High resolution CARS spectrum and analysis of the v1 band Q-branch of carbon dioxide

High resolution coherent anti-Stokes Raman spectroscopy (CARS) has been applied to the study of the Q-branch of the fundamental vibrational v 1 band of CO 2 in the Fermi resonance region near 1285·5 cm -1 . Thanks to the use of high spectral quality (linewidth = 6 MHz) injection-locked flashlamp-pumped dye lasers, it was possible to resolve this band for the first time. The spectrum was recorded at a pressure of 5 kPa (37·5 Torr) at room temperature. We measured the line positions and collisional widths for the transitions with J values from 8 to 38. Our experimental line positions are in excellent agreement with those derived from molecular constants given on the literature. The observed linewidths agree for most of the lines within 5 per cent with the values calculated from a recently developed model.