OBSERVATION OF NEUTRAL ATOMIC FRAGMENTS FOR SPECIFIC 1S CORE EXCITATIONS OF AN ADSORBED MOLECULE

We have succeeded in detecting a neutral atomic fragment produced by e nergy-and polarization-specific molecular core electron excitations, e nabling a comparison of oxygen atom and oxygen ion yields from photon induced dissociation of chemisorbed CO molecules on the Ru(001) surfac e. Resonances in the O-0 atom yield are observed at 534 and 550 eV, bu t no enhancement is observed for higher-energy excitations which stepw ise increase the O+ yield. The mechanistic reasons for the similaritie s and differences in neutral and ionic fragment production are discuss ed, with emphasis on the influences of charge transfer and redistribut ion processes.