Dynamics of hydrogen dissociation on stepped platinum.

We have studied the reactivity of hydrogen on the Pt(211) stepped surface using supersonic molecular beam techniques. We observe an energy dependence that is indicative of indirect adsorption below 9 kJ mol(-1) and direct adsorption between 0 and 37 kJ mol(-1). Comparison of our results to predictions based on six-dimensional quantum dynamics calculations for Pt(211) [R. A. Olsen et al., J. Chem. Phys. 128, 194715 (2008)] yields reasonable agreement. Discrepancies between theory and our experiments at low kinetic energy strongly indicate that the wells in the used potential energy surface are too shallow. Discrepancies at high kinetic energy point toward neglect of degrees of freedom vital to capture the full dynamics.