Photoinitiated dynamics studied in the femto- to nanosecond time and the
terahertz to petahertz frequency domain: PIDID a multi-institutional initiative
The PIDID project will substantially improve the experimental opportunities for accelerator based time-resolved measurements in Germany. The proposed development of the experimental infra-structures at FELBE and FLASH will establish a complementary instrumentation that allows the contributing groups for the first time to perform their research in an unprecedented combination of fs – ns time- and THz – PHz frequency domain. The close collaboration of German and Russian partners will carry out the development which will master solutions to the problems that presently inhibit a routine user program at the two facilities.
At the heart of this proposal is the fundamental finding that understanding of the fs – ns dynamics of photoinitiated and phonoinitiated dynamics in materials requires a combination of techniques and light pulse properties only available from accelerator based photon sources, while at the same time the available instrumentation at the two German 4th generation photon facilities FLASH and FELBE is in its present state not yet prepared to adequately fulfill the needs of the growing user communities.
- 02/2011, postdoc at FUB/HZDR starts work (WP3)
- 09/2011 postdoc at DESY starts work (WP4)
- 12/2011 first (pilot) users from U Niemegen, FHI and HZDR at the ps - kHz pump probe beamline at FELBE
- 16.12.2011 - Kick Off workshop @ DESY/talks: FLASH overview, FELBE/TELBE overview, Status WP2, Status WP3, Status WP4, Status WP5
- 01/2012 laser tables for new THz photondiagnostic station at FLASH installed
- 16.03./17.03.2012 FTIR measurements at THz beamline @ FLASH
- 11/2012: beamtime for investigation of photosensitive protein dynamics and water under selective vibrational excitation at the THz FEL FELBE
- 11/2012: THz pump X-ray probe beamtime @ FLASH with DESY and the MPI Heidelberg
- 10.02.2012 - 17.12.2012: THz pump X-ray probe / Magnetization dynamics experiment @ FLASH (collaboration with university of Niemwegen, HZB, DESY and FHI)
- F. Tavella, N. Stojanovic, G. Geloni & M. Gensch, Few Femtosecond Timing at Fourth Generation X-ray Lightsources, Nat. Photon. 5 (2011), 162
- M. Foerst, M. Gensch, R. Riedel, F. Tavella, E.A. Schneidmiller, N. Stojanovic, M.V. Yurkov, Optical afterburner for a SASE FEL: First results from FLASH, Proceedings of IPAC2011, San Sebastian (2011).
- C. Bauer, M. Gensch, J. Heberle, Enroute to investigating protein dynamics under vibrational excitation at the THz FEL FELBE, Journal of Physics: Conference Series, 359, 012011 (2012)
- C. Kaya, C. Schneider, A. Al-Shemmary, W. Seidel, M. Kuntzsch, J. Bhattacharyya, M. Mittendorff, P. Evtushenko, S. Winnerl, G. Staats, M. Helm, N. Stojanovic, P. Michel, and M. Gensch, Phase sensitive monitoring of electron bunch form and arrival time in superconducting linear accelerators, Appl. Phys. Lett. 100, 141103 (2012).
- R. Jacob, S. Winnerl, M. Fehrenbacher, J. Bhattacharyya, H. Schneider, M. T. Wenzel, H.-G. von Ribbeck, L. M. Eng, P. Atkinson, A. Rastelli, O. G. Schmidt, and M. Helm, Intersublevel spectroscopy on single InAs-quantum dots by terahertz near-field microscopy, Nano Letters 12, 4336-4340 (2012).
- M. Gensch et. al., Femtosecond level electron bunch diagnostic at quasi-cw SRF accelerators, Proceedings of IPAC2012, New Orleans (2012), MOPPR016
- N. Deßmann, S. G. Pavlov, V. N. Shastin, R. K. Zhukavin, S. Winnerl, M. Mittendorf, H.-W. Hübers, Time-resolved electronic capture in germanium doped with hydrogen-like impurity centers, Proceedings of the IEEE 37th International Conference on Infrared, Millimeter and Terahertz Waves, ID:2569425
- In collaboration with the Institute for Physics of Microstructures, Russian Academy of Sciences:
S. Morozov, M. Joludev, A. Antonov, V. Rumyantsev, V. Gavrilenko, V. Aleshkin, A. Dubinov, N. Mikhailov, S. Dvoretskiy, O. Drachenko, S. Winnerl, H. Schneider, M. Helm, Study of lifetimes and photoconductivity relaxation in heterostructures with HgxCd1-xTe-CdyHg 1-yTe quantum wells, Semiconductors 46, 1362 (2012)
- Using the Vertex 80v FTIR spectrometer at the HZDR, transmission characteristics of different THz filters, materials can be measured if requested by the partners of the PIDID collaboration.
