The response of molecules to sequences of ultrafast optical pulses ranging from the infrared to the soft and hard x-ray regimes provides novel windows into elementary molecular events and electronic and nuclear motions. Recent developments in this field involving the use of broadband x-ray pulses and entangled photons will be surveyed. New x-ray light sources are capable of triggering valence electron motions impulsively by a stimulated resonant Raman process via core excitations and monitoring them with high temporal and spatial resolution. Attosecond x-ray pulses can probe quantum coherence and correlations of valence electron and hole pairs, in an analogous manner to the way vibrational motions are investigated using femtosecond Raman techniques in the visible regime. By creating multiple core holes at controlled times and locations it becomes possible to study the dynamics and correlations of valence electrons as they respond to core hole perturbations. Stimulated x-ray Raman spectroscopy (SXRS) signals thus reveal the dynamics of valence electronic wave packets prepared and detected in the vicinity of a selected atom. Applications will be presented to energy transfer in porphyrin aggregates, long-range biological electron transfer in Azurin and multidimensional electron diffraction. The temporal and spectral resolution of femtosecond stimulated Raman spectroscopy (FSRS) techniques will be discussed with applications to conical intersections in Uracil and to photoactivated DNA repair. Entangled photons provide novel nonlinear spectroscopic probes of excitation energy transfer and charge separation processes in chromophore aggregates. Quantum spectroscopy signals utilize the quantum nature of the optical field by varying parameters of the photon wavefunction rather than classical field envelopes. It will be demonstrated how the unusual spectral and temporal characteristics of entangled photon pairs combined with interferometric detection make it possible to manipulate and control two photon absorption and Raman signals and extract information not available with classical light.

<b>Award Address</b> (Ahmed Zewail Award in Ultrafast Science and Technology sponsored by the Ahmed Zewail Endowment Fund established by Newport). Multidimensional electronic and vibrational spectroscopy of molecules using attosecond X-ray pulses and quantum light

249th National Meeting (2015)

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Award Address (Ahmed Zewail Award in Ultrafast Science and Technology sponsored by the Ahmed Zewail Endowment Fund established by Newport). Multidimensional electronic and vibrational spectroscopy of molecules using attosecond X-ray pulses and quantum light