2 research outputs found
Measuring the Three-Dimensional Structure of Ultrathin Insulating Films at the Atomic Scale
The increasing technological importance of thin insulating layers calls for a thorough understanding of their structure. Here we apply scanning probe methods to investigate the structure of ultrathin magnesium oxide (MgO) which is the insulating material of choice in spintronic applications. A combination of force and current measurements gives high spatial resolution maps of the local three-dimensional insulator structure. When force measurements are not available, a lower spatial resolution can be obtained from tunneling images at different voltages. These broadly applicable techniques reveal a previously unknown complexity in the structure of MgO on Ag(001), such as steps in the insulator–metal interface
Pasteur’s Experiment Performed at the Nanoscale: Manual Separation of Chiral Molecules, One by One
Understanding the principles of molecular
recognition is a difficult task and calls for investigation of appropriate
model systems. Using the manipulation capabilities of scanning tunneling
microscopy (STM) we analyzed the chiral recognition in self-assembled
dimers of helical hydrocarbons at the single molecule level. After
manual separation of the two molecules of a dimer with a molecule-terminated
STM tip on a Cu(111) surface, their handedness was subsequently determined
with a metal atom-terminated tip. We find that these molecules strongly
prefer to form heterochiral pairs. Our study shows that single molecule
manipulation is a valuable tool to understand intermolecular recognition
at surfaces