the U.S. Army Atmospheric Sciences Laboratory at White Sands. The scanning diode instrument used in the investigation is the A.D. Little Tuned Diode Laser Spectrometer Model TDLS-II. Folded absorption paths up to 100 meters in length wore measured using a white cell having a two meter physical length. Measured strengths and widths have been compared with values listed in the latest Air Force Geophysics Laboratory (AFGL) data $compilation1$ The comparison ranges from very good agreement to as much as a factor of two disagreement. Low pressure line shapes have been compared with calculated Voigt profiles, using the measured line strengths and widths for selected lines, and a comparison with super-Lorentz shapes postulated for water vapor absorption lines in this spectral and in the $2.7\mu m$ $band4$ is made.