Energy Transfer Dynamics of Formate Decomposition on Cu(110)

Energy transfer dynamics of formate (HCOO_a ) decomposition on a Cu(110) surface has been studied by measuring the angle-resolved intensity and translational energy distributions of CO₂ emitted from the surface in a steady-state reaction of HCOOH and O₂ . The angular distribution of CO₂ shows a sharp collimation with the direction perpendicular to the surface, as represented by cosⁿ θ (n=6). The mean translational energy of CO₂ is measured to be as low as 100 meV and is independent of the surface temperature (T_s ). These results clearly indicate that the decomposition of formate is a thermal non-equilibrium process in which a large amount of energy released by the decomposition reaction of formate is transformed into the internal energies of CO₂ molecules. The thermal non-equilibrium features observed in the dynamics of formate decomposition support the proposed Eley-Rideal (ER)-type mechanism for formate synthesis on copper catalysts.