Physicists from the Max Planck Society have achieved a groundbreaking milestone by capturing the real-time break-up of C60 fullerenes under intense laser fields. This innovative study utilized ultrashort X-ray pulses from accelerator-based free electron lasers (FELs) to observe molecular dynamics as they occur, providing new insights into the behavior of these complex molecules.
The experiment took place at the Linac Coherent Light Source (LCLS) of the SLAC National Accelerator Laboratory in the United States, marking the first instance where researchers could directly visualize the strong laser-driven dynamics of the iconic football-shaped molecule, C60. The results are detailed in the journal Science Advances.
The research involved collaboration between physicists from two Max Planck Institutes: the Institute for Nuclear Physics in Heidelberg and the Institute for the Physics of Complex Systems in Dresden, alongside partners from the Max Born Institute in Berlin and institutions in Switzerland, the United States, and Japan.
Through the analysis of the X-ray diffraction patterns produced during the interaction of C60 with a strong infrared (IR) laser pulse, researchers were able to extract two key parameters: the average radius R of the molecule and the Guinier amplitude A. The radius relates to the molecule’s expansion or deformation, while the Guinier amplitude provides insights into the strength of the X-ray scattering signal, which correlates to the number of atoms in the molecule.
The study conducted experiments at varying laser intensities, ranging from 1×1014 W/cm2 to 8×1014 W/cm2. At low intensities, the C60 molecule began to expand before fragmentation occurred, as indicated by a slight decrease in the Guinier amplitude. As the intensity increased, a more pronounced fragmentation was observed, with rapid expansion and a significant decrease in amplitude occurring almost immediately at the peak of the laser pulse.
Model calculations conducted at the Max Planck Institute for the Physics of Complex Systems suggested that while there was some qualitative agreement with experimental results, discrepancies remained. The model predicted an oscillatory behavior in the radius and amplitude due to a periodic “breathing” of the molecule, which was not observed in the experimental data. To address this, researchers introduced an ultrafast heating mechanism impacting atomic positions, improving the alignment between the model and experimental findings.
The multi-electron dynamics driven by intense laser fields present a challenge for theoretical descriptions, as a complete quantum mechanical analysis is currently unattainable. The real-time observations of structural dynamics in C60 provide a vital platform for understanding fundamental quantum processes in increasingly complex molecular systems. This research holds significant potential for future advancements in controlling chemical reactions through laser interactions with matter.
For further details, refer to the study by Kirsten Schnorr et al., titled “Visualizing the strong-field induced molecular break-up of C60 via X-ray diffraction,” published in Science Advances on November 21, 2025.
