Scanning-Tunneling Microscopy, Near-Edge X-ray-Absorption Fine Structure, and Density-Functional Theory Studies of N₂O Orientation on Pd(110)

Abstract

The orientation of adsorbed N2O on Pd(110) was studied by scanning tunneling microscopy, near-edge X-ray absorption fine structure (NEXAFS), and density functional theory. Below 14 K, N2O(a) forms clusters extending along the [1 10] direction as well as monomers oriented along the [001] direction. In the clusters, N2O is tilted with the terminal nitrogen bonding to the surface. The clusters are mobile at 14 K and stable at 8 K, whereas the monomers are stable at 14 K. In NEXAFS work at 60 K, remarkable anisotropy was found in the polarization dependence of π resonance, which was consistent with a mixture of the tilted and [001]-oriented forms.