Electron motion is a key ingredient of chemical reactions. For small quantum systems, the natural timescale for such electronic motion is typically in the range of tens to hundreds of attoseconds. Consequently, the study of ultrafast electronic phenomena requires the generation of laser pulses shorter than 1 fs, and of sufficient intensity to drive multiple interactions with the target. Free Electron Lasers (FELs), such as the Linac Coherent Light Source (LCLS), are now able to achieve these conditions, allowing for the probing of electron dynamics on this natural time scale, elucidating the earliest processes involved in chemical change.
In my talk, I will present our first results demonstrating nonlinear spectroscopies such as pump/probe spectroscopy, and X-ray wave mixing making use of this unique source. We demonstrated the preparation of a coherent electronic wavepacket by driving stimulated X-ray Raman scattering. Combing attosecond X-ray pulses with an external laser field we are able to time-resolve the photoemission dynamics of core-level electrons in molecules. I will also present a first result in attosecond-pump/attosecond-probe spectroscopy.