Dynamics and Cycle of Interstellar H₂O and OH Masers

We prepsent an improved radiative pumping model for interstellar H₂O and OH masers. This overcomes the defects of former radiative models, and is compatible with astronomical conditions. For the regions of strong H₂O and OH formation, it is shown that the rotational population is affected by collisions less than that by radiation. A reasonable scheme for both regeneration and destruction of interstellar H₂O and OH molecules is investigated. It can close the dynamical cycle of interstellar H₂O and OH species, and can give an appropriate interpretation for both interstellar H₂O and OH masers. This model has been confirmed by experiments.