Near single-line operation of a free burning CS2/O2/N2O flame laser with a nondispersive optical cavity

The CS2/O2/N2O flame laser was operated under conditions in which the spectral output is nearly single line. This transition is the P10-9 (17) of CO at 5.4265 microns, the same transition which was observed to oscillate in single line fashion by Hirose et al in an electrically initiated CO chemical laser. It is suggested that the unique behavior of this line may be due to its close proximity to a P branch transition in an adjacent band, namely the P9-8 (23) line, such that the gain profiles of the two lines overlap. Calculations suggest that, for this to be true at the conditions of these experiments, the separation of the line centers for this pair must be about 0.3 A or less. The P10-9 (17) transition was also found to be totally absent under certain conditions of high multiline power, particularly at low O2 and N2O flows. This may be due to absorption by a high band R branch transition at 5.4266 microns namely, the R15-16 (32) line.