RESUMO
AlCrFeCoNiCu0.5 thin films were fabricated by cathodic arc deposition under different substrate biases. Detailed characterization of the chemistry and structure of the film, from the substrate interface to the film surface, was achieved by combining high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, and atomic force microscopy. Computer simulations using the transport of ions in matter model were applied to understand the ion surface interactions that revealed the key mechanism of the film growth. The final compositions of the films are significantly different from that of the target used. A trend of elemental segregation, which was more pronounced with higher ion kinetic energy, was observed. The XPS results reveal the formation of [Formula: see text] and [Formula: see text] on the thin film surface. The grain size is shown to increase with the increasing of the ion kinetic energy. The growth of equiaxed grains contributed to the formation of a flat surface with a relatively low surface roughness as shown by atomic force microscopy.
RESUMO
A biomembrane force probe (BFP) has recently emerged as a native-cell-surface or in situ dynamic force spectroscopy (DFS) nanotool that can measure single-molecular binding kinetics, assess mechanical properties of ligand-receptor interactions, visualize protein dynamic conformational changes and more excitingly elucidate receptor mediated cell mechanosensing mechanisms. More recently, BFP has been used to measure the spring constant of molecular bonds. This protocol describes the step-by-step procedure to perform molecular spring constant DFS analysis. Specifically, two BFP operation modes are discussed, namely the Bead-Cell and Bead-Bead modes. This protocol focuses on deriving spring constants of the molecular bond and cell from DFS raw data.