Jülich Researchers Develop Ultrahigh-Resolution 3D
Microscopy Technique for Electric Fields
(July 8, 2015) Using
a single molecule as a sensor, scientists in Jülich have successfully imaged
electric potential fields with unrivalled precision. The ultrahigh-resolution
images provide information on the distribution of charges in the electron
shells of single molecules and even atoms. The 3D technique is also contact-free.
The first results achieved using "scanning quantum dot microscopy"
have been published in the current issue of Physical Review Letters. The
related publication was chosen as the Editor's suggestion and selected as a
Viewpoint in the science portal Physics. The technique is relevant for diverse
scientific fields including investigations into biomolecules and semiconductor
materials.
"Our method is the first to image electric fields near
the surface of a sample quantitatively with atomic precision on the
sub-nanometre scale," says Dr. Ruslan Temirov from Forschungszentrum
Jülich. Such electric fields surround all nanostructures like an aura. Their
properties provide information, for instance, on the distribution of charges in
atoms or molecules.
For their measurements, the Jülich researchers used an
atomic force microscope. This functions a bit like a record player: a tip moves
across the sample and pieces together a complete image of the surface. To image
electric fields up until now, scientists have used the entire front part of the
scanning tip as a Kelvin probe. But the large size difference between the tip
and the sample causes resolution difficulties – if we were to imagine that a
single atom was the same size as a head of a pin, then the tip of the
microscope would be as large as the Empire State Building.