John T. Costello National Centre for Plasma Science & Technology (NCPST)/ School of Physical Sciences, Dublin City University Photoionization in Intense XUV and NIR Laser Fields with the FLASH Pump-Probe Facility EU COST MP0601 Meeting, Dresden, Nov 28 (2008) ' FLASH ' - Free Electron LASer in Hamburg

LIXAM (Orsay, France) D. Cubaynes, D Glijer, P. O’Keeffe, M. Meyer DESY (Hamburg, Germany) S. Düsterer, A. Azima, P. Radcliffe, H. Redlin, W-B Li, J. Feldhaus Dublin City University (Ireland) J. Dardis, P. Hayden, P. Hough, K. D. Kavanagh, H. de Luna, J. Pedregosa-Gutierrez, V. Richardson, P. Yeates, E. T. Kennedy & J. T. Costello Queens University Belfast (N. Ireland, UK)University of Padua (Italy) A. Delserieys, Ph. Orr, D. Riley, C. L. S. LewisL. Poletto and P Nicolosi Thanks also to AG Photon (R Treusch et al.) & AG Machine (M Yurkov et al.) Two-Colour ‘FLASH’ Collaboration EU COST MP0601 Meeting, Dresden, Nov 28 (2008)

Collaboration grew out of EU RTD Project: HRPI-CT Title:“X-Ray FEL Pump Probe Facility” Partners: Orsay, DCU, Lund, MBI, BESSY & DESY Collaboration - Origin EU COST MP0601 Meeting, Dresden, Nov 28 (2008)

FLASH Overview Coherent Atomic Photoionization Processes Intense XUV + NIR Fields Next steps - Two Colour Resonant Processes Outline of the Talk EU COST MP0601 Meeting, Dresden, Nov 28 (2008)

300 m FLASH Overview LINAC Energy: 0.3 – 1 GeV     6.5 – 60 nm Laser Bunch Compressor Bypass Undulators Collimator Bunch Compressor 5 MeV127 MeV450 MeV1000 MeV Accelerating StructuresDiagnostics FEL Diagnostics RF-gun EU COST MP0601 Meeting, Dresden, Nov 28 (2008)

water window Wavelength range (fundamental): nm FEL harmonics nm): 3 rd : 4.6 nm (270 eV) 5 rd : 2.7 nm (450 eV) Spectral width (FWHM): % Pulse energy: 50 µJ (average), 170 µJ (peak) Pulse duration (FWHM): fs Peak power (fundamental): Few GW Average power (fundamental): 0.1 W (up to 3000 pulses / sec) Photons per pulse: ~ FLASH: Key Performance Indicators W. Ackermann et al., Nature Photonics (2007)

O/P Profile and Spectral Distribution Spectral FluctuationsTemporal Fluctuations EU COST MP0601 Meeting, Dresden, Nov 28 (2008) SASE – ‘Self Amplified Spontaneous Emission’ => FEL output builds up from spontaneous emission (photon noise) => Fluctuations in beam profile, pointing stability, intensity, spectral distribution and pulse duration !!

Part 2 - Atomic Physics Experiments with FLASH EU COST MP0601 Meeting, Dresden, Nov 28 (2008)

Part 2. Atoms in Intense (Non- Resonant) XUV + NIR fields Photoionization of rare gas atoms dressed by intense optical fields Summary of Photoionization Experiments with the Ultrafast EUV Laser FLASH - Free Electron Laser in Hamburg J T Costello, J Phys Conf Ser 88 Art No (2007) EU COST MP0601 Meeting, Dresden, Nov 28 (2008)

FLASH Optical and EUV Beam Layout PG2 BL1 BL3 BL2 visible laser light EU COST MP0601 Meeting, Dresden, Nov 28 (2008)

E.S. Toma et al. PRA (2000) Two Colour ATI Electron Spectrometer gas jet Visible fs laser pulse VUV A. Superposition of visible and VUV pulses in a rare gas jet ‘Non-invasive’ Ar(IP) eV h  ir =1.55eV Sideband intensity very sensitive to pulse overlap Q. How do we measure fs XUV-NIR time delays ?

