Early Science

Early Science (DREAM)

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Early Science (NAMASTE)

The new designed Time-resolved atomic, Molecular and Optical science (TMO) instrument, will start RUN 18 with Early Science Experiments which are open to the community. The Early Science will be lead by Ming-Fu Lin, James Cryan and Peter Walter with the expectation of strong participation from key members of the AMO community. 

The following Early Science Experiments are scheduled:

  • LW05 - High Field Physics at TMO:To finalize the transition from commissioning to operation, we have foreseen High Field Physics (HFP) experiments. With the new hardware TMO will reach irradiation levels around 10^19 W/cm². Compared to previous efforts on this topic, this opens new routes to characterizing highly transient ionic atomic and molecular systems. We propose to perform resonant double core hole (DCH) studies in Ne and N2O. This will capitalize on scientific results that LCLS enabled in 2009, i.e. DCH spectroscopy on atomic systems, benchmark the irradiation achieved under the new conditions and then expand the Resonant-DCH scheme to molecules. Concluding we will perform non-sequential ionization experiments by investigating two photon absorption and two photon non-sequential double ionization in Ne.​
  • LW06 - Chemical Dynamics in Ultrafast Molecular Dissociation Of Nitrous Oxide: The aim of the proposed experiment is to monitor fundamental chemical processes at their inherent time scale from a few to tens of femtoseconds, not only resolving the energy but also the symmetry evolution of electron orbitals. We seek to directly and site-specifically reveal ultrafast chemical dynamics during molecular restructuring of the atmospherically important nitrous oxide (N2O). Therefore, we plan to efficiently dissociate N2O with an X-ray pulse at 430 eV followed by another time shifted X-ray pulse at 440 eV which monitors the chemical (spectral) changes with femtosecond resolution via investigation of the K-Shell photoelectron emission with angular resolution. ​
  • LW08 - UV-driven Photochemistry in NO2: NO2​ is well-known to photodissociate upon excitation <400 nm. After photoexcitation to the A state, it relaxes within 200 fs through a conical intersection back to its ground state mainly through O-N-O bending. It undergoes ON-O dissociation in the ground state within <1 ps. The dissociating molecules should localize almost all of the photoabsorbed energy in their asymmetric stretch degree of freedom. We will investigate the coherent nature of this dissociation process with time-resolved x-ray photoelectron spectroscopy (XPS) and x-ray absorption spectroscopy (XAS) from total ion yield measurements at the nitrogen and oxygen K-edges. Both methods can be expected to be sensitive to bond dissociation processes. This experiment will demonstrate our readiness to perform time-resolved photochemistry experiments in advance of User experiments. ​
  • LW07 Channel Coupling in Attosecond Photoemission: Many-electron correlations, relativistic effects, and relaxation effects of the ionic core in the ionization process need to be taken into account when considering ionization on the attosecond timescale. We propose to use angular streaking of Xenon 3d photoelectrons (3d5​/2​: Ip​​ = 677 eV, 3d3​/2​: Ip​​ =  689 eV). Calculation and measurements show interesting features in the 3d-subshell photoionization cross section and anisotropy parameters. The 3d-subshell electrons show channel coupling features, i.e. electron correlation effects, that cause interaction between the two continuum channels. In the cross sections, these show up as a second resonance in the 3d5​/2​ cross-section corresponding to the 3d3​/2​ ionization potential. We propose to measure the relative delay between the two lines in the 3d-doublet, and fully characterize the measured electron wavepackets using the reconstruction technique developed and experimentally demonstrated in experiments before. This provides a measurement to help resolve electron correlation effects with attosecond precision.

If you have further questions please do not hesitate to reach out to Peter Walter (pwalter@slac.stanford.edu). Please keep in mind that the overall participants per experiment are limited and only confirmed participants will be allowed to participate directly in the beamtime.

The latest version of the Run 18 schedule can be found here (Link; https://lcls.slac.stanford.edu/sites/lcls.slac.stanford.edu/files/LCLS_Run18_Schedule.pdf)