Time-resolved ARPES at 88 MHz repetition rate with full 2π collection - Video Conference (for conference link write to Ralph Ernstorfer)
- Date: Mar 12, 2020
- Time: 14:00
- Speaker: Prof. Thomas Allison
- Stony Brook University, NY
- Location: Richard Willstätter House
- Room: Seminar Room
- Host: Physical Chemistry
- Contact: email@example.com
These limitations have severely restricted the range of samples and phenomena that can be studied with ultrafast tr-ARPES.
At Stony Brook, we have constructed a next-generation tr-ARPES instrument that addresses this data-rate challenge. We realize a high repetition rate ultrashort-pulse XUV light source using frequency comb methods and the technique of cavity-enhanced high harmonic generation CE-HHG. With a relatively simple and compact setup, the light source delivers to the sample >10 photons/s in well-isolated harmonics over a broad photon energy tuning range of 18-37 eV with a spot size of 58 × 100 μm [1-3]. The high repetition rate enables space-charge-free tr-ARPES experiments with nano-Ampere sample currents. From photoelectron spectroscopy data, we place conservative upper limits on the XUV pulse duration and photon-energy bandwidth of 93 fs and 65 meV, respectively. The light source has now been integrated with a time-of-flight momentum microscope , enabling efficient, parallel, momentum-resolved detection of the full 2π emission hemisphere from the surface under study. I will discuss preliminary results with this new instrument, ongoing tr-ARPES experiments, and also continuing development of the instrument. In particular, I will focus on tr-ARPES measurements from micron-scale sample areas and tr-ARPES measurements with perturbative pump excitation to study the intrinsic quasi-particle dynamics of materials.
 X. L. Li, M. A. R. Reber, C. Corder, Y. Chen, P. Zhao, and T. K. Allison. Rev. Sci. Inst. 87, 093114 (2016).
 C. Corder, P. Zhao, J. Bakalis, X. L. Li, M. D. Kershis, A. R. Muraca, M. G. White, and T. K. Allison, Structural Dynamics 5, 054301 (2018).
 C. Corder, P. Zhao, J. Bakalis, X. L. Li, M. D. Kershis, A. R. Muraca, M. G. White, and T. K. Allison. Development of a tunable high repetition rate XUV source for time-resolved photoemission studies of ultrafast dynamics at surfaces. Proceedings SPIE 10519, LAMOM XXIII, 105190B (2018). DOI:10.1117/12.2295232.
 K. Medjanik, O. Fedchenko, S. Chernov, D. Kutnyakhov, M. Ellguth, A. Oelsner, B. Schonhense, T. R. F. Peixoto, P. Lutz, C. H. Min, F. Reinert, S. Daster, Y. Acremann, J. Viefhaus, W. Wurth, H. J. Elmers, and G. Schonhense. Nat. Mater. 16, 615–621 (2017).