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30.04.2014, 15:30 Uhr

Klasse für Naturwissenschaften und Medizin, 558. Sitzung

Prof.'in Dr. Ursula Keller, Zürich: "Attoclock: shining new light on old questions in quantum mechanics"; Prof.'in Dr. Tanja Weil, Ulm: "Schaltbare Präzisionspolymere für Biomedizinische Anwendungen"

Prof.'in Dr. Ursula Keller
Ursula Keller, a tenured professor of physics at ETH since 1993, leads the Ultrafast Laser Physics group, and currently also serves as a director of the Swiss multi-institute NCCR MUST program in ultrafast science since 2010. Born 1959 in Zug, Switzerland, she received the Physics "Diplom" from ETH Zurich in 1984 and the Ph.D. in Applied Physics from Stanford University, USA in 1989. She was a Member of Technical Staff (MTS) at AT&T Bell Laboratories in New Jersey from 1989 to 1993. She was a “Visiting Miller Professor” at UC Berkeley in 2006 and a visiting professor at the Lund Institute of Technologies in 2001. She has been a co-founder and board member for Time-Bandwidth Products since 1995 and for GigaTera from 2000 to 2003, a venture capital funded telecom company during the “bubble phase” which was acquired by Time-Bandwidth in 2003. Her research interests are exploring and pushing the frontiers in ultrafast science and technology: ultrafast solid-state and semiconductor lasers, ultrashort pulse generation in the one to two optical cycle regime, frequency comb generation and stabilization, reliable and functional instrumentation for extreme ultraviolet to X-ray generation, attosecond experiments using high harmonic generation, and attosecond sience. Awards include the Arthur L. Schawlow Award 2013, the highest achievement award of the Laser Institute of America (LIA), the ERC advanced grant in 2012, EPS Senior Prize in 2011 “for seminal contributions to ultrafast solid-state lasers, telecom, metrology, and attosecond science”, the OSA Fraunhofer/Burley Prize 2008, the Leibinger Innovation Prize 2004, and the Zeiss Research Award 1998. The Thomson Citation Index ranked her as the third-place top-cited researcher during the decade 1991-99 in optoelectronics. OSA Fellow, EPS Fellow, member of the Royal Swedish Academy of Sciences, the Academy Leopoldina and the Swiss Academy of Techical Sciences, more than 350 peerreviewed journal publications, and as of Sept. 2013 with >14’000 citations and an h-index of 62 (Web of Science), she has published >200 invited, 18 plenary, 12 keynote, and 8 tutorial talks at international conferences.

Aus dem Inhalt des Vortrages
Attoclock: shining new light on old questions in quantum mechanics

Novel time-resolved attosecond streaking techniques such as energy streaking [1] and the attoclock (i.e. angular streaking) [2, 3] are currently being applied in an attempt to answer a very fundamental questions in quantum mechanics, such as how fast can light remove a bound electron from an atom or a solid? Furthermore, the question of how long a tunneling particle spends inside the barrier has remained unresolved since the early days of quantum mechanics. The main theoretical contenders, such as the Buttiker-Landauer, the Eisenbud-Wigner (also known as Wigner-Smith), and the Larmor time give contradictory answers. Yet recent attempts at reconstructing valence electron dynamics in atoms and molecules have entered a regime where the tunneling time genuinely matters. Therefore it is often posited that the tunneling time is instantaneous because both the Keldysh and the related Buttiker-Landauer times are imaginary (corresponding to the decay of the wavefunction under the barrier). At the other extreme, it is often suggested that quantum mechanical uncertainty precludes a deterministic tunneling time, so little can be said. We used the attoclock technique to measure the tunneling delay time in strong laser field ionization of helium and reveal a real and not instantaneous tunneling time. The matching theoretical model predicts a strong implications on the investigation of electron dynamics in attosecond science, because a significant delay must be taken into account about when the electron hole dynamics begin to evolve [4].
1. P. Eckle et al., Nat. Phys. 4, 565 (2008).
2. R. Kienberger et al., Nature 427, 817 (2004).
3. P. Eckle et al., Science 322, 1525 (2008).
4. A. S. Landsman et al., arXiv:1301.2766 [physics.atom-ph] 13. Jan. 2013

Prof.'in Dr. Tanja Weil
liegt noch nicht vor

Aus dem Inhalt des Vortrages
Schaltbare Präzisionspolymere für Biomedizinische Anwendungen

Biomakromoleküle wie Proteine, Peptide und Oligonukleotide besitzen präzise definierte Molekulargewichte, Monomersequenzen und dreidimensionale Architekturen. Ihre hohe strukturelle Präzision ist für ihre biologische Aktivität unabdingbar. Bislang gelingt es nicht, synthetische Polymere mit einem vergleichbaren Maß an struktureller Genauigkeit herzustellen.
Wir haben einen Zugang zu Copolymeren ausgehend von nativen Proteinen erschlossen, die sich durch eine exakte Monomerabfolge, eine definierte Kettenlänge sowie einer Vielzahl funktioneller Gruppen entlang des Polypeptidgerüsts auszeichnen. Derartige Polymere eignen sich insbesondere für den Transport und die Freisetzung von Wirkstoffen und bieten neue Ansätze für die personalisierte Medizin.
Ferner eröffnet die Selbstorganisation von synthetischen Makromolekülen und Proteinen einen Zugang zu einzigartigen Hybridstrukturen, deren Eigenschaften sich additiv oder sogar synergistisch aus den jeweiligen Monomerbausteinen ergeben. Auf diesem Weg lassen sich beispielsweise supramolekulare Fusionsproteine herstellen, die in der Zelle spontan zerfallen und es konnten schaltbare Proteasen synthetisiert werden, deren katalytische Aktivität über ihre supramolekulare Struktur gesteuert wird. Diese intelligenten Makromoleküle reagieren mit einer strukturellen Anpassung auf Veränderungen in Ihrer Umgebung, was insbesondere für biomedizinische Anwendungen von Interesse ist.

References
[1] Wu, Y.; Chakrabortty, S.; Gropeanu, R. A.; Wilhelmi, J.; Yang, X.; Er, K. S.; Kuan, S. L.; Koynov, K.; Chan, Y.; Weil, T. J. Am. Chem Soc. 2010, 132, 14, 5012–5014.
[2] Ng, Y.W.D.; Arzt, M.; Wu, Y.; Kuan, S.L.; Lamla, M.; Weil, T. Angew. Chem. Int. Ed. 2013, Accepted, DOI: 10.1002/anie.201308533.
[3] Kuan, S.L.; Ng, Y.W.D.; Wu, Y.; Förtsch, C.; Barth, H.; Doroshenko, M.; Koynov, K.; Meier, C.; Weil, T. J. Am. Chem. Soc. 2013, accepted, DOI: 10.1021/ja4084122.