Multiscale Visualization of Step-Edge-Mediated Oxidation Dynamics on Cu(111)

Abstract

The atomistic pathways linking oxygen adsorption, surface reconstruction, and oxide nucleation during metal oxidation remain incompletely understood. Here, we investigate the initial oxidation of Cu(111) using a correlative low-energy electron microscopy (LEEM) and scanning tunneling microscopy (STM) approach that bridges mesoscale surface evolution with atomic-scale structural characterization. In situ LEEM reveals that oxidation initiates preferentially at step edges and subsequently propagates across terraces through the growth and coalescence of oxygen-induced domains. Increasing temperature significantly accelerates oxidation kinetics, suppresses terrace nucleation, and promotes dynamic surface reconstruction. Complementary STM observations directly visualize the nucleation and lateral growth of Cu–O structures from step edges and reveal the formation of reconstructed oxide terraces, Cu–O islands, and locally ordered oxide domains. Fourier-transform analysis indicates that the oxidized surface is dominated by short-range ordered Cu–O precursor phases rather than long-range ordered oxide structures. Together, these results establish a temperature-dependent oxidation mechanism governed by step-edge-mediated oxygen incorporation, surface diffusion-driven domain growth, and dynamic surface reconstruction. The findings provide direct multiscale insight into the early stages of Cu(111) oxidation and the fundamental processes controlling oxide nucleation and growth on metal surfaces.