Localized core four-wave mixing buildup on the X-ray spectrum of chemical species

X-ray absorption spectroscopy (XAS) is an element-specific probe of the local structural environment of a molecule. The X-ray spectra include extended X-ray absorption fine structures (EXAFS), which give information on the bond-lengths, and X-ray absorption near edge structures (XANES), which give information on the atomic geometry and oxidation state. The X-ray spectra obtained in XAS provide a unique fingerprint of the state of a particular molecule. The advance on ultrabright femtosecond X-ray pulses provided for instance by X-ray free-electron lasers (FEL) open capabilities for directly watch structural changes and atomic motions during chemical and biochemical reactions or physical processes, in their natural spatial and temporal time scales.

We exploit the random phase characteristics of trains produced in X-ray sources and propose a core coherent nonlinear technique to efficiently produce spectrally selected X-ray radiation at the specific position of a target molecule. In the intense regime, our method entails a new valuable tool in the frame of X-ray spectroscopies, with potential for applications in biology, chemistry, medicine and materials sciences. At low-dose, using hard X-rays as in medical imaging, our approach is well suited to a large number of medical applications, since a well-tuned laser may selectively excite and detect or so cancel the effect of specific molecules in pathogens such as viruses, bacteria or cancer cells.

The results have been recently published in the article entitled: Localized Core Four-Wave Mixing Buildup in the X-ray Spectrum of Chemical Species in the Journal of Physical Chemistry Letters. The reference of the article is:

C. Serrat, "Localized Core Four-Wave Mixing Buildup in the X-ray Spectrum of Chemical Species", J. Phys. Chem. Lett. 12, 1093−1097 (2021).