Liquid water is essential for the existence of life. Despite enormous efforts, there is still an incomplete understanding of the interaction of water molecules with each other and with ions.1 In this work, we present a combined study of liquid water and aqueous solutions utilizing state-of-the-art high harmonic and high-resolution Resonant Inelastic X-ray Scattering (RIXS) spectroscopy in liquid phase which may help to corroborate current understanding. High harmonic generation (HHG) enabled the study of electronic dynamics on the attosecond time scale.2 In conventional HHG from inversion-symmetric gases, the laser pulses give rise to only odd harmonics. Adding the second harmonic of the fundamental pulses perturbs the electron’s trajectories, alters the interference between different cycles and thereby permits the emission of even harmonics. Thus, two-color experiments of this type have enabled the possibility of studying and controlling the HHG process in fine details [3]. Here, we show that this approach can be extended to the liquid phase using the flat micro-jet [4], to elucidate electronic processes in liquids in real time. Preliminary analyses show that the relative phase between the odd and even harmonics in liquids is distinctively different from the gas phase see Fig. 1c, suggesting a complex mechanism compared to well-known gas phase behaviour. This two-color approach allows mapping the dynamical electronic properties of the aqueous solutions with unprecedented time resolution. Our recent high-resolution RIXS results reveal strong perturbation of the electronic structure induced by the presence of specific ions, ranging from weak to strong hydrated ions. There seems to be ion specific influence mirrored on the orbitals of liquid water. We anticipate that our works would contribute in elucidating the water–water and water–ion interaction on the molecular level.

Probing liquid water and aqueous solution with two-color high-harmonic and X-ray spectroscopy

2019 Fall National Meeting

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