Physical adsorption at the nanoscale: Towards controllable scaling of the substrate-adsorbate van der Waals interaction

The Lifshitz-Zaremba-Kohn (LZK) theory is commonly considered as the correct lar ge-distance limit for the van der Waals (vdW) interaction of adsorbates (atoms, molecules, or nanoparticle s) with solid substrates. In the standard approximate form, implicitly based on {\it local} dielectric fun ctions, the LZK approach predicts universal power laws for vdW interactions depending only on the dimensi onality of the interacting objects. However, recent experimental findings are challenging t he universality of this theoretical approach at finite distances of relevance for nanoscale assembly. Here, we present a combined analytical and numerical many-body study demonstrati ng that physical adsorption can be significantly enhanced at the nanoscale. Regardless of the band gap or th e nature of the adsorbate specie, we find deviations from conventional LZK power laws that extend to separation di stances of up to 10--20 nanometers. Comparison with recent experimental observation of ultra long-ranged vdW interac tions in the delamination of graphene from a silicon substrate reveals qualitative agreement with the present theory. The sensitivity of vdW interactions to the substrate response and to the adsorba te characteristic excitation frequency also suggests that adsorption strength can be effectively tuned in exp eriments, paving the way to an improved control of physical adsorption at the nanoscale.