- 08/2011: Pilotstepscanexperiments at the FUB (WP2)
- 07/2011: THz pump X-ray probe beamtime at FLASH (WP2, WP4)
- 04/2011: THz pump X-ray probe beamtime at FLASH (WP2, WP4)
- Budker Institute of Nuclear Physics (Budker)
- St. Petersburg State Polytechnical University (SPbSPU)
At FELBE, a set up for performing time-resolved and nanoscale microscopy and spectroscopy at low temperatures (WP1) will be developed. This instrument uniquely allows not only to investigate and image our samples of interest over the whole spectral range of the FELBE beamline with a sub-wavelength resolution (of a few 10 nm), but equally provides spectral fingerprints of individual molecules (proteins, charge-transfer molecules, polymers), Q-dots, or local dopants in semiconductor nanostructures and oxides, even for nanoscale buried structures. Of interest here is also the time-dependent decay of molecular and atomic excitations; this clearly shows the need and benefit of all the developments done within this project. The collaborations within the consortium therefore are very intense, covering THz issues with WP2, development of single-pulse detection for the nanoscale
inspection in WP5, time-resolved IR spectroscopy and 3D-mapping of IR bands (WP3) on selected samples (biological, oxides, etc.), as well as complementary macroscopic (WP4) and nanoscopic investigations (WP1) between FLASH and FELBE.
At FELBE a ps beamline (WP2) shall be implemented, providing narrow bandwidth THz pulses (0.4 – 2% FWHM), tunable in a spectral range between 66 and 1.2 THz and with pulse energies in the µJ regime as well as an adjustable repetition rate between 1 and 100 kHz to allow THz pump THz/VIS/ UV probe experiments on semiconductors, semiconductor nanostructures and complex oxides. This workpackage is lead by the HZDR although the required development of single-shot THz photon diagnostic and slicing of the MHz THz pulse trains is performed in close collaborations with DESY, UHH, TUB, UDE, TUKL, Budker Institute, LITP.
This beamline shall be combined with an endstation for time-resolved IR spectroscopy on proteins (WP3) consisting of a step-scan FT-IR difference spectroscopy set up with µs time resolution as well as a nonlinear optical set up for the ps time domain to allow for novel three-color UV-VIS/THz pump/ IR difference spectroscopy probe experiments with the tunable narrow band width THz pulses as selective pump for low energy excitations. This project is lead by the FUB who will transfer its expertise in the instrumentation development for time-resolved IR difference spectroscopy to FELBE and is collaborating with partners from HZDR, DESY, UDE, TUKL, Budker institute, LITP to develop an endstation for routine three-color user experiments with THz pump pulses tunable in the frequency range of 1.2 THz - 66 THz, UV-VIS pump pulses in a wavelength range of 300-700 nm and spectrally broad probe radiation in a frequency range between 1.2 - 66 THz.
The issue of different penetration depth of the Vis, THz and MIR radiation involved in the pilot experiment is overcome by a novel ATR (attenuated total reflection) set up, where the two pump beams, THz tunable between 1.2 and 66 THz from the FEL and 532 nm radiation from a table-top frequency-doubled Nd:YAG laser system irradiate the protein film from the top while the broadband infrared radiation from the globar source of the FT-IR spectrometer is probing the IR absorption by attenuated total reflection from inside the ATR prism.
First time-resolved step-scan measurements in transmission geometry have been performed with the FT-IR (Dr. C. Bauer, FUB). These time-resolved experiments were UV-VIS/THz pump/FT-IR probe experiments with the FEL as the master that triggered the visible excitation pulses. In order to be able to perform time-resolved two-colour pump/IR probe experiments the triggering scheme was developed, with which the visible laser pulses can be delayed against the FEL macro pulses. The FEL was used in the macro pulse mode (5 Hz, pulse length 100 µs) to avoid average heating of the water. The spatial and temporal overlap of the pulsed visible laser and the FEL macro pulses was achieved using a MCT detector, detecting both pump beams and observed on an oscilloscope. These two beams can be shifted against each other in time using a delay generator.
We performed step-scan experiments on samples of a thin layer of pure water in a cell using BaF2 windows, as internal water is thought to play an important role in bR. We also performed time-resolved UV-Vis/THz pump/IR probe spectroscopy of semi-dried films of bacteriorhodopsin. Experiments with and without irradiation by the FEL were performed, as well as experiments in which the FEL was delayed against the exciting Nd:YAG laser for several hundreds of µs. For the elucidation of a tentative effect more measurements have to be collected and averaged to improve the signal-to-noise ratio to elucidate a small change in the difference absorption spectra or the kinetics of distinct difference bands.
This transmission setup is available for regular user time-resolved FT-IR stepscan UV/Vis / THz pump/IR probe experiments
At FLASH implementation of the fs beamline (WP4) will provide instrumentation for truly synchronized fs pump probe experiments from soft X-rays to THz. More precisely, it will provide three tunable laser sources, one in the soft X-ray, one in the VIS/NIR and one in the THz spectral range. These lasers are mutually synchronized down to few 10s of fs. In addition this workpackage will provide control over the repetition rate of the THz pulses from 1Hz – 500 kHz within the FLASH burst. This tool will also provide control over the temporal pulse structure and its spectral bandwidth. This achievements will enable a novel class of experiments such as vibrational control of complex materials, which were impaired by limited FLASH capabilities. The required development of single-shot THz photon diagnostic and slicing of the MHz THz pulse train is performed in close collaborations with DESY, UHH, UDE, TUKL, TUB, Budker institute, and LITP.
Finally, to provide for the required single-pulse photon diagnostic and alignment of the temporal overlap, the TUB is leading the task for the development of single-pulse detectors (WP5) to be used at FLASH and FELBE and collaborating with partners from DESY, HZDR and the Budker institute. The TUB is furthermore the German contact of the Budker Institute in the development of an ultra broadband (THz – UV) imaging detector system based on a microbolometer array.