Suppression of D adsorption and D by H abstraction on graphite (0 0 0 1) surfaces by adsorbed water

Water was adsorbed prior to and after admission of D atoms to HOPG surfaces which essentially consisted of graphite (0 0 0 1) patches. After formation of a water monolayer at 100 K or a compact assembly of ice crystallites at 120 K adsorption of D on graphite was completely suppressed. Likewise, an adsorbed monolayer of water or ice crystals on D covered graphite (0 0 0 1) surfaces prevents abstraction of D by gaseous H atoms. Since icy mantles are expected to exist on interstellar grain particles, the results suggest that H by H abstraction reactions on graphitic particles proposed as origin of molecular hydrogen in the interstellar medium must be reconsidered.