Vibrational effects on the dissociative adsorption of H2 on metal surfaces

• Main Authors: Arboleda, Nelson B., Jr., Kasai, Hideaki, Diño, Wilson Agerico, Nakanishi, Hiroshi
• Format: text
• Published: Animo Repository 2008
• Subjects: Atomic hydrogen; Metals—Surfaces; Physics
• Online Access: https://animorepository.dlsu.edu.ph/faculty_research/11932
• Institution: De La Salle University

We investigate and discuss the interaction of molecular/atomic hydrogen with various metal surfaces. Using previously obtained potential energy surfaces (PESs) for the dissociative adsorption of H2 on the (0001) surfaces of Mg, Ti, and La, we determine the sticking probability plots for H2 as functions of its initial translational energy and vibrational state. The plots obtained indicate that H2 is best adsorbed on La, followed by Ti, and then Mg, and that increasing its initial vibrational state has the strongest effect of enhancing its adsorption on Mg, followed by Ti and then La. These are attributed to the high activation barrier close to the curved region along the reaction path (path of least potential) in the potential energy surface (PES) corresponding to the dissociative adsorption of H2 on Mg. The corresponding barrier for Ti is small and far from the curved region, while it is absent for La (non-activated reaction). We also investigate the effects of H-induced lattice relaxation on the H absorption into (desorption from) a Li(100) surface using a previously obtained potential energy curve (PEC) for the absorption of H on Li via the bridge site. Our results show that the H motion and the surface lattice relaxation are dynamically coupled and, depending on the initial condition, the surface lattice motion either promotes or hinders the penetration of H into (desorption from) the surface (subsurface). At low translational energy, the Li lattice has sufficient time to relax effectively reducing the energy barrier for H absorption and desorption.