Due to the Heisenberg uncertainty principle of quantum physics, atoms and molecules never come completely to rest, even in their lowest energy state. Researchers at European XFEL in Schenefeld near Hamburg have now been able to directly measure this quantum motion in a complex molecule for the first time. For this, however, as they report in the journal Science, they had to make the molecule explode in the process.
Absolute standstill only exists in classical physics. In the quantum world, even the ground state with the lowest energy is characterised by persistent fluctuations. This is due to a quantum-mechanical principle discovered by Werner Heisenberg a hundred years ago during the development of quantum mechanics. The so-called zero-point fluctuations are a quantum effect that prevents atoms from remaining precisely at a fixed position, even at temperatures near absolute zero. At European XFEL in Schenefeld, researchers have now made the previously invisible directly observable – and the quantum world a bit more tangible.
An international team led by Rebecca Boll from the SQS (Small Quantum Systems) instrument at European XFEL in Schenefeld, Ludger Inhester from the DESY research centre, and Till Jahnke from the Max Planck Institute for Nuclear Physics in Heidelberg, succeeded in visualising the collective trembling of an entire molecule. Using a sophisticated experiment and refined data analysis, they were able to measure the quantum fluctuations of the 2-iodopyridine molecule (C5H4IN), which consists of eleven atoms – a milestone in molecular imaging. They describe their work in the renowned journal Science.
The researchers employed a method as spectacular as its name: Coulomb Explosion Imaging. The ultrashort, extremely intense X-ray laser pulses of European XFEL strip numerous electrons from the atoms of individual 2-iodopyridine molecules very rapidly. The remaining atomic cores become positively charged, repelling each other. The result resembles a microscopic big bang: the atomic cores fly apart in an explosion.
Read more on European XFEL website
Image: Visualisation of collective quantum fluctuations of a complex 2-iodopyridine molecule
Credit: European XFEL / Tobias Wüstefeld)