TY  - JOUR
A1  - Sander, Mathias
A1  - Herzog, Marc
A1  - Pudell, Jan-Etienne
A1  - Bargheer, Matias
A1  - Weinkauf, N.
A1  - Pedersen, M.
A1  - Newby, G.
A1  - Sellmann, J.
A1  - Schwarzkopf, J.
A1  - Besse, V.
A1  - Temnov, V. V.
A1  - Gaal, P.
T1  - Spatiotemporal Coherent Control of Thermal Excitations in Solids
JF  - Physical review letters
N2  - X-ray reflectivity measurements of femtosecond laser-induced transient gratings (TG) are applied to demonstrate the spatiotemporal coherent control of thermally induced surface deformations on ultrafast time scales. Using grazing incidence x-ray diffraction we unambiguously measure the amplitude of transient surface deformations with sub-angstrom resolution. Understanding the dynamics of femtosecond TG excitations in terms of superposition of acoustic and thermal gratings makes it possible to develop new ways of coherent control in x-ray diffraction experiments. Being the dominant source of TG signal, the long-living thermal grating with spatial period. can be canceled by a second, time-delayed TG excitation shifted by Lambda/2. The ultimate speed limits of such an ultrafast x-ray shutter are inferred from the detailed analysis of thermal and acoustic dynamics in TG experiments.
Y1  - 2017
U6  - https://doi.org/10.1103/PhysRevLett.119.075901
SN  - 0031-9007
SN  - 1079-7114
VL  - 119
SP  - 102
EP  - 110
PB  - American Physical Society
CY  - College Park
ER  - 
TY  - JOUR
A1  - Sander, Mathias
A1  - Koc, A.
A1  - Kwamen, C. T.
A1  - Michaels, H.
A1  - Reppert, Alexander von
A1  - Pudell, Jan-Etienne
A1  - Zamponi, Flavio
A1  - Bargheer, Matias
A1  - Sellmann, J.
A1  - Schwarzkopf, J.
A1  - Gaal, P.
T1  - Characterization of an ultrafast Bragg-Switch for shortening hard x-ray pulses
JF  - Journal of applied physics
N2  - We present a nanostructured device that functions as photoacoustic hard x-ray switch. The device is triggered by femtosecond laser pulses and allows for temporal gating of hard x-rays on picosecond (ps) timescales. It may be used for pulse picking or even pulse shortening in 3rd generation synchrotron sources. Previous approaches mainly suffered from insufficient switching contrasts due to excitation-induced thermal distortions. We present a new approach where thermal distortions are spatially separated from the functional switching layers in the structure. Our measurements yield a switching contrast of 14, which is sufficient for efficient hard x-ray pulse shortening. The optimized structure also allows for utilizing the switch at high repetition rates of up to 208 kHz. Published by AIP Publishing.
Y1  - 2016
U6  - https://doi.org/10.1063/1.4967835
SN  - 0021-8979
SN  - 1089-7550
VL  - 120
PB  - American Institute of Physics
CY  - Melville
ER  -