Atom probe analysis of the dissociation of CO and N2 gases on W(110)-oriented tips

In order to extend the application range of an atom probe (AP) to the study of the gas-surface catalytic phenomena, the proper interpretation of the electric field induced dissociation of molecular gases is greatly needed. We first show that the AP can discriminate between physically absorbed and trapped states based on the difference in desorption field strength. Then we show that the field-induced dissociation of CO and N-2 gases on a W(110)-oriented tip can be estimated. Finally, the activation energy required for conversion from the trapped state to the dissociated state is deduced from the temperature dependence of the dissociation probability. (C) 1999 Elsevier Science B.V. All rights reserved.