Abstract
Gas molecules possess various internal degrees of freedom. Whereas recent advances in surface dynamics have clarified the roles of translational, vibrational and rotational motion in gas-surface reactions, the effect of its electron spin on surface reactions remains poorly understood. Here, we demonstrate the spin dependence of H adsorption and abstraction reactions on a Ni surface using a spin-polarized atomic-hydrogen beam. The results indicate that H adsorption is suppressed when the H electron spin is oriented perpendicular to the magnetization direction of the Ni(111) surface. Furthermore, the same spin preference is observed for the H abstraction reaction on a D-covered surface. These findings suggest that controlling the spin orientation of molecules and surfaces by applying an external magnetic field provides a viable means to modulate surface reaction rates.