Introduction to FERMI TIMER end-station Transient Grating experiments Multi-Color experiments

Transcription

1 Introduction to FERMI TIMER end-station Transient Grating experiments Multi-Color experiments FERMI based Multi- Wave Experiments C. Masciovecchio Elettra-Sincrotrone Trieste, Trieste I-34149

2 Why Free Electron Lasers? Synchrotron radiation 10keV 1 A HPE FELs Plasma lasers 1keV 1 nm HHG in gases 100eV 10nm LPE FELs 10eV 100 nm Conventional lasers 1eV 1ns 100ps 10ps 1ps 100fs 10fs 1fs 1μm Pulse Duration Imaging with high Spatial Resolution (~ λ): fixed target imaging, particle injection imaging,.. Dynamics: four wave mixing (nanoscale), warm dense matter, extreme condition,... Resonant Experiments: XANES (tunability), XMCD (polarization), chemical mapping,

3 SASE vs Seeded x 10 5 L. H. Yu et al., PRL (2003)

4 E. Allaria et al., Nat. Phot. (2012) t < 100 fs Flux ~ ph/pulse λ ~ (1) nm Total Control on Pulse Energy Photons/pulse Time Shape Polarization Wavelength (nm)

5 The Experimental Hall EIS (Elastic & Inelastic Scattering) C. Masciovecchio et al., J. Synch. Rad. (2015) Commissioning F. Bencivenga et al., J. Synch. Rad. (2015) TIMER TIMEX LDM (Low Density Matter) C. Svetina et al., J. Synch. Rad. (2015) MagneDYN (Magnetic Dynamics) TeraFERMI (THz beramline) DIPROI (DIffraction & PROjection Imaging) F. Capotondi et al., J. Synch. Rad. (2015)

6 The Experimental Hall TIMEX DIPROI LDM TIMER

7 TIMER TIMER TIME-Resolved spectroscopy of mesoscopic dynamics in condensed matter Challenge: Study Collective Excitations in Disordered Systems in the Unexplored ω-q region Determination of the Dynamic Structure Factor: S(Q,ω) Q (θ) θ 10 2 BLS IUVS IXS BL30/21 ω = c s Q ω (mev) BL10.2 INS macro-scale nano-scale atomic-scale Q ( nm -1 )

8 Why Disordered Systems? Unsolved problems in physics Condensed matter physics Amorphous solids What is the nature of the transition between a fluid or regular solid and a glassy phase? What are the physical processes giving rise to the general properties of glasses? High-temperature superconductors What is the responsible mechanism that causes certain materials to exhibit superconductivity at temperatures much higher than around 50 Kelvin? Sonoluminescence What causes the emission of short bursts of light from imploding bubbles in a liquid when excited by sound? Turbulence Is it possible to make a theoretical model to describe the statistics of a turbulent flow (in particular, its internal structures)? Also, under what conditions do smooth solution to the Navier-Stokes equations exist? Glass is a very general state of condensed matter a large variety of systems can be transformed from liquid to glass The liquid-glass transition cannot be described in the framework of classical phase transitions since T g depends on the quenching rate one cannot define an order parameter showing a critical behaviour at T g

9 Why at the nanoscale? The nature of the vibrational dynamics in glasses at the nanoscale is still unclear (V-SiO 2 ) P. Benassi et al., PRL 77, 3835 (1996) Existence of propagating excitations at high frequency M. Foret et al., PRL 77, 3831 (1996) They are localized above ~ 1 nm -1 F. Sette et al., Science 280, 1550 (1998) They are acoustic-like G. Ruocco et al., PRL 83, 5583 (1999) Change of sound attenuation mechanism at nm -1 B. Ruffle et al., PRL 90, (2003) Change is at 1 nm -1 C. Masciovecchio et al., PRL 97, (2006) Change is at 0.2 nm -1 W. Schirmacher et al., PRL 98, (2007) Model agrees with Masciovecchio et al. B. Ruffle et al., PRL 100, (2008) Shirmacher model is not correct G. Baldi et al., PRL 104, (2010) Change is at 1 nm -1 PRL 112, (2014); Nat. Comm. 5, 3939 (2014); PRL 112, (2014) Fundamental to understand the low temperature anomalies in glasses

10 TIMER ω (mev) 10 2 BLS IUVS IXS INS Solution: Free Electron Laser based Transient Grating Spectroscopy E pump Q(λ,θ) θ E signal F(Q,t) Q ( nm -1 ) E probe E pump S(Q,ω) (a.u.) ω (mev) H 2 O 2 nm -1 F(Q,t) (a.u.) Gaussian-like time profile t (ps)

11 Typical Infrared/Visible Set- Up M Delay Line λ 1 Probe laser beam DM λ 2 =2λ 1 Excitation laser beam Phase Control (Heterodyne) Beam stop (Homodyne) Neutral Filter (Heterodyne) E ex1 E L APD M DOE: Phase Mask E pr Sample AL1 E ex2 AL2 E s (Homodyne) E L +E s (Heterodyne) Challenge: Extend and modify the set-up for UV Transient Grating Experiments

12 TIMER Layout Delay line: 4 ML mirrors (abs 1 st, reflect 3 rd harm), time delays up to ~ 3 ns 3 rd harmonic (probe) 2θ θ B Beam waist Original beam Vertical Pump1 Pump2 FEL pulse:1 st and 3 rd harmonic (λ 3 = λ 1 /3) Focusing mirror Plane Mirrors beam splitters 1 st harmonic (pump) Horizontal sample position Vertical Horizontal

