4B2 - Pulsed and steady-state infrared emission studies of CO2laser systems

Transient and steady-state infrared emission at 2.5 to 15 μ from low-lying vibrational-rotational levels of CO
2
has been studied using a dc discharge. The time-dependent behaviors of several levels important for laser excitation and relaxation were examined following a pulsed discharge. The decays were, in general, different and were not simple exponentials. Relaxation of vibrational energy of CO
2
appears to occur by collisions involving vibration-vibration exchange between different vibrational modes and vibration-translation relaxation of the bending mode. The rate of transfer of vibrational excitation from N
2
to various vibrational modes of CO
2
was investigated as a function of CO
2
pressure. The addition of He reduced the emission from the lower laser levels with respect to that from the upper laser level and increased the nonradiative decay rate of the lower vibrational levels by CO
2
-He collisions. Under pulsed excitation, in addition to CO
2
laser action nearly coincident with the pulse, a weaker, delayed output was observed.