IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Surface Science Wednesday Sessions
       Session SS+SC-WeM

Paper SS+SC-WeM7
Adsorption of NO and NO@sub 2@ on Barium Oxide: Surface Nitrition and Nitration

Wednesday, October 31, 2001, 10:20 am, Room 122

Session: Adsorption on Semiconductor and Metal Oxide Surfaces
Presenter: M. Miletic, University of Michigan
Authors: P.J. Schmitz, Ford Motor Company
R.J. Baird, Ford Motor Company
M. Miletic, University of Michigan
J.L. Gland, University of Michigan
Correspondent: Click to Email
Alkaline earth oxides surfaces are known to trap NOx species by chemisorption even under excess oxygen conditions typical of lean burn engines exhaust. These oxides, particularly barium oxide, have been proposed as active components in cyclic automotive NOx abatement strategies because of their ability to store and release NOx under rich/lean exhaust cycling. However, molecular understanding of the adsorption and reactions of NO, and NO2 on alkaline earth oxide surfaces remains incomplete. A series of XPS and temperature programmed studies of NO and NO2 adsorption and reaction on model barium oxide thin films prepared in-situ are reported here. These experiments indicate that charge transfer and reactive chemisorption play an important role even during low temperature adsorption on barium oxide surfaces. Nitrite and nitrate species form preferentially on reactive adsorption sites and can be reactively desorbed in the 400 to 600 K temperature range. The coverage of the precursor molecular species plays an unexpected role both in reactive adsorption and desorption on barium oxide surfaces. These results are discussed in terms of recent DFT calculations which highlight the importance of reactive configurations, charge transfer, and surface oxidation/reduction processes.