Use of In Situ X-ray Absorption to Probe Reactivity: A Catalysis Golden Rule

. In situ Raman spectroscopy shows the involvement of a common peroxide surface species. Kinetic data indicate a nonuniform surface and a rate-determining step (rds) involving electron transfer from the peroxide intermediate. The activation energy for all the catalysts is the same, indicating that the pre-exponential factor controls the rate. This can be associated with the electronic partition function (unoccupied density of states (DOS)), and X-ray absorption near-edge spectroscopy duly shows that the areas of the pre-edge peaks due to 1s to 3d transitions track the reactivity trends. The relation to the unoccupied DOS is analogous to Fermi's Golden Rule for electronic transitions, and we denote the finding here, applicable to reactions involving electron transfer, as a Catalysis Golden Rule.