More than a decade ago: Accelerator development enabled visionary science

1. More than a decade ago: • Accelerator development enabled visionary science • probe-before-destroy • Haidu et al. • soft x-ray magnetic holography • Wang, et al. PRL (2013)

2. Today: We need the complementarity of x-rays & electrons • to access to the “Ultrafast” & “Ultrasmall” • FePt • heat sink • 2nm • Goal: understand & control materials processes • probes electrons & spins • probes lattice • G. Bertero (WD Corp.) • soft x-ray magnetic holography • nano-UED • Xiang, et al. SLAC report (2014) • Wang, et al. PRL (2013)

3. X-rays or electrons? We need both! • Electrons: • can be manipulated by electric & magnetic fields (microscopy) but have <10nm coherence lengths. • X-rays: • Fully coherent beams offer new opportunities for holographic imaging. Soft x-ray resonant inelastic cross sections are comparable to those of electrons, elastic cross sections are much lower. • R.Henderson,Quarterly Reviews of Biophysics 28 (1995) 171-193.

4. The Future of Electron Scattering & Diffraction • Opportunities for Ultrafast Science • Key Breakthrough Science Opportunities and Challenges • Atomic Scale Molecular Processes • Photonic Control of Quantum Materials • Energy Transport at the Nanoscale • Mesoscale Materials and Phenomena • Evolving Interfaces, Nucleation, and Mass Transport • DOE Basic Energy Sciences Needs Workshop Report (2014)

5. The Future of Electron Scattering & Diffraction • How do we get there? • UEM • User Facility • Nano-UED • User Facility • Ultrafast • Electron • Microscopy • Ultrafast • Electron Diffraction • DOE Basic Energy Sciences Needs Workshop Report (2014)

6. Controlling processes on the level of electrons: • Non-Born-Oppenheimer dynamics in molecules • requires sub-100 fs with unfocused electron beam at high repetition rates • (UED) • Ben-Nun and Martinez, Chem. Phys. 259, 237(2000) • Absorption triggers coupled ultrafast motion of nuclei and electrons, hard to model • Born-Oppenheimer violation provides fast funnels for steering energy into particular channel • M. Centurion Lab • U. Nebraska • Aligned CF3I • Guehr, et al.

7. Opportunities for Ultrafast Materials Science • nanoscale energy transport • requires sub-100 fs with focused electron beam at high repetition rates • (nano-UED) • nanoscale mechanisms of phase transitions • photonic control of quantum materials

8. Imaging of Nanoscale Processes • Phase transitions: diffusionless vs. mass transport • requires single-shot imaging • (10ps - 10 nm UEM) • Biological processes • Carbon fixation by bacterial carboxysomes

9. Early Science Opportunities with UED • Gas phase chemistry (sub-100fs & 100μm beam size): Experimental setup is still under development (requires isolation of gun and sample vacuum). • UEM • User Facility • Materials science will initially be limited by available samples: • etching, exfoliation, sample growth of ~ 100μm free standing films needs to be developed) • Nano-UED • User Facility • Ultrafast • Electron • Microscopy • Development of laser-electron cross correlation schemes: • use laser-induced space charge • electron beam induced dynamics • photo-induced electron-lattice coupling in wide-bandgap oxides • Ultrafast • Electron Diffraction

10. Early Science Opportunities with UED • Gas phase chemistry (sub-100fs & 100μm beam size): Experimental setup is still under development (requires isolation of gun and sample vacuum). • First results (A. Reid, R. Li, P. Musumeci) • Materials science will initially be limited by available samples: • etching, exfoliation, sample growth of ~ 100μm free standing films needs to be developed) • Development of laser-electron cross correlation schemes: • use laser-induced space charge • electron beam induced dynamics • photo-induced electron-lattice coupling in wide-bandgap oxides • Measurement of single-shot electron diffraction from a 40nm FeRh film epitaxially grown on 10 nm MgO IBAD deposited on 100nm SiN.