Enhanced atom mobility on the surface of a metastable film

Direct Measurements of Surface Strain-Mediated Lateral Interactions between Adsorbates in Colloidal Heteroepitaxy

Surface strain can alter the dynamics of adsorbates, and often, the adsorbates themselves induce and interact via their surface strain fields. In epitaxy, such strain-mediated effects get further compounded when a misfit strain exists due to lattice mismatch between the growing film and substrate. Here, we carry out particle-resolved imaging of heteroepitaxial growth of multilayer colloidal films where the particles interact via a short-range attraction. Surprisingly, although the misfit strain relaxed systematically with film thickness, the adcolloid diffusivity was nonmonotonic. We show that this nonmonotonicity stems from the competition between the spatial extent of self-induced in-layer strain and the short interaction range. Importantly, we provide direct evidence for long-ranged strain-mediated interactions between adsorbates and show that it alters the growing film's morphology.

Controlling the Electronic and Structural Coupling of C60 Nano Films on Fe(001) through Oxygen Adsorption at the Interface

C₆₀ molecules coupled to metals form hybrid systems exploited in a broad range of emerging fields, such as nanoelectronics, spintronics, and photovoltaic solar cells. The electronic coupling at the C₆₀/metal interface plays a crucial role in determining the charge and spin transport in C₆₀-based devices; therefore, a detailed understanding of the interface electronic structure is a prerequisite to engineering the device functionalities. Here, we compare the electronic and structural properties of C₆₀ monolayers interfaced with Fe(001) and oxygen-passivated Fe(001)-p(1 × 1)O substrates. By combining scanning tunneling microscopy and spectroscopy, Auger electron spectroscopy, photoemission and inverse photoemission spectroscopies, we are able to elucidate the striking effect of oxygen on the interaction between Fe(001) and C₆₀. Upon C₆₀ deposition on the oxygen-passivated surface, the oxygen layer remains buried at the C₆₀/Fe(001)-p(1 × 1)O interface, efficiently decoupling the fullerene film from the metallic substrate. Tunneling and photoemission spectroscopies reveal the presence of well-defined molecular resonances for the C₆₀/Fe(001)-p(1 × 1)O system, with a large HOMO-LUMO gap of about 3.4 eV. On the other hand, for the C₆₀/Fe(001) interface, a strong hybridization between the substrate states and the C₆₀ orbitals occurs, resulting in broader molecular resonances.