The direct spectroscopic observation of K* Rydberg states with principal quantum number n = 5 and 6 by anti-Stokes stimulated Raman spectroscopy at a K-promoted iron oxide surface (commercial catalyst for styrene production) proves that such states are formed thermally at surfaces of alkali-promoted heterogeneous catalysts. The K* states can be detected at 1 bar air pressure downward and at normal catalyst operating temperature in a vacuum. They exist in the boundary layer at the surface. Previous reports of the detection of K* Rydberg states from such catalysts using field ionization and laser ionization in a vacuum are thus confirmed. The implications for the reactivity of alkali-promoted catalysts are discussed.