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Matthias Uiberacker

Sampling electron dynamics in atoms in real time with sub-femtosecond resolution. Matthias Uiberacker. Prof. Ferenc Krausz. Max-Planck-Institut für Quantenoptik Garching, Germany. Dept. f. Physik, Ludwig-Maximilians-Universität München, Germany. Institut für Photonik

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Matthias Uiberacker

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  1. Sampling electron dynamics in atoms in real time with sub-femtosecond resolution Matthias Uiberacker Prof. Ferenc Krausz Max-Planck-Institut für Quantenoptik Garching, Germany Dept. f. Physik, Ludwig-Maximilians-Universität München, Germany Institut für Photonik Technische Universität Wien Wien, Austria Brijuni Conference, 31. August 2006, Brijuni Islands, Croatia

  2. [nanometers] 0.1 0.2 0.3 0.0 0.4 attosecond physics aims at gaining insight into the motion of electrons on atomic scales e- e- real-time observation direct control & of electronic motion in atoms, molecules, solids and plasmas

  3. the microcosm: imaging in space and time space (m) atoms in 10-9 electrons in microscopy, diffraction molecules & solids molecules atoms 10-12 attophysics time (s) nuclear structure & dynamics 10-18 10-15 10-12 10-15 attosecond metrology femtosecond metrology

  4. high–speed photography of microscopic processes: time–resolved pump-probe spectroscopy

  5. a sampling system with sub-fs resolution • utilizing pump/probe techniques • pump pulse and probe pulse need to be short enough to freeze the motion of electrons • ultrashort visible laser pulses are close to the wavecycle-limit of pulse duration (1-3fs). • ..but, can be used to produce shorter (sub-fs) xuv pulses (high harmonic generation) • efficiency for 2 sub-fs xuv pulses is not sufficient yet • what to do?

  6. using the electric field of laser pulses for probing with sub-fs resolution a(t) E(t) = a(t)cos(ωLt + φ) T0  2.5 fs T0 /4  625 as (@ 0  0.75 µm)  requires stabilization and control of carrier-envelope phase in combination with a weak sub-fs xuv pulse -> pump/probe measurements with sub-fs resolution!

  7. waveform-controlled few-cycle light opens the door to steering & capturing electrons on an attosecond timescale ultrabroadband dispersion control with chirped multilayers stabilization of the frequency comb of a mode-locked laser T. W. Hänsch et al., 1997, 1999 H. Telle et al. Appl. Phys. B 69, 327 (1999) D. Jones et al., Science288, 635 (2000) R. Szipöcs, K. Ferencz, Ch. Spielmann, F. Krausz Opt. Lett.19, 201 (1994) A. Baltuska, T. Udem, M. Uiberacker, M. Hentschel, E. Goulielmakis, C. Gohle, R. Holzwarth, V. Yakovlev, A. Scrinzi, T. W. Hänsch, F. Krausz, Nature421, 611 (2003)

  8. xuv/x-ray radiation from strongly driven atoms few-femtosecond, few-cycle laser pulse λL 750 nm Tp= 5 - 6 fs Wp = 0.2 - 0.4 mJ Ne gas phase-stabilized electric field Drescher et al., Science 291, 1923 (2001) Hentschel et al., Nature414, 509 (2001) Kienberger et al., Science 297, 1144 (2002)

  9. steering bound electrons with controlled light fields: the generation of a sub-femtosecond pulse 3D-solution of the Schrödinger equation for hydrogen: Armin Scrinzi (TU Vienna)

  10. EL(t) EL(t) EL(t) EL(t) x(t) xuv/x-ray radiation from strongly driven atoms

  11. 1000 Intensity [counts] 0 60 70 80 90 100 110 Photon energy [eV] sub-femtosecond xuv/x-ray pulse generation xuv-filter

  12. 1000 Intensity [counts] 0 60 70 80 90 100 110 Photon energy [eV] attosecond pulse generation and detection time-of-light electron or ion spectrometer xuv and laser pulse act on target particles near- diffraction-limited xuv/soft-x-ray beam atomic gas few-femtosecond, few-cycle laser pulse λL 750 nm Tp= 5 - 7 fs Wp = 0.3 - 0.5 mJ Ne gas Drescher et al., Science 291, 1923 (2001) Hentschel et al., Nature414, 509 (2001) Kienberger et al., Science 297, 1144 (2002)

  13. subsequent core-hole Exuv (t) valence photo- emission +1 final charge state triggering electronic transitions inside atoms by irradiation with xuv-light pulses kin. energy 0 unocc. valence occupied valence core orbital core-level photo- emission +1 Auger decay +2 Auger decay & shake up +2 photo- emission & shake up +1 bind. energy

  14. EL(t) attosecond streak camera Exuv (t) probing electronic transitions inside atoms by means of strong-field-induced free-free transitions: streaking kin. energy 0 unocc. valence occupied valence core orbital valence photo- emission +1 core-level photo- emission +1 Auger decay +2 Auger decay & shake up +2 photo- emission & shake up +1 bind. energy final charge state

  15. electron-optical streak camera resolution ~ 100 femtoseconds D. J. Bradley et al.,Opt. Commun.2, 391 (1971) M. Y. Schelev et al.,Appl. Phys. Lett.18, 354 (1971)

  16. eAL(t) mapping time to momentum momentum change along the EL vector laser electric field Δp(t7) Δp(t6) electron momentum distribution Δp(t5) t1 t2 t3 t4 t5 t6 t7 0 electron release time Δp(t3) time-dependent electron emission Δp(t2) Δp(t1) 0 500 as time -500 as optical-field-driven streak camera J. Itatani et al., Phys. Rev. Lett.88, 173903 (2002) M. Kitzler et al., Phys. Rev. Lett.88, 173904 (2002)

