Does N2 adsorption increase on strained fe monolayers?

Abstract

In general, the open metal faces of a crystal are more reactive that the close packed faces. In the case of transition metals, this has been sometimes rationalized within the so-called dband model. This model states that the closeness of the center of the d-band to the Fermi level causes an increase of chemisorption energies and a reduction of dissociation barriers for activated systems. These ideas stimulated an increasing interest in exploring the possibilities of surface strain as a promising tool to control the reactivity of different chemical species. In this context, K. Homann and co-workers reported that the inertness of Fe(110) towards N2 adsorption disappears on thin Fe layers grown on W(110). Motivated by this experimental data, we have studied the adsorption dynamics of N2 on a pseudomorphically grown monolayer of Fe on W(110). Classical molecular dynamics calculations within the frozen and oscillating (Generalized Langevin Oscillator model) surface approximations are performed on top of a six-dimensional potential energy surface calculated with density functional theory. The characteristics of the adiabatic PES, as well as the results of the dynamics will be compared with those obtained in our recent studies of N2 adsorption and dissociation on the clean Fe(110). We will show that molecular adsorption is clearly improved on the pseudomorphic Fe monolayer as a consequence of the modifications introduced on the adsorption wells.