BES - SLAC Group/Department Public Websites - Stanford University

FYO7 SLAC S CIENCE AND T ECHNOLOGY S ELF E VALUATION
London, David A. Shapiro, Center for Biophotonics Science and Technology, University
of California, Davis; David van der Spoel, Florian Burmeister, Magnus Bergh, Carl
Caleman, Gösta Huldt, Marvin Seibert, Filipe R. N. C. Maia, Richard W. Lee, Abraham
Szöke, Nicusor Timneanu, Laboratory of Molecular Biophysics, Department of Cell and
Molecular Biology, Uppsala University; Elke Plönjes, Marion Kuhlmann, Rolf Treusch,
Stefan Düsterer, Thomas Tschentscher, Jochen R. Schneider, DESY, Eberhard Spiller,
Spiller X-ray Optics, Livermore, California ; Thomas Möller, Christoph Bostedt, Matthias
Hoener, Institut für Optik und Atomare Physik, Technische Universität Berlin.
N OTEWORTHY P RACTICES
Ultrafast Summer School
This summer school provided an important means by which PULSE can provide leadership in future
scientific directions associated with ultrafast science.
High Harmonics
We concentrate on the relation between the electronic orbitals of the molecules and the emitted high
harmonic amplitude and phase, for which we established novel measurement schemes with a
reference radiator. The information can be used to image the molecular orbitals.
CEP
We would like to invest more energy in the future to gain more control over the pulse shape on one
hand, and create single attosecond pulses instead of a train on the other hand. We plan to attack the
first aim by writing specific electronic, vibrational and rotational coherence on the molecule by
visible and UV light that can all be used to control the attosecond pulse shape. The second approach
can be achieved by using few cycle pulses and combining them with spectral selection in the
attosecond pulse spectrum or by use of polarization gating in the generation process. The attosecond
science will also have a tremendous impact on LCLS research, as stated above. The production of
CEP locked pulses in the few cycle regimes is necessary to produce well defined pulses below 1 fs
from LCLS. We are training people in this lab on technological and scientific issues of attosecond
science before LCLS has started to run.
Magnetic Nanostructures
Recently we found a way to numerically simulate the possible switching processes and mapped the
simulations to experimental data. This leads to a unified picture of magnetization reversal by spin
injection. The different nonuniform states can be described by magnetic vortex cores that are either
real inside the samples or virtual outside the sample. The motion of these vortex cores describes the
switching mechanism and switching dynamics. Analytic calculations show that magnetization
reversal by spin injection amplifies magnetic nonuniformities.
O PPORTUNITIES FOR I MPROVEMENT
Attoscience
Almost all experiments so far used the attosecond streak camera idea: electrons are emitted by an
attosecond pulse and gain kinetic energy in an overlapped strong IR field. The electron energy can be
correlated to their time of birth, and such a time trace of electron emission can be constructed. The
technique is applicable to diluted gases and surfaces only. It will therefore be important for the future
of attoscience to get a broader range of experimental schemes.
High Harmonics
In the future we will work on more complicated molecules that can undergo a prototype chemical
process in passing a CI between different electronic states. High harmonic imaging will be an ideal
tool to follow very fast changes in the electronic orbitals. In all those studies, we are already
generating trains of attosecond pulses, and since they are generated in molecules, they are shaped in
amplitude and phase.
F I N A L P A G E 2 3