European XFEL X-rays reveal atom-specific energy shifts in molecule in trillionths of a second
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European XFEL's ultrafast X-ray pulses recorded how 3-fluoropyridine redistributes energy after absorbing light, showing that individual atoms capture different stages of the transformation. Fluorine atoms indicated vibrational relaxation while nitrogen atoms reflected electronic redistribution, revealing the molecular dance in trillionths of a second. The technique, detailed in a study published July 29, offers real-time observation of light-driven chemistry at the atomic scale.
Molecule's Light-Driven Transformation
The team studied 3-fluoropyridine, a ring-shaped molecule containing nitrogen and fluorine. After a UV laser pulse, its electrons entered an excited state, causing the molecule to bend out of its flat shape and pass through a conical intersection — a fleeting point where electronic and nuclear motions couple strongly. The molecule then returned to its ground state, converting excess electronic energy into vibrations that propagated through the structure in trillionths of a second.
Divergent Atom Signals
Fluorine atoms acted as clear markers of vibrational relaxation, while nitrogen atoms — more directly involved in the excitation — reflected both electron redistribution and structural changes. 'Not every atomic site tells the same story,' said co-author Antonio Picón of ICMM-CSIC. The European XFEL's femtosecond X-ray pulses distinguished these site-specific signals, revealing how energy transits between different parts of the molecule.
What's Next
The team expects to apply the method to complex biomolecules like DNA to study how genetic material withstands light damage. It remains unclear whether the technique can resolve even faster electronic dynamics at sub-femtosecond timescales.
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European XFEL X-rays reveal atom-specific energy shifts in molecule in trillionths of a second
