Orientation of nitrous oxide on palladium(1 1 0) by STM

The adsorption structure of N2O on Pd(1 1 0) was analyzed below 14 K by scanning-tunneling microscopy. The N2O monomer was oriented along the [0 0 1] direction in the on-top form. Furthermore, the formation of small aggregates extending along the [ 1 1 ¯ 0 ] direction was observed. The observed images were well-simulated for two types of cluster structures optimized by density-functional theory calculations. The components in the aggregates are proposed to be in a tilted form either on bridge sites or on-top sites.