@article{GaalSchickHerzogetal.2014, author = {Gaal, Peter and Schick, Daniel and Herzog, Marc and Bojahr, Andre and Shayduk, Roman and Goldshteyn, Jevgeni and Leitenberger, Wolfram and Vrejoiu, Ionela and Khakhulin, Dmitry and Wulff, Michael and Bargheer, Matias}, title = {Ultrafast switching of hard X-rays}, series = {Journal of synchrotron radiation}, volume = {21}, journal = {Journal of synchrotron radiation}, publisher = {Wiley-Blackwell}, address = {Hoboken}, issn = {0909-0495}, doi = {10.1107/S1600577513031949}, pages = {380 -- 385}, year = {2014}, abstract = {A new concept for shortening hard X-ray pulses emitted from a third-generation synchrotron source down to few picoseconds is presented. The device, called the PicoSwitch, exploits the dynamics of coherent acoustic phonons in a photo-excited thin film. A characterization of the structure demonstrates switching times of <= 5 ps and a peak reflectivity of similar to 10(-3). The device is tested in a real synchrotron-based pump-probe experiment and reveals features of coherent phonon propagation in a second thin film sample, thus demonstrating the potential to significantly improve the temporal resolution at existing synchrotron facilities.}, language = {en} } @article{HuLinMetwallietal.2023, author = {Hu, Neng and Lin, Li and Metwalli, Ezzeldin and Bießmann, Lorenz and Philipp, Martine and Hildebrand, Viet and Laschewsky, Andr{\´e} and Papadakis, Christine M. and Cubitt, Robert and Zhong, Qi and M{\"u}ller-Buschbaum, Peter}, title = {Kinetics of water transfer between the LCST and UCST thermoresponsive blocks in diblock copolymer thin films monitored by in situ neutron reflectivity}, series = {Advanced materials interfaces}, volume = {10}, journal = {Advanced materials interfaces}, number = {3}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {2196-7350}, doi = {10.1002/admi.202201913}, pages = {11}, year = {2023}, abstract = {The kinetics of water transfer between the lower critical solution temperature (LCST) and upper critical solution temperature (UCST) thermoresponsive blocks in about 10 nm thin films of a diblock copolymer is monitored by in situ neutron reflectivity. The UCST-exhibiting block in the copolymer consists of the zwitterionic poly(4((3-methacrylamidopropyl)dimethylammonio)butane-1-sulfonate), abbreviated as PSBP. The LCST-exhibiting block consists of the nonionic poly(N-isopropylacrylamide), abbreviated as PNIPAM. The as-prepared PSBP80-b-PNIPAM(400) films feature a three-layer structure, i.e., PNIPAM, mixed PNIPAM and PSBP, and PSBP. Both blocks have similar transition temperatures (TTs), namely around 32 degrees C for PNIPAM, and around 35 degrees C for PSBP, and with a two-step heating protocol (20 degrees C to 40 degrees C and 40 degrees C to 80 degrees C), both TTs are passed. The response to such a thermal stimulus turns out to be complex. Besides a three-step process (shrinkage, rearrangement, and reswelling), a continuous transfer of D2O from the PNIPAM to the PSBP block is observed. Due to the existence of both, LCST and UCST blocks in the PSBP80-b-PNIPAM(400 )film, the water transfer from the contracting PNIPAM, and mixed layers to the expanding PSBP layer occurs. Thus, the hydration kinetics and thermal response differ markedly from a thermoresponsive polymer film with a single LCST transition.}, language = {en} }