Ultrafast X-ray Scattering from Coherent Phonons

1. Ultrafast X-ray Scattering from Coherent Phonons David A Reis University of Michigan, Department of Physics International Workshop on Energy Conversion and Information Processing Devices September 26, 2006. Nice, France

2. How do we understand the interaction of an ultrafast laser pulse with condensed matter? ? D.A. Reis et al.

3. High Brightness, Picosecond X-rays D.A. Reis et al.

4. Laser-pump–X-ray-probe Ge 400 Bragg reflex. 280 µm thick,vs=5000 m/s 1st echo synchrotron Laser • Resolution limited by the bunch duration (or the timing jitter) • Arbitrary pump-probe delay (NOT limited by bunch separation) D.A. Reis et al.

5. Time-resolved Bragg Diffraction: Coherent Acoustic Phonons simulation: 100ps & 1.25mdeg conv. experiment: InSb 111, 10mJ/cm2 D.A. Reis et al. Reis et al. Phys Rev. Lett.(86) 2001

6. Time-resolved Bragg Diffraction: Coherent Acoustic Phonons simulation: 100ps & 1.25mdeg conv. experiment: InSb 111, 10mJ/cm2 D.A. Reis et al. Reis et al. Phys Rev. Lett.(86) 2001

7. Al0.3Ga0.7As GaAs AlGaAs GaAs AlGaAs AlGaAs expansion expansion compression compression expansion GaAs Electronic, Thermal and Mechanical Properties of thin films and interfaces • Deformation potential and thermal expansion. • Free carrier absorption • Electron-phonon • Boundary resistance (Kapitza) • thermal conductivity and diffusivity. • Superlattices and folded phonons S.H. Lee et al.,PRL 95, 246104 (2005) D.A. Reis et al.

8. Fluence dependence Shows strong saturation (filling gamma valley) Early times deformation potential dominates. non-impulsive component to strain (Auger heating) Long times, see heating and cooling of substrate and film through shift in Bragg peak due to thermal expansion in preparation D.A. Reis et al.

9. Coherent Control of Pulsed X-ray Beams —forward —deflected laser M.F. DeCamp et al., Nature 413, 825 2001 Ambipolar diffusion of dense e-h plasma M.F. DeCamp et al., Phys. Rev. Lett. 91, 165502, 2003.

10. a a a Bismuth Structure Sensitive to Electronic State Peierls Distortion Density Dependent Potential Energy (Along Trigonal Direction) What can we learn about interatomic potential through ultrafast optical and x-ray experiments? D.A. Reis et al.

11. a a a Femtosecond Optical Pump-Probe Peierls Distorted Fritz et al., U. of M. Coherent A1g Mode is strongly softened and chirped. anharmonicity or electronic softening? (Fahy and Reis PRL 93 109701, 2004) D.A. Reis et al.

12. coherent control of phonon amplitudeat fixed carrier density pump1 pump2 chirp independent of phonon amplitude ultimately optical data cannot measure atomic positions Murray et al. PRB 72, 060301 (R) 2005. D.A. Reis et al.

13. SPPS, LINAC based femtosecond x-rays for Materials research and LCLS R&D. 30 GeV 80 fs 1010, 30 GeV e-/pulse: 80 fs, 9 keV, 106 x rays/pulse

14. Optical pump-probe and APSjitter << pulse duration system response impulse delayed probe pulse t SPPS (and future LCLS)jitter >> pulse duration system response impulse time D.A. Reis et al.

15. Single-Shot EOS Data at SPPS (100µm ZnTe) D.A. Reis et al. A. Cavalieri et al., Phys. Rev. Lett. 94 144801, 2005

16. Electron beam–X-ray beam timing correlation: EOS and “Melting” EOS and Melting 60 fs, likely resolution limited. A. Cavalieri et al., Phys. Rev. Lett. 94 144801, 2005 (fiber transport) S. H. Lee et al. Opt. Lett., 29(22):2602–2604, 2004

17. Timing jitter in electron beam used for random sampling Movie of Data here: D.A. Reis et al.

18. x a a a f x(t),n(t) Ultrafast measurement of atomic displacements N=12463 D.A. Reis et al.

19. x0 Measured Interatomic Potential of Highly Photoexcited Bismuth D.M.Fritz Submitted to Science D.A. Reis et al.

20. Lee et al, GaAs TDS Unobserved! Momentum Resolved Experiments with Diffuse Scattering Squeezing, phase transitions, anharmonic decay, thermalization… Biswas and Ambegaokar PRB 26,1980 (1982) Recoules et al. PRL96,055503 (2006) D.A. Reis et al.

21. Phonon Dispersion in Bi Murray et al. submitted to PRB 2006 D.A. Reis et al.

22. N S N S N S N S N S N S N S N S N S N 2 compressors S N S N S N S N S N S N S N S N S one undulator LCLS Future of Ultrafast X-rays, commissioning mid 2008 1.5-15 Å World’s first x-ray free electron laser D.A. Reis et al.

23. Future picosecond X-rays at the APS?Obtaining short x-ray pulse from a “long” electron bunch RF deflecting cavity RF deflecting cavity Electron trajectory X-ray compression in asymmetric-cut crystals ∆l Collimating mirror Radiation from tail electrons Undulator Radiation from head electrons Input x-ray pulse >> diffraction limited size and natural beamsize A. Zholents D.A. Reis et al.

24. Acknowledgments Students Adrian Cavalieri, David Fritz, Soo-Heyong Lee, Yu-Miin Sheu APS Sector 7 Staff Dohn Arms, Eric Dufresne, Eric Landahl, Don Walko SPPS collaboration (~13 institutions/50 scientists, J. Hastings spokesperson ) and… B. Adams, P. Bucksbaum, R. Clarke, M. DeCamp, R. Goldman, R. Hegde, B. Lings, R. Merilin, E. Murray, S. Fahy, M. Reason, M. Swan, J. Wahlstrand, J. Wark, …et al. DOE BES AMOS Program andStanford PULSE Center NSF FOCUS PFC D.A. Reis et al.