Research Projects

Attosecond science on metallic films

This project is heading for the extension of the methodologies of attosecond science to a broad range of surface science samples and especially plasmonic surfaces and structures. Previous studies have analysed the time-delayed photoemission from different states of single-crystal solids [1, 2]. Typically these samples require careful preparation and characterization under UHV conditions, known from solid state experiments with synchrotron radiation for years.

Focussing on plasmonic exitation there is a number of targets which cannot be prepared in this sense. Especially plasmonic nanostructures for which attosecond streaking could reveal electron dynamics in the time domain that is not accessible so far, are extremely sensitive on changes of geometry and roughness. Thus the demanding challenge is to find a way to overcome the preparation requirements used so far. The major goal is to utilize the high temporal resolution of the attosecond streaking method as a key technique to fully characterize plasmons in terms of propagation and especially creation [3].

Our current research focuses to extend the techniques of attosecond science towards experiments with optimized preparation techniques tailored for the sample types maintaining their plasmonic properties.

My group at CFEL has a long-standing collaboration with the Attosecond group at Imperial College London. In initial collaborative experiments carried out at Imperial College, we recently demonstrated breakthrough streaking measurements on polycrystalline and amorphous surfaces. Further experiments in this direction are underway at CFEL and Imperial College.

Attosecond Streaking on WO3 from [4]
[1] A. L. Cavalieri, N. Müller, Th. Uphues, V. S. Yakovlev, A. Baltuska, B. Horvath, B. Schmidt, L. Blümel, R. Holzwarth, S. Hendel, M. Drescher, U. Kleineberg, P. M. Echenique, R. Kienberger, F. Krausz, and U. Heinzmann, Nature 449, 1029-1032 (2007)
[2] S. Neppl, R. Ernstorfer, E. M. Bothschafter, A. L. Cavalieri, D. Menzel, J. V. Barth, F. Krausz, R. Kienberger, and P. Feulner, Phys. Rev. Lett. 109, 087401 (2012)
[3] E. Skopalová, D. Y. Lei, T. Witting, C. Arrell, F. Frank, Y. Sonnefraud, S. A. Maier, J. W. G. Tisch and J. P. Marangos, N. J. Phys. 13, 083003 (2011)
[4] W. A. Okell, T. Witting, D. Fabris, C. A. Arrell, J. Hengster, S. Ibrahimkutty, A. Seiler, M. Barthelmess, S. Stankov, D. Y. Lei, Y. Sonnefraud, M. Rahmani, T. Uphues, S. Maier, J. P. Marangos and J. W. G. Tisch, Optica 2, 383 (2015)

Attosecond science on hybrid nanostructures and plasmonic systems

Ultrafast time-resolved surface chemistry - Attosecond Surface ESCA

Preparation and characterisation of plasmonic nanoparticles for PES

FLUPi - Fluorescent Characterization of Ultrashort Pulses in the Near- and Infrared

The generation and characterization of intense few-cycle laser pulses is essential for various applications like the generation of isolated attosecond XUV pulses. With respect to current developments in laser physics it becomes even more difficult to characterize pulses in the non-visible wavelength range. The goal of this project is the further development of alternative and simple route for ultra-short laser pulse characterization utilizing the propagation in fluorescent liquid dye cells and dye enhanced polymers in particular.

An ultrafast laser pulse exhibits a substantial pulse broadening during propagation through a medium dominated by GVD of the medium. This results in a fluorescent trace with decreasing intensity along the propagation axis which is proportional to the local pulse duration in the medium. This enables the complete characterization of ultra-short laser pulses and determines even the sign of an existing chirp.

Since the fluorescence lifetime is in the order of a few nanoseconds this method can also serve for insitu single shot pulse measurement by following the peak intensity and position without any electronic data processing and is a powerful adjustment tool in the few-cycle regime.

The complete characterization of new dye labeled polymers for laser pulse characterization as a new and reliable tool is the primary goal of the project FLUPi.





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