| AVS 56th International Symposium & Exhibition | |
| Surface Science | Wednesday Sessions |
| Session SS2-WeM |
| Session: | Surface Chemistry and Dynamics |
| Presenter: | I. Stass, Lawrence Berkeley National Laboratory |
| Authors: | I. Stass, Lawrence Berkeley National Laboratory S. Maier, Lawrence Berkeley National Laboratory M. Salmeron, Lawrence Berkeley National Laboratory |
| Correspondent: | Click to Email |
Ammonia (NH3) can be potentially used for hydrogen storage, because the dissociation of ammonia molecules generates hydrogen. Although Ruthenium is the best elementary metallic catalyst for ammonia synthesis, the exact reaction mechanisms at the atomic scale of both synthesis and dissociation over the Ruthenium surface have yet to be understood. Previously, the dehydrogenated products were obtained by annealing the sample and characterized by spectroscopic methods.
We studied the dehydrogenation of single ammonia molecules adsorbed on a Ru(0001) surface, by means of scanning tunneling microscopy (STM) at low temperature. The sudden change in tunneling current during the dissociation process allows us to study the dissociation mechanism and rate of single molecules in detail. We observe the different dehydrogenation steps after selectively applying voltage pulses in the order of a few volts between STM tip and an adsorbed ammonia molecule. The various dissociation products show a distinct imaging contrast. Together with the assignment of the adsorption site, this leads to the identification of the dissociation products. We will discuss to what extent electron induced and electric field driven processes, respectively, are affecting the dissociation mechanism of ammonia and its dissociation products.