Ultrafast nanoscience with ELI ALPS

Transcription

1 Ultrafast nanoscience with ELI ALPS Péter Dombi Wigner Research Centre for Physics, Budapest & Max Planck Institute of Quantum Optics, Garching Overview ultrafast (femtosecond/attosecond) dynamicsin metal nanosystems functional molecules potential of ELI ALPS in high time resolution and broad spectral coverage (+higher photon flux than university scale labs) + some metrology options 1

2 Some applications of light nanoparticle interaction Increasing solar cell efficiency ( thin film solar cells etc.) XUV pulses high harmonic generation with high repetition rate Kim, Nature Phot. 5, 677 (2011) 75 MHz 10 fs IR laser pulses cancer therapy with nanoparticles etc. etc. Characteristic time scales in solids 1 Energy bandwidth / ev Screening Dephasing e e scattering e phonon scattering Time scale / fs Adapted from Petek, Ogawa, Progr. Surf Sci Easily achievable laser pulse duration Optical period at 800nm Electron emission duration 2

3 Fundamental (ultrafast) questions in plasmonics how do collective electron oscillations build up on femto/attosecond time scales? how is dynamics related to nanoparticle functionality? how can the interaction be controlled on the same scales? developing applications in photovoltaics, life science, HHG/THz sources etc. Tools: combining existing attosecond and surface/materials science tools One option: looking at plasmonic photoelectrons tools: looking at plasmonic photoelectrons emitted from nanoparticle +strong laser fields 3

4 Coupling of localized plasmons Example: electric field amplitudes on a nanorod with resonant excitation Field enhancement factor 80 nm 150 nm Incident laser wavelength: 800 nm Incident light polarization along longest axis of nanorod Nanorod thickness: 40 nm Fiel enhancement ~ x50 (!) 4

5 Investigating strong field phenomena at nanoparticles Advantages: electricfield controllable on the nanoscale by particle geometry ultrahigh plasmonic field enhancement (x100s feasible!) strong field phenomena with extremely low laser intensities (oscillators) Ultrafast photoemission from nanoparticles I control in space Time of flight spectrometer for electrons 80 fs / 165 nj / 4.5 khz illumination (Ti:S laser in Budapest) Dombi et al., Nano Lett. 13, 674 (2013). 5

6 Ultrafast photoemission from nanoparticles I control in space Control of electrons with nanolocalized plasmon field Dombi et al., Nano Lett. 13, 674 (2013). Ultrafast photoemission from nanoparticles II control with pulse Carrier-envelope phase El ectric field strength (a.u.) \c(a(t)) 0 =0 0 = /2 0 = \c(e(t))=\c(a(t))cos( t+\c( \c(a(t))cos( t+\c( 0 )) /f r Time (fs) 2/f r 0 =3 /2 3/f r 6

7 Ultrafast photoemission from nanoparticles II control with pulse Courtesy of Péter Földi, University of Szeged CEP Attosecond nanoscience tools with ELI ALPS - attosecond streaking measurments on nanoparticles for ultrafast dynamics PEEM, VMI etc. for time and space resolved information on these systems PEEM M. Stockman et al., Nature Phot

8 Another application of plasmonic nanoparticles: THz generation in: 100 fs 800 nm pulses 5 20 GW/cm 2 out: THz pulses 0.6 THz Signal 10% of signal with optical rect. in ZnTe Nanostructured sample with nanosphere lithography Correlation between plasmonic resonance of nanoparticles and THz signal Polyushkin et al., Nano Lett. 11, 4718 (2011). What is the THz generation mechanism? Optical rectification on nanofilm or radiation by photoemitted electrons in local inhomogeneous field??? both THz and electron signals tested on same samples D. Polyushkin, P. Rácz et al., submitted 8

9 Functional molecules 0 1 Spin-state switching - high potential in IT - small molecules, rapid switching S = aim: explore switching mechanism, design better molecules Light-harvesting model systems A. Fihri et al., Angew. Chem. Int. 2008, 47, 564 Functional molecules Spin-state switching: theory 0 1 S = 0 2 C. Sousa et al., Chem. Eur. J., 2013 DOI: /chem Few-cycle probes necessary 9

10 Pump probe studies to look at ultrafast processes laser pulse t=0 t=infinity IR, VIS X-ray spectroscopy (absorption, emission, inelastic scattering) diffuse scattering X-ray diffraction reaction coordinate Here ELI ALPS can be complementary to X ray facilities (LCLS, XFEL) with additional pump probe options and better time resolution New fs sources: free electron hard X ray lasers Linear Coherent Light Source, SLAC, Stanford, USA Expected for 2016 Available since 2010 European XFEL, Hamburg (DESY) Available since 2012 SACLA, Hyogo, Japán Here ELI ALPS can be complementary to X ray facilities with some additional optical pump probe options 10

11 ELI ALPS metrology and instrumentation options ELI-ALPS SYLOS 1 laser vs. HELIOS laser operating in Budapest: 1 khz, 20 mj, fs vs. 1 khz, 4 mj, 31 fs proof-of-principle HHG etc. experiments testbed systems for ELI femtosecond testing of optical components + additional options - large-aperture fs mirror production - optics testing ti (wavefront, scatter etc.) - vibration analysis of building, sub-systems etc. - many ELI-relevant training options (fs lasers, HHG, electron spectroscopy etc.) Outlook full control of electrons with laser fields on the nanoscale understanding ultrafast collective electron dynamics understanding transitions in functional molecules tailoring them for applications ELI ALPS tools are ideal for this short pulses together with state of the art diagnostics +uniquely broad wavelength coverage 11

12 Acknowledgements Péter RÁCZ, István MÁRTON, Júlia FEKETE G. FARKAS, A. CZITROVSZKY, N. KROÓ, I. FÖLDES, G. VANKÓ Wigner Research Centre for Physics, Budapest groups Joachim KRENN, Ulrich HOHENESTER groups University of Graz, Austria Péter FÖLDI, Mihály BENEDICT University of Szeged WilliamBARNES & group University of Exeter, UK Jens BIEGERT & group ICFO, Barcelona 12