Collisional excitation of water by hydrogen atoms

Abstract

We present quantum dynamical calculations that describe the rotational excitation of H2O due to collisions with H atoms. We used a recent, high-accuracy potential energy surface, and solved the collisional dynamics with the close-coupling formalism, for total energies up to 12 000 cm-1. From these calculations, we obtained collisional rate coefficients for the first 45 energy levels of both ortho- and para-H2O and for temperatures in the range T = 5-1500 K. These rate coefficients are subsequently compared to the values previously published for the H2O/He and H2O/H2 collisional systems. It is shown that no simple relation exists between the three systems and that specific calculations are thus mandatory.