Measuring the Charge State of an Adatom with Noncontact Atomic Force Microscopy

作者：Gross Leo^*; Mohn Fabian; Liljeroth Peter; Repp Jascha; Giessibl Franz J; Meyer Gerhard

来源：Science, 2009, 324(5933): 1428-1431.

DOI：10.1126/science.1172273

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.

• 出版日期2009-6-12