MOZD3
Stanford University, Stanford, California, USA
SLAC, Menlo Park, California, USA
We report the generation of GW-level attosecond pump/probe pulse pairs with tunable sub-femtosecond delays at the Linac Coherent Light Source (LCLS). The attosecond 370 eV pump pulse is first generated via the Enhanced Self-Amplified Spontaneous Emission (ESASE) method, then the attosecond 740 eV probe pulse is produced by re-amplifying the electron beam microbunching after the magnetic chicane. Due to the harmonic amplification, the minimal delay between pump-probe pulse pairs (limited by slippage between the light field and the electron bunch) can be shorter than 1 femtosecond. We use the angular streaking technique to measure temporal delays between pump/probe pulse pairs at multiple beamline configurations. When the delay chicane is turned off, the averaged delay is increased by ~150 attoseconds by adding one undulator module for probe pulses. Long delays can be set up by turning the delay chicane on. These experimental results are in agreement with start-to-end XFEL simulations. Looking toward future experiments, our sub-femtosecond pump/probe technique can be applied to observe electronic charge dynamics in molecular systems.
