Electronic dynamics in liquids are of fundamental importance, but time-resolved experiments have so far remained limited to the femtosecond time scale. We report the extension of attosecond spectroscopy to the liquid phase. We measured time delays of 50 to 70 attoseconds between the photoemission from liquid water and that from gaseous water at photon energies of 21.7 to 31.0 electron volts. These photoemission delays can be decomposed into a photoionization delay sensitive to the local environment and a delay originating from electron transport. In our experiments, the latter contribution is shown to be negligible. By referencing liquid water to gaseous water, we isolated the effect of solvation on the attosecond photoionization dynamics of water molecules. Our methods define an approach to separating bound and unbound electron dynamics from the structural response of the solvent.

Efficient excitation of Fano resonances in plasmonic systems usually requires complex nano-structure geometries and some degree of symmetry breaking. However, a single-layer concentric core-shell particle presents inherent Fano profiles in the scattering spectra when sphere and cavity modes spectrally overlap. Weak hybridization and proper choice of core and shell materials gives place to strong electric dipolar Fano resonances in these systems and retardation effects can result in resonances of higher multipolar order or of magnetic type. Furthermore, proper tailoring of illumination conditions leads to an enhancement of the Fano resonance by quenching of unwanted electromagnetic modes. Overall, it is shown that single layer core-shell particles can act as robust Fano resonators.

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We show how to emulate a conventional pump-probe scheme using a single frequency-chirped ultrashort UV pulse to obtain a time-resolved image of molecular ultrafast dynamics. The chirp introduces a spectral phase in time that encodes the delay between the pump and the probe frequencies contained in the pulse. By comparing the results of full dimensional ab initio calculations for the H 2 + molecule with those of a simple sequential model, we demonstrate that, by tuning the chirp parameter, two-photon energy-differential ionization probabilities directly map the wave-packet dynamics generated in the molecule. As a result, one can also achieve a significant amount of control of the total ionization yields, with a possible enhancement by more than an order of magnitude.

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