Lyman-alpha and Balmer-series fluorescence from hydrogen photofragments of H2O vapor

Production cross sections associated with the atomic hydrogen Lyman-alpha and Balmer-series (3-9 to 2) fluorescence observed in H2O photodissociation are measured, and maximum fluorescence production cross sections for the two series are reported. Repulsive potential energy curves corresponding to the respective pseudodiatomic OH-H(n) molecule are constructed according to the Franck-Condon principle, and the efficiencies for converting H(2S) to H(2P) by H2 collisions and by H2O collisions are estimated. The data are considered with reference to cometary photochemistry.