Rotational population transfer in HF

Population transfer in HF by both collisional and radiative processes was measured by ir-laser double-resonance experiments. In three kinds of experiments populations pumped to a specific rotational level were followed: out of the pumped level, to the levels above, and to the levels below. The rates of loss from the pumped level and transfer to the lower levels were strongly affected by lasing between rotational levels. Data for gain and laser intensity were incorporated into a kinetic rate model to evaluate transfer rates.