Hideyuki Horino

Two-directional N2 desorption in thermal dissociation of N2O on Rh(110), Ir(110), and Pd(110) at low temperatures

Two-directional N2 desorption was found in N2O dissociation on Rh(110), Ir(110), and Pd(110) below 160 K by angle-resolved thermal desorption. N2O(a) is mostly dissociated during heating procedures, emitting N2(g) and leaving O(a). N2 showed four desorption peaks in the temperature range of 110–200 K. One of them commonly showed a cosine distribution, whereas the others sharply collimated off the surface normal in the plane along the [001] direction. The collimation angle was about 70° on Rh(110), 65° on Ir(110), and 43°–50° on Pd(110). A high-energy-atom assisted desorption model was proposed for N2 inclined emission.

Scanning-tunneling microscopy, near-edge X-ray-absorption fine structure, and density-functional theory studies of N2O orientation on Pd(110)

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.

Ad-molecule orientation and thermo- and photo-induced surface-aligned desorption

Two-directional N2 desorption was found in N2O decomposition on Pd(110) at 100–160 K. It collimated ±43° off the surface normal in the (001) plane. A hot-atom-assisted model is proposed for N2 desorption. Inclined O2 desorption was simulated by hot atoms emitted from aligned oxygen molecules on stepped Pt(112) at 308 nm irradiation.