  17. attosecond streak camera: complete measurement of a few-cycle light wave and a sub-fs xuv pulse 6 20 3 [fsMV/cm] 10 light electric field, EL(t) [107 V/cm] 0 0 vector potential, -AL(t) -10 -3 -20 -6 100 measurement In the absence of the laser field simulation 0 60 70 80 90 100 100 60 70 80 90 60 70 80 90 100 final electron energy, Wf [eV] 97 1 single 250-attosecond xuv pulse @ 95 eV 96 95 t instantaneous energy shift [eV] = 250as xuv intensity [arb. u.] 94 93 0 92 -0.2 -0.4 0.0 0.2 -0.4 time [fs] ∆W(t)  eAL(t) 85 electron kinetic energy [eV] 75 65 xuv pulse 0 -4 delay [fs] 4 8 electron counts /bin E. Goulielmakis et al., Science305, (2004)

  18. EL(t) attosecond streaking spectroscopy EXUV (t) probing electronic transitions inside atoms by means of strong-field-induced free-free transitions: streaking kin. energy 0 unocc. valence occupied valence core orbital valence photo- emission +1 core-level photo- emission +1 Auger decay +2 Auger decay & shake up +2 photo- emission & shake up +1 bind. energy final charge state

  19. streaked electron spectra following core-hole excitation in krypton by a sub-fs xuv pulse • tracing core-hole decay directly in time • lifetime of M-shell (3d) vacancy in Krypton: h = 7.91 fs M. Drescher et al., Nature419, 803 (2002)

  20. EL(t) attosecond tunneling spectroscopy EXUV (t) probing electronic transitions inside atoms by means of strong-field-induced bound-free transitions: tunneling kin. energy 0 unocc. valence occupied valence core orbital valence photo- emission +1 core-level photo- emission +1 Auger decay +2 Auger decay & shake up +2 photo- emission & shake up +1 bind. energy final charge state

  21. multiphoton versus tunneling ionization: the Keldysh theory multiphoton ionization: due to absorption of many photons tunneling ionization: due to suppression of Coulomb potential Keldysh parameter: effective Coulomb barrier g > 1 g < 1 tunneling electron emission within a time tmp shorter than the pulse duration electron wave-packets emitted within a time tt shorter than the half-period of the laser Keldysh, L.V., Sov. Phys. JETP 20, 1307 (1965)

  22. high E0 low E0 level 1 level 2 level 1 time evolution of probing – ionization with a few-cycle pulse atomic/ molecular target kin. energy level 1 unocc. valence level 2 occupied valence core orbital bind. energy

  23. attosecond tunneling spectroscopy first experiments in neon and xenon

  24. Ne2+ versus delay time 2.4 % NIR pulse 2.4 % XUV pulse 95.2 % 92.8 % 4.8 % 7.2 % testing the sub-fs resolution with neon A. Kikas et al., J. of Electr. Spectr. and Rel. Phen.77, 241-266 (1996). steps are visible -> sub-fs resolution is valid (signal/noise has to be improved) ..to be published

  25. Xe4+ versus time NIR-DI tA2 = 30.8  1.4 fs tA1 = 6.0  0.7 fs Auger2 Auger1 8.9 % NIR-I NIR pulse tA1 78 % Xe3+ versus time 3.3 % XUV pulse 9.7 % xenon energy levels – illustration of dynamics F. Penent et al., Phys. Rev. Lett. 95, 083002 (2005).

  26. tA2 = 30.8  1.4 fs tA1 = 6.0  0.7 fs resolving electron dynamics in xenon time-integral frequency-resolved experiments: this experiment: tA1 (4d3/2) = 6.3  0.2 fs tA1 (4d5/2) = 5.9  0.2 fs tA2 > 23 fs F. Penent, Phys. Rev. Lett. 95, 083002 (2005). ..to be published

  27. coworkers & collaborators postdoctoral: A. Apolonski A. Baltuska A. Cavalieri T. Fuji E. Goulielmakis R. Kienberger J. Seres M. Uiberacker V. Yakovlev PhD candidates: N. Ishii T. Metzger J. Rauschenberger M. Schultze C. Theisset A. Verhoef graphics: Barbara Ferus xuv optics & atomic spectroscopy: Th. Uphues,U. Kleineberg, U. Heinzmann Univ. Bielefeld, Germany M. Drescher Univ. Hamburg, DESY, Germany light phase control: Ch. Gole,R. Holzwarth, T. Udem, T. W. Hänsch Univ. Munich - MPQ Garching, Germany & measurement: G. Paulus, H. Walther A&M Univ. Texas, USA / MPQ Garching Ch. Lemell, J. Burgdörfer, A. Scrinzi Vienna Univ. Techn., Austria metrology: P. B. Corkum, M. Yu. Ivanov NRC Canada, Ottawa, Canada molecular spectroscopy: M. Kling, M. Vrakking AMOLF, Amsterdam, Netherlands M. Lezius, K. Kompa MPQ Garching, Germany

  28. End

  29. D+ right + D D D+ left + D D may attosecond control of electronic motion in chemical bonds affect the outcome of molecular dynamics? 2pσu+ D2+ 1sσg+ 1 ionization of D2 2 recollisional excitation 3 formation of a coherent superposition (1ssg+,2psu+) state in D2+ 2 3 D2 phase-controlled few-cycle wave 1 e- R EL(t) 0.5 asymmetry left/right 0 -0.5 15 time[fs] 5 10 0 -5 YES: direction of emission of D+ is controlled by light waveform M. Kling et al., Science 312, 246 (2006)

  30. time left right M. Kling et al., Science 312, 246 (2006)

  31. time left right M. Kling et al., Science 312, 246 (2006)

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