Vibrational analysis of the NH + N coadsorbate on Ru(0001)

Using high-resolution electron energy loss spectroscopy (HREELS) and thermal desorption spectroscopy (TDS) we studied the thermal decomposition of NH3 on the Ru(0001) surface. Exposing Ru(0001) to high doses of NH3 at sample temperatures above the desorption temperature of NH3 a thermally stabilized N + NH coadsorbate phase is formed in which a relatively large coverage of N + NH (θN + NH=0.47) can be achieved. In this phase NH is stable up to 460 K. The thermal destabilization is accompanied by a first-order desorption of hydrogen and nitrogen. The thermal stabilization is discussed taking into account the different work function changes upon NH and N adsorption. Within the N+NH phase the Ru-NH stretch mode intensity is very weak. Similarities with the Cs+CO system are discussed