SoylentNews

RandomFactor writes:

Researchers from Jülich, Germany and the University of Magdeburg have developed a method of measuring the electric potentials of individual atoms using quantum dots.

Until now, it has been nearly impossible to record electric potentials of individual molecules or atoms. All available methods have difficulty distinguishing from other forces at that scale.

The new scanning quantum dot microscopy method, which was recently presented in the journal Nature Materials by scientists from Forschungszentrum Jülich together with partners from two other institutions, could open up new opportunities for chip manufacture or the characterization of biomolecules such as DNA.

Scanning quantum dot microscopy involves attaching a single organic molecule—the quantum dot—to the tip of an atomic force microscope. This molecule then serves as a probe. "The molecule is so small that we can attach individual electrons from the tip of the atomic force microscope to the molecule in a controlled manner," explains Dr. Christian Wagner, head of the Controlled Mechanical Manipulation of Molecules group at Jülich's Peter Grünberg Institute (PGI-3).

The microscope tip acts as a shield dampening effects from fields from the sample that are further away, allowing for the precise quantization of the electric fields of individual atoms.

"An atomic force microscope works a bit like a record player," says Wagner. "The tip moves across the sample and pieces together a complete image of the surface. In previous scanning quantum dot microscopy work, however, we had to move to an individual site on the sample, measure a spectrum, move to the next site, measure another spectrum, and so on, in order to combine these measurements into a single image. With the Magdeburg engineers' controller, we can now simply scan the whole surface, just like using a normal atomic force microscope. While it used to take us 5-6 hours for a single molecule, we can now image sample areas with hundreds of molecules in just one hour."

This approach works at an increased distance from the target (2-3nm) making it superior on 'rough' surfaces such as DNA molecules.

Journal Reference
Christian Wagner et al, Quantitative imaging of electric surface potentials with single-atom sensitivity, Nature Materials (2019). DOI: 10.1038/s41563-019-0382-8

Original Submission