Atomic Physics with VUV-FEL Radiation R. Moshammer MPIK-Heidelberg SASE FEL Radiation (Self Amplification of Spontaneous Emission Free Electron Laser) Unique Light Sources VUV-FEL User Facilities I. Multi-Photon Processes in Atoms & Molecules Interactions with Molecular Ions Spectroscopy & Ionisation of Ions II.

bunch of N e electrons Undulator Synchrotron-Radiation From Synchrotron Radiation to FEL-Light Power  N e

bunch of N e electrons Undulator Synchrotron-Radiation From Synchrotron Radiation to FEL-Light Power  N e

From Synchrotron Radiation to FEL-Light Undulator Self Amplified Spontaneous Emission (SASE) bunch of N e electrons Power  N e 2 FEL-Radiation

measured Sept From Synchrotron Radiation to FEL-Light Gain in Quality & Power: 5-8 Orders 5-8 Orders of Magnitudes

High-Power Laser versus FEL proposed FEL’s

Full coherence:  /  Photon energies: eV to 10 keV Pulse width :  T < 100 fs Rep. Rate : up to 70 kHz Photons / Pulse : Peak-Power : MW to GW Intensities: I > W/cm 2 Non-Linear Processes in Atoms (Molecules) Atomic Reactions with Small Cross-Sections Unique Light Sources

Proposed Facilities BESSY: E  < 1 keV SLAC : E  < 8 keV TESLA : E  < 14 keV Daresbury, Spring8, Under construction TESLA Test Facility (TTF at DESY Hamburg) Start of user experiments in 2004 E  < 200 eV VUV-FEL User Facilities

Hamburg: TESLA Test Facility (TTF)

Multi-Photon Processes in Atoms & Molecules Interactions with Molecular Ions Spectroscopy & Ionisation of Ions Atomic Physics (Approved TTF - Experiments) Universität Frankfurt:R. Dörner, L. Schmidt, Th. Weber Fritz-Haber Institut Berlin:U. Becker Universität Hamburg:B. Sonntag Max-Planck-Institut Heidelberg:R. Moshammer, A. Dorn, D. Fischer, C.D. Schröter, J. Ullrich Max-Planck-Institut Heidelberg: H.B. Pederson, A. Wolf, D. Schwalm, J. Ullrich Weizmann Institute Rehovot:D. Zajfmann Max-Planck-Institut Heidelberg: J.R. Crespo, J. Braun, J. Bruhns, A. Dorn, R. Moshammer, C.D. Schröter, J. Ullrich Fudan University Shanghai Y. Zou LLNL Livermore P. Beiersdorfer

Multi-Photon Processes in Atoms & Molecules Interactions with Molecular Ions Spectroscopy & Ionisation of Ions Atomic Physics

Multi-Photon Processes in Atoms Multi-Photon Processes in Atoms & Molecules Interactions with Molecular Ions Spectroscopy & Ionisation of Ions

Experimental Approach Supersonic gas jet Atoms, Molecules FEL Spectrometer: Ion-electron coincidence  eV ion energy resolution meV electron resolution Drift Detector position-sensitive, multi-hit Helmholtz coils Reaction-Microscope El. field

Ultra high vacuum : p < mbar Ultra cold gas-jet : T < 1 Kelvin Multi-hit detectors :  = 12 cm,  t ~ 10 ns Laser beam Ion-detector Gas-jet Electron-detector Experimental Approach

From Single Photons to Many Photons Ionisation of Atoms High Intensity Lasers I = W/cm 2 h << I p Many Photons Single Photon h > I p Synchrotron-Radiation Few PhotonsFEL

Single Photon From Single Photons to Many Photons Tunneling  W/cm 2 Electron-Energy E e   Many PhotonsFew Photons ? Dörner (1997)

Dörner et al. (2001) From Single to Double Ionization Single Photon P || /a.u Many Photons 

Single PhotonMany Photons  e2e2 e1e1 e2e2 e1e1 ! well understood ! ! many open questions ! From Single to Double Ionization

e - momentum P || (e 1 ) [a.u.] P || (e 2 ) [a.u.] Experiment too many photons classical field  ponderomotive motion Theory (Goreslavski et al.) Exp.: MBI-Berlin, MPI-Heidelberg, Frankfurt, Marburg Theory: Becker, Faisal, Taylor, Goreslavski..... Problems:

