Absolute direct excitation cross sections from the neutral ground state have been measured for upper levels of the strongest laser transitions in Ar II to within errors of ^20 %. Reasonable agreement is obtained with calculated values of these cross sections based on the sudden' approximation made by Koozekanani with Hartree-Fock wave functions and intermediate coupling.

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Laser action at 16 μ has been obtained between the (02°0) and (0110) levels as well as between the (10°0) and (0110) levels at 14 μ. A 9- or 10-μ saturating pulse equilibrates the (001) level with either the (02°0) or (10°0) level and creates the transient 14- or 16-μ inversion. Extraction efficiencies of 20% have been achieved on a single pulse. Repetition frequencies of 200 Hz have been achieved using a single Q-switched cavity.

The performance of the 14- and 16-μm CO2 lasers produced in the electric discharge gasdynamic laser has been significantly improved by the addition of a small percentage of H2 to deactivate the (0110) level. This addition tripled the pulsed output of the laser, and 45 μJ at 14 μm and 25 μJ at 16 μm were observed. cw oscillation was achieved for the first time, with output powers of 0.6 and 0.9 W, respectively. The effect of collisional processes in limiting the CO2 density is discussed.