Attosecond spectroscopy of liquids and solutions

The majority of chemical reactions occur in liquids, yet accessing their ultrafast electronic dynamics has long been hindered by limited temporal resolution. Recent advances have brought attosecond spectroscopy into the liquid phase, enabling new insights into solvation and electronic processes. This talk highlights major breakthroughs, starting with the first attosecond time-resolved measurements on liquid water, revealing solvation-induced photoionization delays of 50–70 attoseconds compared to isolated molecules [1]. These delays were linked to local electronic structure changes, confirming the ability to isolate electronic dynamics in solution. Cluster studies showed how electron-hole delocalization evolves with size and partially localizes in bulk-like systems, tying delays to hole structure [2]. TRPES of cis-stilbene captured coherent vibrational motion in both gas and liquid phases, showing such coherence survives even in fluctuating environments [3]. Water-window X-ray absorption spectroscopy using microjets revealed femtosecond proton transfer and electronic rearrangements with element and site specificity—critical for studying non-adiabatic and prebiotic chemistry [4]. In pyrazine, attosecond methods showed that electronic dynamics initiated by conical intersections is rapidly quenched in solution within 40 fs, highlighting solvation’s damping role [5]. These results show attosecond spectroscopy cleanly separates ultrafast electronic motion from slower structural changes, offering transformative access to chemical dynamics in liquids—the true native phase of chemistry.

References

[1] Jordan et al., Science 369, 974 (2020)

[2] Gong et al., Nature 609, 507 (2022)

[3] Wang et al., Nat. Chem. 14, 1126 (2022)

[4] Yin et al., Nature 619, 749 (2023)

[5] Chang et al., Nat. Phys. 21, 137 (2025)