DEUTERATION OF PROPYLENE OVER PALLADIUM OVERLAYERS ON TANTALUM

The deuteration of propylene over Pd-covered Ta surfaces was studied by mass spectroscopy. The largest reaction rate for the formation of C3D8 and C3D7H occurred at coverages slightly greater than 0.5 monolayers and also at somewhat greater than 1 monolayer. The increase in formation Of C3D8 and C3D7H at fractional coverages was expected. However, in this work we find in addition a minimum in the reaction at one monolayer. We argue that this result demonstrates conclusively the dramatic effect of electronic structure on surface reactivity for the Pd-covered Ta surface.