title: Direct Observation of Individual Charges and Their Dynamics on Graphene by Low-Energy Electron Holography.
abstract: Visualizing individual charges confined to molecules and observing their dynamics with high spatial resolution is a challenge for advancing various fields in science, ranging from mesoscopic physics to electron transfer events in biological molecules. We show here that the high sensitivity of low-energy electrons to local electric fields can be employed to directly visualize individual charged adsorbates and to study their behavior in a quantitative way. This makes electron holography a unique probing tool for directly visualizing charge distributions with a sensitivity of a fraction of an elementary charge. Moreover, spatial resolution in the nanometer range and fast data acquisition inherent to lens-less low-energy electron holography allows for direct visual inspection of charge transfer processes.
authors.affiliation: Physics Department, University of Zurich , Winterthurerstrasse 190, 8057 Zurich, Switzerland.
authors.forename: Tatiana
authors.initials: T
authors.lastname: Latychevskaia
authors.affiliation: Physics Department, University of Zurich , Winterthurerstrasse 190, 8057 Zurich, Switzerland.
authors.forename: Flavio
authors.initials: F
authors.lastname: Wicki
authors.affiliation: Physics Department, University of Zurich , Winterthurerstrasse 190, 8057 Zurich, Switzerland.
authors.forename: Jean-Nicolas
authors.initials: JN
authors.lastname: Longchamp
authors.affiliation: Physics Department, University of Zurich , Winterthurerstrasse 190, 8057 Zurich, Switzerland.
authors.forename: Conrad
authors.initials: C
authors.lastname: Escher
authors.affiliation: Physics Department, University of Zurich , Winterthurerstrasse 190, 8057 Zurich, Switzerland.
authors.forename: Hans-Werner
authors.initials: HW
authors.lastname: Fink
keywords: Low-energy electrons; adatoms; charge transfer; graphene; holography