| AVS 54th International Symposium | |
| Surface Science | Tuesday Sessions |
| Session SS-TuP |
| Session: | Surface Science Poster Session |
| Presenter: | H. Bluhm, Lawrence Berkeley National Laboratory |
| Authors: | D.E. Starr, Lawrence Berkeley National Laboratory Ch.D. Weiss, Lawrence Berkeley National Laboratory S. Yamamoto, Stanford Synchrotron Radiation Laboratory A. Nilsson, Stanford Synchrotron Radiation Laboratory M. Salmeron, Lawrence Berkeley National Laboratory H. Bluhm, Lawrence Berkeley National Laboratory |
| Correspondent: | Click to Email |
The adsorption of NOx compounds onto alkaline-earth metal-oxide surfaces has recently received a great deal of attention due to the use of alkaline-earth metal-oxides as NOx storage compounds for controlling emissions during combustion under fuel lean conditions. In this work we have studied the adsorption of NO2 onto MgO(100) thin films grown on Ag(100) ranging from 2 ML to over 8 ML in thickness and NO2 exposures from a few hundred Langmuir up to twenty thousand Langmuir at 300 K. We have used the Ambient Pressure Photoemission Spectroscopy experiment at beamline 11.0.2 of the Advanced Light Source to characterize this system using both core level and valence band photoemission as well as Auger-yield Near Edge X-ray Adsorption Spectroscopy. On thin films (~ 2 ML thick) we observe exclusively the adsorption of NO2 with coverages of ~ 0.5 ML for all exposures. As the film thickness increases the initial amount of NO2 adsorbed onto the surface decreases (~0.05 ML on films with thicknesses greater than ~5 ML) and we observe the formation of NO3 with increasing exposures. The final amount of NO3 on the surface of films thicker than 5 ML is ~ 0.3 ML. This indicates that the adsorption and reaction of NO2 on the surfaces of MgO(100) can, to some extent, be controlled by growing MgO(100) films of specific thicknesses. The mechanism of NO2 stabilization on the surfaces of thin MgO(100) films on Ag(100) will also be presented.