While high-quality defect-free epitaxial graphene can be efficiently grown on metal substrates, strong interaction with the supporting metal quenches its outstanding properties. Thus, protocols to transfer graphene to insulating substrates are obligatory, and these often severely impair graphene properties by the introduction of structural or chemical defects. Here we describe a simple and easily scalable general methodology to structurally and electronically decouple epitaxial graphene from Pt(111) and Ir(111) metal surfaces. A multi-technique characterization combined with calculations was employed to fully explain the different steps involved in the process. It was shown that, after a controlled electrochemical oxidation process, a single-atom thick metal-hydroxide layer intercalates below graphene, decoupling it from the metal substrate. This decoupling process occurs without disrupting the morphology and electronic properties of graphene. The results suggest that suitably optimized electrochemical treatments may provide effective alternatives to current transfer protocols for graphene and other 2D materials on diverse metal surfaces.

Chemical information can be obtained by using atomic force microscopy (AFM) and force spectroscopy (FS) with atomic or molecular resolution, even in liquid media. The aim of this paper is to demonstrate that single molecules of avidin and streptavidin anchored to a biotinylated bilayer can be differentiated by using AFM, even though AFM topographical images of the two proteins are remarkably alike. At physiological pH, the basic glycoprotein avidin is positively charged, whereas streptavidin is a neutral protein. This charge difference can be determined with AFM, which can probe electrostatic double-layer forces by using FS. The force curves, owing to the electrostatic interaction, show major differences when measured on top of each protein as well as on the lipid substrate. FS data show that the two proteins are negatively charged. Nevertheless, avidin and streptavidin can be clearly distinguished, thus demonstrating the sensitivity of AFM to detect small changes in the charge state of macromolecules.

We study mechanically exfoliated nanosheets of franckeite by quantitative optical microscopy. The analysis of transmission-mode and epi-illumination-mode optical microscopy images provides a rapid method to estimate the thickness of the exfoliated flakes at first glance. A quantitative analysis of the optical contrast spectra by means of micro-reflectance allows one to determine the refractive index of franckeite over a broad range of the visible spectrum through a fit of the acquired spectra to a model based on the Fresnel law.

There is a correlation between the corrosion resistance, structure, roughness and the porosity of TaN sputtered films.