In the quantum world, molecules are always on the move. And for the first time ever, scientists have directly captured these tiny quantum dances in action—and they did so by blowing them up real good.
Even at absolute zero, individual particles constantly vibrate without a fixed position, a phenomenon referred to as zero-point motion. In a paper published August 7 in Science, researchers at European XFEL harnessed this behavior for the 2-iodopyridine molecule, which consists of 11 atoms. By blasting the molecule with powerful, short bursts of X-ray pulses, the team created a “microscopic big bang” that allowed them to track, reconstruct, and therefore visualize the molecule’s quantum fluctuations.
“We were able to see that the atoms don’t just vibrate individually, but that they vibrate in a coupled manner, following fixed patterns,” study senior author Till Jahnke said in a statement. Jahnke, a physicist at the Institute for Nuclear Physics at Goethe University Frankfurt in Germany, added that iodopyridine “features a whole repertoire of 27 different vibrational modes,” a fascinating quantum behavior that cannot be explained classically.
The team used a technique called Coulomb Explosion Imaging, which zaps molecules with X-rays to knock out swathes of electrons from the target molecule. This makes the molecule positively charged overall, causing the atom parts to repel each other and eventually fly apart. A special instrument quickly recorded the shape and motion of each fragment from the explosion, which lasted less than a femtosecond (a quadrillionth of a second).
Based on the records, the researchers modeled the explosion to “visualize” the motion of the molecule, confirming that it aligned with the correlated zero-point motion they were hoping to observe.
Other than bringing us a tangible representation of the quantum world, the new results represent the “fingerprints” of the atoms’ quantum behavior. Using this technique to study similar phenomena for other molecules could open entirely new avenues for physicists to investigate individual molecules with unprecedented precision, the researchers state.
“In the future, this technique could be used to study even larger molecules, and time-resolved movies of their internal motions are now possible,” said Michael Meyer, study co-author and a scientist at the Hamburg Centre for Ultrafast Imaging in Germany, in an XFEL statement.
“Our goal is to go beyond the dance of atoms and observe in addition the dance of electrons—a choreography that is significantly faster and also influenced by atomic motion,” said Jahnke. “With our apparatus, we can gradually create real short films of molecular processes—something that was once unimaginable.”
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