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Femtosecond electron diffraction: Heralding the era of atomically-resolved dynamics Germn Sciaini Max Planck Research Department for Structural Dynamics, Center for Free Electron Laser Science, DESY & Physics Department, University of

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Femtosecond electron diffraction: Heralding the era of atomically-resolved dynamics

Germán Sciaini

Max Planck Research Department for Structural Dynamics, Center for Free Electron Laser Science, DESY & Physics Department, University of Hamburg

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FED – similar effective brightness to 4th generation fs X-ray sources 200-keV FED setup Femtosecond electron diffraction (FED) layout LCLS European XFEL

Ultrafast Structural Dynamics

For recent advances in the field, see:

  • G. Sciaini and R.J.D. Miller. Rep. Prog. Phys. 74, 096101

(2011).

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DC compact e-guns 200-300 fs 108-109 ph/pulse New DC e-gun designs 100-300 fs 109-1010 ph/pulse. RF-compression e-guns ~sub-100 fs (250 fs) 1010-1011 ph/pulse Relativistic e-guns ~sub-100 fs (200 fs) 1010-1012 ph/pulse

FED fs X-ray

SLS—3rd generation LS, slicing 200 fs 300 ph/pulse Plasma sources 100 fs 103 ph/pulse. 4th generation light sources. sub-100 fs (100 fs) 1012 ph/pulse

For recent advances in FED see:

  • G. Sciaini & R.J.D. Miller. Rep. Prog. Phys. 74 096101 (2011).

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Major advance over conventional streak camera technologies.

Hebeisen, Sciaini et al. Opt Express 16, 3334 (2008)

Ponderomotive force:

Ponde

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Single shot versus reversible FED experiments

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FED experiments under nonreversible conditions “single shot” Sample is moved between shots

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Over a century of theories to explain “Melting”

Sutherland W. Philos. Magazine (1891) 32:194, 31-43.

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Heterogeneous-- Surface Homogeneous--Bulk 3 ps 5 ps 4 ps 20 ps 100 ps

Lin et al. J. Phys. Chem. C 114, 5686 (2010)

500 ps

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Optical phonon period!

  • G. Sciaini et al., Nature 458, 56 (2009).

In news & views, Nature 458, 42 (2009).

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Sciaini et al. irradiate crystalline bismuth with ultrashort bursts of electrons to monitor the emergence of atomic disorder during laser-induced melting. The images show electron-diffraction patterns observed before (a) and after (b) laser excitation. Atomic disorder emerges in about 200 femtoseconds (0.2 picoseconds). (Modified from a graphic by J. Harms.)

  • A. Cavalleri. Nature (news & views) 458, 42 (2009)

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FED experiments under reversible conditions

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Shear mode detection becomes trivial

Full Characterization of Mechanical Properties of Nanomaterials

Harb et al. Phys. Rev. B 79, 094301 (2009)

DT = 320K Unit cell changes ~ 10-3 Å detectable.

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http://www.physnet.uni-hamburg.de/iap/group_g/F_Praktikum/Rastertunnelmikroskopie/

Θ ~ 10o

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STM image – real space Reciprocal space

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Fluence: 2.4 mJ/cm2 DT(pump) ~ 90 K CDW_movie

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Initial amplitude of the periodic lattice distortion ~ 0.1 Å. Atomic displacements ~ 0.02 Å

Movie_real Movie_recip

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Submitted to Nature.

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Chollet et al., Science 307, 86 (2005).

Insulator-to-Metal phase transition in (EDO-TTF)2PF6.

In collaboration with:

  • Prof. Shin-ya Koshihara
  • Prof. Ken Onda

Tokyo Institute of Technology

  • Prof. Hideki Yamochi

Kyoto University 100-nm thick samples 100-keV FED setup

(EDO-TTF)2PF6

(TMTSF)2PF6 First organic superconductor

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  • M. Gao, et al., submitted to Nature.
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Sample degradation – diffracted intensity vs. #

  • f laser shots; @ (a) 1 kHz; (b) 10 Hz.

Organic samples: a challenging problem

100 nm thick samples, images – polarized light microscope

(a) (b)

Masked dynamics due to accumulative heating @ 1 kHz

Gao M, Jean-Ruel J et al., Opt. Express 20, 12048 (2012).

10 Hz 200000 e/pulse 280 um spot size IRF – 0.4 ps (FWHM)

  • M. Gao, et al., submitted to Nature
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Time-resolved studies implementing a recently developed Ultrabright FED setup @ 10 Hz

Time-dependent photo-induced differential intensity changes Thermal phase transition Over 200 reflections showing time-resolved Intensity changes beyond SNR.

  • M. Gao, et al., submitted to Nature.
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Unpublished results Coming soon…

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Acknowledgments

Toronto/Hamburg

  • Prof. R.J.Dwayne Miller

Present members/Toronto

  • Dr. Gustavo Moriena

Hubert Jean-Ruel Ray Gao Lai Chung Liu Past members

  • Prof. Ralph Ernstorfer
  • Dr. Maher Harb
  • Dr. Thibault Dartigalongue
  • Dr. Christoph Hebeisen
  • Dr. Sergei Kruglik
  • Dr. Cheng Lu
  • Dr. Ryan Cooney

Canadian Light Source

  • Dr. Mark de Jong
  • Dr. Jonathan Stampe

Tokyo Institute of Technology

  • Prof. Shin-ya Koshihara
  • Prof. Ken Onda

Kyoto University

  • Prof. Hideki Yamochi

& co-workers. Wisconsin Madison

  • Prof. Max Lagally
  • Prof. Mark Eriksson

Weina Peng U of Konstanz

  • Prof. Jure Demsar

Maximilian Eichberger Hanjo Shäfer EPFL

  • Dr. Helmuth Berger

Universität Duisburg-Essen

  • Prof. Michael Horn-von Hoegen
  • Dr. Frank Meyer zu Heringdorf

Thomas Payer

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Thank you for your attention!

Thank you!