Hard repulsive barrier in hot adatom motion during dissociative adsorption of oxygen on Ag(100)

Abstract

Random pairing simulation and low temperature scanning tunneling microscopy (STM) are used to investigate the detailed O(2) dissociative adsorption processes at 200 K for various coverages. The distribution of oxygen adatoms shows a strong repulsion between the adsorbates with a radius of similar to 0.8 nm. The comparison between STM results and simulation reveals two prominent pairing distances of 2 and 4 nm and their branching ratio is about 2:1. These findings shed new light on the origin of the large intrapair distances found and on the process behind the empirical "eight-site rule.".