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 SS2-WeM

Paper SS2-WeM5
Hydrogenation of Oxygen on Pd(111)

Wednesday, October 31, 2001, 9:40 am, Room 121

Session: Surface Reactions on Metals
Presenter: T. Mitsui, Lawrence Berkeley National Laboratory
Authors: T. Mitsui, Lawrence Berkeley National Laboratory
M.K. Rose, University of California, Berkeley
E. Fomine, University of California, Berkeley
F. Ogletree, Lawrence Berkeley National Laboratory
M. Salmeron, Lawrence Berkeley National Laboratory
Correspondent: Click to Email
The reaction of hydrogen with (2x2) oxygen islands on Pd(111) has been studied with scanning tunneling microscopy under UHV conditions. Hydrogenation of oxygen, to form OH, was observed at 25 K. The reaction destabilizes the (2x2) ordering of oxygen and results in the formation of new (@sr@3x@sr@3) islands above 120 K. The OH islands remain stable up to 210 K even after the H@sub 2@ gas phase has been removed. Above this temperature, however the OH species decompose back to oxygen which reorganizes into (2x2) structures. The (@sr@3x@sr@3) OH islands can be formed again by additional hydrogen. If H@sub 2@ gas phase (10@super -8@ torr) is maintained during heating at 220 K, the (2x2) oxygen islands disappear completely from the surface by forming of H@sub 2@O that desorbs. Based on these results, the mechanisms of the formation of H@sub 2@O on Pd(111) from oxygen and hydrogen will be discussed.