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, Nice, France

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

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

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

simulation: 100ps & 1.25mdeg conv. experiment: InSb 111, 10mJ/cm 2 Time-resolved Bragg Diffraction: Coherent Acoustic Phonons Reis et al. Phys Rev. Lett.(86) 2001D.A. Reis et al.

simulation: 100ps & 1.25mdeg conv. experiment: InSb 111, 10mJ/cm 2 Time-resolved Bragg Diffraction: Coherent Acoustic Phonons Reis et al. Phys Rev. Lett.(86) 2001D.A. Reis et al.

GaAsAlGaAs GaAs expansion compression AlGaAs Electronic, Thermal and Mechanical Properties of thin films and interfaces GaAs Al 0.3 Ga 0.7 As 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, (2005) D.A. Reis et al.

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.

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

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

Femtosecond Optical Pump-Probe anharmonicity or electronic softening? (Fahy and Reis PRL , 2004) Fritz et al., U. of M. a a a Coherent A 1g Mode is strongly softened and chirped. Peierls Distorted D.A. Reis et al.

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

30 GeV 80 fs 10 10, 30 GeV e-/pulse: 80 fs, 9 keV, 10 6 x rays/pulse SPPS, LINAC based femtosecond x-rays for Materials research and LCLS R&D.

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

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

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 , 2005 (fiber transport) S. H. Lee et al. Opt. Lett., 29(22):2602–2604, 2004

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

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

x0x0 D.M.Fritz Submitted to Science Measured Interatomic Potential of Highly Photoexcited Bismuth D.A. Reis et al.

Unobserved! Recoules et al. PRL 96, (2006) Lee et al, GaAs TDS Momentum Resolved Experiments with Diffuse Scattering Squeezing, phase transitions, anharmonic decay, thermalization… Biswas and Ambegaokar PRB 26,1980 (1982) D.A. Reis et al.

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

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

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

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.