SPECTROSCOPIC STUDIES OF ATOMIC OXYGEN USING GAS LASER TECHNIQUES

Laser actign on the 3p3 33 0 atomic oxygen triplet (0-1, 2-1, 1-1) at 8446A cannot occur at its fluorescence peaks. The laser levels, populated by molecular dissociation, have much broader velocity distributions than ground state atoms, which are at room temperature. Strong selective reabsorption of U. V. resonance radiation from the 330 level leads to increased population of those 3SO atoms with room temper-ature velocities. Thus, over a sizeable central portion of each 8446A component the population inversion is reversed, excluding the possibility 2) of laser oscillation there. The previously observed anomalous behavior, in which laser action occurs on the high-frequency side of the 2-1 fluo-rescence peak, follows from this effect and the fact that the 2-1 and 0-1 fine-structure components partially overlap. Estimates of the size of the effect are given, and applicability to other systems is discussed. At low pressures and favorable gain conditions a second, concurren