Infrared, far-infrared, and maser emission from the nascent water formed in the OH-H-2 reaction

It is known that most water in the interstellar medium is formed in the rea ction. It is also OH + H-2 known that the newly formed water molecules from this reaction are born in highly excited vibrational and rotational states . Even at densities of 10(9) cm(-3) in the interstellar medium these states relax in a fast IR radiation cascade to the ground state(s) of water emitt ing IR, far-infrared (FIR), and microwave light. Because this effect has no t been included in the astrophysical literature before, we analyze here the intensity of this spontaneous emission at 6 mum, in the FIR and the microw ave region. We calculate stationary rotational state distributions using a quantitative model that includes the nascent formation, the subsequent spon taneous emission, photolysis, and collisional redistribution. The radiation cascade yields FIR radiation and an alternative pump mechanism for water m asers. For regions of massive water formation it is shown that the stationa ry rotational population is much less affected by collisions than by the na scent water formation. It is speculated that nascent reactive water might b e responsible for the near-IR spectra at 6 mum, for the pure rotational tra nsitions in the FIR radiation, and for the maser H2O radiation.