A pumping mechanism has been found for the CO/sub 2/ gas laser which involves the transfer of electronic energy from O/sub 2/ (/sup 1/..sigma..g/sup +/) to CO/sub 2/, the oxygen dropping to the /sup 1/DELTA g state. This appears to pump vibrational states of CO/sub 2/ which are above the lasing state (001), and which most deactivate collisionally to (001) before the emission pulse. A pure rotational, diatonic OH laser has been discovered which is collisionally pumped from excited vibrational levels. Typical pure rotational lasing is observed between J levels energetically equivalent to the vibrational frequency. These outputs have been compared for different rare gas collisional partners and it has been found that the intensity passes through a maximum for partners of intermediate mass, Ne or Ar. The HCN laser of 337 ..mu..m has been found to be susceptible to chemical pumping by the reaction, CN + H/sub 2/ ..-->.. HCN + H. It has not shown any indication of possessing an advantage in power over the HCN-discharge laser. It has also been pumped optically by an ultraviolet flash. The intensity here, too, is limited, but the behavior of the output as a function of nonreactive diluents is of scientific …