P. Radcliffe, et al., Nucl. Instr. and Meth. A 83, (2007) Two Colour ATI Experimental Layout at FLASH - (EU-RTD)

Two Colour ATI P. Radcliffe, et al., Nucl. Instr. and Meth. A 83, (2007) P Radcliffe, et al., APL (2007) Sideband number/intensity depend strongly on EUV/NIR overlap  by comparison with theory we should be able to determine relative time delay to better than 50 fs Single Shot TC-ATI in Xe:  t ~ 50 fs

FLASH: 13.7 nm, fs, 20µJ OL: 800nm, 4ps, 400µJ, 6 x W/cm 2  (  ) = 3S d + (5S s + S d ) cos 2  FLASH: 13.7 nm, fs, 20µJ OL: 800nm, 4ps, 400µJ, 8 x W/cm 2 He 1s 2 + h XUV ----> He + 1s +  p He 1s 2 + h XUV + h OL ---> He + 1s +  s,  d  Atomic Dichroism in Two colour ATI Strong Polarisation Dependence of Sidebands (Low Field)

Atomic Dichroism in Two colour ATI - He He 1s 2 + h XUV + h NIR  He + 1s +  s,  d Low Optical Laser FieldHigh Optical Laser Field Theory: A Grum-Grzhimailo SPA Theory: A Maquet/ R Taieb M Meyer, J Dardis et al. PRL 101 Art. no (2008)

Challenges/Questions 1.Is theory beyond Soft Photon Approximation needed for sideband scaling and dichroism? 2.If so, must it account for all angular momentum couplings/ electron correlations to high order ? 3.Not easy for He and would be perhaps quite (very) difficult for Xe 4.He, SB1 (  s,  d). SPA and ab-initio calculations with full angular momentum coupling give the same final results. For Xe, SPA in agreement with experiment. Ne, Kr under analysis. EU COST MP0601 Meeting, Dresden, Nov 28 (2008)

Part 3. Current and Future Interests Two Colour Resonant Photoionization Processes 1.To date we have looked only at one and two colour non-resonant processes 2. Next phase - FEL tunable and so we can explore resonant two colour processes where inner shell electrons dominate EU COST MP0601 Meeting, Dresden, Nov 28 (2008)

‘Double Optical’ AIS Resonance EU COST MP0601 Meeting, Dresden, Nov 28 (2008) E G.S. Laser-prepared state excited Core-excited FLASH OL FLASH E G.S. Two-color resonances Coupling of AIS Core-excited FLASH E G.S. Ionic state coupling Core-excited ionic Auger Initial State Coupling

Bachau & Lambropoulos, PRA (1986) Themelis, Lambropoulos, Meyer, JPB (2005) ‘New Knobs’ 1.Laser Frequency 2.Laser Intensity Tunable Optical Laser - Laser Coupling of autoionization states - 'Autler Townes' Autoionizing Resonances - He EU COST MP0601 Meeting, Dresden, Nov 28 (2008) R P Madden and K Codling PRL (1963) He + h (60.2 eV)  He (2snp 1 P)  He + 1s +  p He (2s2p 1 P)

Bachau & Lambropoulos, PRA (1986) Themelis, Lambropoulos, Meyer, JPB (2005) ‘New Knobs’ 1.Laser Frequency 2.Laser Intensity Tunable Optical Laser - Laser Coupling of autoionization states - 'Autler Townes' Autoionizing Resonances - He EU COST MP0601 Meeting, Dresden, Nov 28 (2008)

EIT with AIS - XUV Gate ? Quantum Optics with Unbound States Demonstration of EUV transparency switching, Loh, Greene & Leone Chem. Phys (2008) EU COST MP0601 Meeting, Dresden, Nov 28 (2008)

Next Steps for AMOP at FLASH - Technical Developments EUV stabilisation Seeding option ( ) Seeding with HHs - ‘Full’ coherence 2W & 3W of 800 nm - Two colour AIS excitation (2009) OPA Tunable - <0.3 mJ,  m (2010) Synchronisation - New FIR Undulator EU COST MP0601 Meeting, Dresden, Nov 28 (2008)

In Conclusion 1.To date we have looked only at one and two colour non- resonant photoionization processes 2.Next phase - OL & FEL tunable. We can explore resonant two colour processes where inner shell electrons dominate 3.Ultrafast EUV and X-ray switching possible with EIT via AIS: Expts at DCU (2009). M Kelly  Brockelsby/Vrakking 4.Study fragmentation and ionization from vibrationally excited/selected wavepackets in simple molecules 5.Beyond 2009: Seeding, fs jitter and attosecond pulses: Photoionization - Dissociation Imaging Dynamics LCLS (US X-ray FEL User Facility)/ 2015 XFEL (European User Facility) EU COST MP0601 Meeting, Dresden, Nov 28 (2008)