Tunable Diode Laser High Resolution Spectroscopic Measurements of the nu(2) Vibration of Carbon Dioxide.

A tunable diode laser spectrometer was used for high resolution measurements on the Q-branch of the nu(2) vibration of carbon dioxide. The infrared source was a current tuned Pb(0.936)Sn(0.064)Se diode laser. A 1-m gas cell was designed to allow variation of temperature (200-300 K) at 1-50 torr of 320 ppm mixtures in nitrogen. Owing to the narrow linewidth of the diode laser, true line shapes may now be measured well into the Doppler region. Line shapes and intensities of several rotational lines (J </= 34) have been measured as a function of pressure and temperature. Initial measurements tend to confirm the theoretical predictions of Drayson as to relative line positions, but show linewidths higher than predicted by Yamamoto et al. The line strengths, at low temperatures, appear to be about 12% greater than those predicted by Drayson.