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By using theoretical and computer-based models, a team of scientists has demonstrated that extremely short X-ray pulses can trigger the motion of electrons in benzene molecules1.

This motion drives many important physical, chemical and biological reactions in nature. Knowledge of such a motion in benzene molecules might open up new ways to probe and understand such reactions.

Moving electrons inside molecules have magnitude and direction that are known as electronic flux. However, there is no way to probe electronic flux directly in experiments. In search of a method, an international team including Gopal Dixit, a physicist from the Indian Institute of Technology in Mumbai, proposed models of a two-part experiment.

In that experiment, they proposed inducing the motion of electrons in benzene molecules by exposing them to extreme ultraviolet light. They then showed that it is possible to image the electrons’ motion using ultra-short X-ray pulses.

The researchers made movies of the charge migration and electronic fluxes of valence electrons of benzene molecules. They observed that the flow of electrons was faster around the central carbon atoms of benzene.

Since this research deciphers how electrons flow in molecules such as benzene, it will help understand similar processes in other molecules, they say.

This understanding will help develop new ways to tweak properties of materials, eventually allowing the design of smarter solar cells and other tiny electronic devices, says Dixit. “Next, we aim to embark on experiments that would pinpoint chemical processes that underlie vision,” he said.


1. Hermann, G. et al. Probing electronic fluxes via time-resolved X-ray scattering. Phys. Rev. Lett. 124, 013002 (2020)