Physicists have made significant strides in understanding molecular dynamics by using advanced X-ray imaging to capture the real-time break-up of the C60 fullerene molecule, commonly known as Buckminsterfullerene. This breakthrough was achieved through collaboration between experts from the Max Planck Institute for Nuclear Physics in Heidelberg, the Max Planck Institute for the Physics of Complex Systems in Dresden, and the Max Born Institute in Berlin, among others. The findings were published on November 21, 2025, in the journal Science Advances.
Utilizing ultrashort and intense X-ray pulses produced by accelerator-based free electron lasers (FELs), the researchers were able to observe how intense laser fields reshape molecules. The experiment took place at the Linac Coherent Light Source (LCLS) within the SLAC National Accelerator Laboratory, marking the first time such molecular dynamics have been directly imaged in real-time.
The research involved analyzing the X-ray diffraction patterns of C60 as it responded to strong infrared (IR) laser pulses. Two key parameters were extracted: the average radius (R) of the molecule and the Guinier amplitude (A), which is indicative of the strength of the X-ray scattering signal. This amplitude is proportional to the squared effective number of atoms in the molecule, providing insights into the fragmentation processes occurring during the experiment.
As the intensity of the laser varied, the researchers observed distinct stages of the C60 molecule’s response. At a low intensity of 1×10^14 W/cm², the molecule expanded before fragmenting. This initial fragmentation was indicated by a gradual decrease in the Guinier amplitude. At an intermediate intensity of 2×10^14 W/cm², the expansion was followed by a noticeable reduction in the X-ray imaged radius, signifying the scattering of smaller fragments. At the highest intensity of 8×10^14 W/cm², the molecule underwent rapid expansion, with a simultaneous decrease in the Guinier amplitude, suggesting that most outer valence electrons had been stripped away.
The theoretical model calculations conducted at the Max Planck Institute for the Physics of Complex Systems showed that while there were qualitative agreements with experimental findings at lower intensities, discrepancies arose at higher intensities. The model predicted oscillatory behavior in both radius and amplitude due to periodic “breathing” of the molecule, which was not observed in the experimental data. To improve the alignment of theoretical predictions with actual results, the researchers introduced an ultrafast heating mechanism, leading to better agreement with the experimental outcomes.
The study highlights the challenges of fully understanding multi-electron dynamics under intense laser fields, as a complete quantum mechanical treatment remains elusive. The X-ray movies created during this research serve as an excellent testbed for exploring fundamental quantum processes in increasingly complex molecular systems. Such insights pave the way for future advancements in controlling chemical reactions using laser fields.
This groundbreaking work not only enhances our understanding of molecular dynamics but also sets the stage for further research into the manipulation of chemical reactions through precise laser interactions. For more information, refer to the original 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.
