How acidic are atoms?

1/2 images 1 of 2 images or videos - The acidity of molecules can be easily determined, but until now it was not possible to measure this important property for atoms on a surface. With a new microscopy technique from the Vienna University of Technology (TU Wien), this has now been achieved. The degree of acidity or alkalinity of a substance is crucial for its chemical behavior. The decisive factor is the so-called proton affinity, which indicates how easily an entity accepts or releases a single proton. While it is easy to measure this for molecules, it has not been possible for surfaces. This is important because atoms on surfaces have very different proton affinities, depending on where they sit. Researchers at TU Wien have now succeeded in making this important physical quantity experimentally accessible for the first time: Using a specially modified atomic force microscope, it is possible to study the proton affinity of individual atoms.