Attosecond Science Campaign

Realtime Observation of Ultrafast Electron Motion

This is the LCLS lead campaign in attosecond science. We will perform measurements of attosecond electron dynamics and subsequent coupling to nuclear motion using the soft X-ray attosecond capabilities of the LCLS. The continuous tunability and orders-of-magnitude pulse energy increase (compared to any previous attosecond source) produced by enhanced SASE operation at the LCLS enable a suite of nonlinear spectroscopies which are unavailable elsewhere. We attempt to make use of these unique capabilities to perform measurements demonstrating the control and observation of coherent electronic motion on its natural attosecond timescale, and explore how it affects the subsequent motion of the nuclei to drive chemical change. This campaign will provide pioneering insights into the coherent motion of electrons and how this drives chemical change, producing incisive X-ray observables against which theory can be directly tested on an unprecedented level of detail with particular emphasis on the atomic site-specific information content of X-ray transitions.

Results

Effect of the shot-to-shot variation on charge migration induced by sub-fs x-ray free-electron laser pulses:
We demonstrated theortically that the damping of the charge migration induced by 260 eV pulses in p-aminophenol due to the shot-to-shot variation of pulses generated by an XFEL is negligible in comparison to the natural damping due to the intrinsic fluctuation of the initial molecular geometry. This is an important result to validate our methodology for using attosecond XFELs to probe ultrafast charge motion. 

Gilbert Grell, Zhaoheng Guo, Taran Driver, Piero Decleva, Etienne Plésiat, Antonio Picón, Jesús González-Vázquez, Peter Walter, Jonathan P. Marangos, James P. Cryan, Agostino Marinelli, Alicia Palacios, and Fernando Martín
Phys. Rev. Research 5, 023092 (2023)