“Few” Photons: FEL - Radiation Helium ponderomotive potential U p  I/  2  0 tt possible Mechanisms: e.g. E   = 50 eV

energy [eV] Helium electron energy tt

Multi-Photon Double Ionization Numerical Solution of the Schrödinger-Equation Parker & Taylor J. Phys. B34 (2001) h = 87 eV I = W/cm 2 momentum electron 1 [a.u.] momentum electron 2 [a.u.] Perturbation theory Colgan & Pindzola PRL 88 (2002) Two-Photon Absorption at h = 45 eV 1 h 2 h 3 h Absorption above threshold

Multi-photon single ionisation Two-photon innershell ionisation More Processes R. Hasbani, E. Cormier and H. Bachau J. Phys. B 33 (2000) 2101 S.A. Novikov and A.N. Hopersky J. Phys. B 33 (2000) 2287

Molecules Multi-Photon Processes in Atoms & Molecules Interactions with Molecular Ions Spectroscopy & Ionisation of Ions Atomic Physics

Molecules: Fixed-in-Space Shigemasa et al. PRL 74 (1995) Heiser & Becker et al. PRL 79 (1997) Landers & Dörner PRL 87 (2001) “Molecules illuminated from within” C O 10 eV Auger  

pump h 1 h 2 probe Fixed-in-Space & Pump-Probe photo-electron angular distribution fs time-scale for dissociation “Snapshots” of the time-evolution of intra-molecular potentials “Movie” of the dissociation reaction U. Becker, R. Dörner

Atomic Physics Multi-Photon Processes in Atoms & Molecules Interactions with Molecular Ions Spectroscopy & Ionisation of Ions

VUV Photodissociation of Molecular Ions A. Wolf, D. Zajfman, D. Schwalm Energy R DirectPredissociation Spontaneous radiative diss.

Hollow cathode ion source 5 kV electrostatic ion beam trap Einzel lens Kinetic energy release Angular distributions Cross sections Cold molecular ions Relaxation time (CH + ) ~ 0.4 sec VUV FEL Extracted ion bunch extraction time ~ 50 ns ~ 10 pulses per fill of trap Experimental Approach Photodissociation Imaging A. Wolf, D. Zajfman, D. Schwalm Molecular ions e.g. CH + Photon induced Dissociation

from Hartquist, Williams Cambridge Univ. Pr H2H2 H2+H2+ CH + H3+H3+ CO HCO + e-e- C h e-e- H2H2 Interstellar cloud chemistry Example: CH + (production of oxygen-bearing molecules) CO

from Hartquist, Williams Cambridge Univ. Pr H2H2 H2+H2+ CH + H3+H3+ CO HCO + e-e- C h e-e- H2H2 Interstellar cloud chemistry Example: CH + (production of oxygen-bearing molecules) loss mechanism photodissociation CO Ex: Diffuse Cloud ( ξ Ophiuchi): N Obser (CH + ) = 2.9·10 13 cm -2 N Model (CH + ) = 2.8·10 10 cm -2

estimated CH n + H2O+H2O+ H3O+H3O+ NH n + Relevant Photon Energies: Interstellar clouds: < 13.6 eV Close to stars: < 50 eV

estimated CH n + H2O+H2O+ H3O+H3O+ NH n + Relevant Photon Energies: Interstellar clouds: < 13.6 eV Close to stars: < 50 eV FEL -Radiation !!

Multi-Photon Processes in Atoms & Molecules Interactions with Molecular Ions Spectroscopy & Ionisation of Ions Atomic Physics (Approved TTF - Experiments)

1 m FEL-apparatus: (under construction) FEL beam    Experimental Approach J. Crespo, P. Baiersdorfer, J. Ullrich

Precision Spectroscopy on Ions I. Test of 1e - QED at Z  ~ 1 II. Few-Electron QED III. Determination of Nuclear Properties Magnetisation Distribution Magnetic Moment distribution Charge Radius Neutron Distribution IV. Electroweak Radiative Corrections V. Life Time Measurements FEL-Light:  /  

Lamb-shift in Li-like Ions QED contribution FEL bandwidth:  /  Expected accuracy:   BEVALAC (U 89+ )  0.10 eV no data typical exp. accuracy:  E  E =

urgently needed (opacity project) Photoionization of Ions very few data (luminosity) differential data (merged beams) M. A. Bautista J. Phys. B 33 (2000) L419 Photo ionization near threshold: Fe XV [2p 6 3s 2 ( 1 S)] R-matrix OP cross sections Multi-Photon Ionization! Above Threshold Ionization! Few photon – Few electrons! High Harmonic Generation Differential Data

Extracted Beams from the EBIT combine FEL-radiation Future: Exciting LEIF with FEL‘s