13 DIPROI Si 3 N 4 reference sample θ B FEL 1 Detector (EUV-Vis cross-corr.) FEL 2 λ opt M 1 M 2 M 0 λ FEL = 27.6 nm Beamstops R / R 0,00-0,02-0,04 - FEL 1 - FEL 2-0, t (ps) M 1 M 0 F. Bencivenga et al., NIMA (2010) R. Cucini et al., NIMA (2011) R. Cucini et al., Opt. Lett. (2011) F. Casolari et al., Appl. Phys. (2014) M. Danailov et al. Opt. Express (2014) R. Cucini et al., Opt. Lett. (2014) 2θ M 2 ± 0.5 ps at 2θ = constant

14 FEL Transient Grating Experiments on V- SiO 2 V-SiO 2 sample FEL 1 M 1 M 0 λ FEL = 27.6 nm Inprints on SiO 2 2θ = o FEL 2 M 2 Grating visibility after multi-shot explosure FEL 1 -FEL 2 optical path difference < λ FEL Permanent gratings on SiO 2 (after 1000 s FEL flux > 50 mj/cm 2 ) Clean sample X (nm) μm -10 µm µm X (nm)

15 FEL Transient Grating Experiments on V- SiO 2 F. Bencivenga et al., Nature 2015 θ k FEL,1 M 1 M 0 2θ 2θ λ FEL = 27.6 nm θ B k FEL,2 M 2 CCD λ opt

16 Transient Grating Experiments on V- SiO 2 Hyper - Raman modes due to coupled tetrahedral rotations ν THz Raman modes due to tetrahedral bending ν THz Acoustic-like excitations

17 Four Wave Mixing at FEL s ω 1 k 1 ω 4 k 4 Transient grating is one of Four Wave Mixing techniques Coherent Antistokes Raman Scattering (CARS) P. D. Maker et al., Phys. Rev. (1965) ω 3 k 3 ω 2 k 2 CB Charge transfer dynamics in metal complexes Charge injection in metal oxides nanoparticles Quasiparticle diffusion (Polarons) VB ω 2 ω 1 Δt ω 3 ω out atom-a S. Tanaka et al., PRL (2002) atom-b Measure the coherence between the two different sites it makes possible to chose where a given excitation is created, as well as where and when it is probed delocalization of electronic states and charge/energy transfer processes

18 Multiple pulse configurations Multiple pulses can be generated by double pulse seeding gain bandwidth time Spectral separation % (E. Allaria et al., Nat. Comm 2013) spectrum RAD2 gain bandwidth Spectral separation 2-3% MOD gain bandwidth time spectrum RAD1 gain bandwidth spectrum or much larger if two radiators are tuned at different harmonics (Sacchi et al., Nat. Comm. 2016) MOD gain bandwidth time spectrum Two (almost) temporally superimposed pulses at harmonic wavelengths of the seed. They are correlated in phase that can be controlled with the phase shifter (K.C. Prince et al., Nat. Phot. acc.)

19 Multicolor at FERMI E. Allaria et al.,(2013) λ 2 λ 1pump

20 Element selective magnetization dynamics E. Ferrari et al., (2016) Radiators at different harmonics T Ni 0.81 Fe 0.19 NiFe 2 O 4

21 FERMI based CARS T T THG λλ seed nm OPA λλ seed variable λλ 2 λλ 1 - λλ λλ nm 2 colored FEL Pulses

22 FERMI based CARS 1 Si 3 N 4 CARS 110 mev Si 3 N 4 CARS 255 mev Signal without normalization F. Bencivenga et al., in preparation Time ps

23 TIMER commissioning 3 rd harmonic (probe) FEL pulse:1 st and 3 rd 1 st harmonic (pump) 1) The experimental chamber was tested and equipped with most of the final devices (invacuum piezo tip-tilt stages, in-vacuum CCD, photodiodes, telemicroscope, etc.). 2) The mechanics of the photon transport system (except two chambers for wide angle TG) and the EUV mirrors for splitting and focusing of the pumping pulses have been installed. 3) The optical transport system and the breadboard for the pobing laser have been installed. 4) Most of the infrastructure for controls and data acquisition has been installed.

24 TIMER commissioning Detector (EUVvis cross-corr.) sample 1,05 1, , ,00 0,95 0,95 2θ θ B Reflectivity drop (%) ΔR/R 0,90 0,85 0,80 Reflectivity drop (%) 0,90 0,85 0,80 0, Reflectivity drop (%) ΔR/R 0,75 0, Time (ps) 1, ,00 0,95 0,90 0,85 0,80 0,75 0,70 0, , Δt ~ 1.7 ps Time (ps) FEL-optical delay (ps) Reflectivity drop (%) 0.7 0,70 0,65 1, ,00 0,95 0,90 0,85 0,80 0, ,70 0, Time (ps) Δt ~ 0 ps Time (ps) FEL-optical delay (ps) F. Bencivenga et al., in preparation

25 Acknowledgments F. Bencivenga L. Giannessi M. Danailov M. Zangrando M. Svandrlik M. Manfredda F. Capotondi A. Gessini A. Simoncig M. Kiskinova E. Pedersoli E. Principi R. Mincigrucci R. Cucini K. Nelson G. Knopp G. Monaco