2009/06/11 by Leo Gross, Fabian Mohn, Peter Liljeroth +3 · 3 citations
Physics and Astronomy · Engineering · #Force Microscopy Techniques and Applications #Molecular Junctions and Nanostructures #Surface and Thin Film Phenomena
paper · doi:10.1126/science.1172273
openalex publication_date 2009/06/11 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
Charge states of atoms can be investigated with scanning tunneling microscopy, but this method requires a conducting substrate. We investigated the charge-switching of individual adsorbed gold and silver atoms (adatoms) on ultrathin NaCl films on Cu(111) using a qPlus tuning fork atomic force microscope (AFM) operated at 5 kelvin with oscillation amplitudes in the subangstrom regime. Charging of a gold atom by one electron charge increases the force on the AFM tip by a few piconewtons. Moreover, the local contact potential difference is shifted depending on the sign of the charge and allows the discrimination of positively charged, neutral, and negatively charged atoms. The combination of single-electron charge sensitivity and atomic lateral resolution should foster investigations of molecular electronics, photonics, catalysis, and solar photoconversion.