Molecular-sized ball bearings

It turns out that functionality we know in everyday life also exists at a molecular-sized nano-level. Measurements by mass spectrometers had shown some time ago that precisely thirteen boron atoms can enter into a particularly stable form called a magic cluster. It has a flat structure and consists of two concentric rings: an inner ring consisting of three boron atoms and an outer ring consisting of ten boron atoms.

Some years ago, theoretical chemist Thomas Heine, now at the University of Leipzig, predicted that these two rings would permit almost frictionless distortion against each other without affecting the overall stability of the molecule in any ways. This results in a molecular-sized ball bearing that permits a virtually frictionless counter-rotating movement of the atomic rings.

Proving this prediction was not free of challenges and could be done only through spectroscopic measurements with a free electron laser at Fritz-Haber-Institute in Berlin. Commercially available lasers are unsuitable for this proof because it requires extremely intense laser radiation in a narrowly defined wavelength range. By measuring the infrared spectrum and accompanying calculations of quantum mechanics it was possible to prove the functionality of the molecular ball bearing.

This is one of the first practical indications that quantum effects may be put to targeted use as part of the functionality of molecular systems. Despite the fact that applications are still in the distant future, their promise and potential is immense. This comes as no surprise that the 2016 Nobel Prize in Chemistry was awarded for discoveries in the area of molecular machines.