R-branch emission from a cw CO chemical laser

Abstract

The effect of adding vibrationally ``cold'' CO to a CO chemical laser is shown to increase the inversion ratios on the vibration levels of the chemically formed molecules. This fact is demonstrated experimentally by the observation of R-branch emission, reported here for the first time in any cw flow and mixing chemical laser. R-branch lines can be seen experimentally only with the addition of cold CO, and then only with a frequency-selective optical cavity. Theoretical calculations indicate that the total inversions predicted from the known distribution of the O + CS pumping reaction are rapidly depleted by vibration-vibration (VV) relaxation. The collisional VV exchanges with cold CO are shown to increase the vibrational inversion ratios to the extent that total inversion is observable in experimental devices limited by mixing and reaction times that are not fast compared with VV equilibration.