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Explore the cutting-edge field of ultrafast electron dynamics through this 49-minute physics lecture that examines how attosecond X-ray free electron lasers can probe electronic motion on femtosecond and sub-femtosecond timescales. Discover how the ultrafast motion of electrons serves as a fundamental component in photochemical processes and chemical reactions, with electronic rearrangement being the primary mechanism through which light energy is harnessed in photochemistry. Learn about the natural timescale for electronic motion, which is set by energetic splitting of electronic states on the scale of electron volts, resulting in few-to-sub femtosecond dynamics. Understand how short light pulses can excite small quantum systems to induce time-dependent oscillations in charge density, creating electronic wavepacket motion known as charge migration that occurs independently of nuclear motion. Examine how this initial purely electronic motion eventually couples to other system degrees of freedom, including nuclear motion and chemical dynamics, leading to charge localization and transfer across molecular bonds. Gain insights into the state-of-the-art Linac Coherent Light Source (LCLS), an X-ray free electron laser facility that produces high-brightness, ultrashort pulses with continuously tunable wavelengths across the x-ray regime. Discover recent developments in generating isolated, sub-femtosecond pulses from free electron lasers and their application in time-resolved measurements of ultrafast electron dynamics. Review specific research applications using sub-femtosecond XFEL pulses to study ultrafast charge dynamics in both core-excited and low-lying cationic molecular systems. Learn about early science efforts utilizing high repetition rates from the new LCLS-II superconducting accelerator to address problems in chemical and material science research.
