TY - JOUR A1 - Sokolowski-Tinten, Klaus A1 - Blome, Christian A1 - Blums, Juris A1 - Dietrich, Clemens A1 - Tarsevitch, Alexander A1 - Horn-von Hoegen, Michael A1 - von der Linde, Dietrich A1 - Cavalleri, Andrea A1 - Kammler, Martin A1 - Uschmann, Ingo A1 - Foerster, Eckhart T1 - Femtosecond X-ray Diffraction Study of Large Amplitude Coherent Optical Phonons in Laser-Excited Bismuth JF - Conference on Lasers and Electro-Optics, 1–6 June 2003, Baltimore, Maryland N2 - Femtosecond time-resolved X-ray diffraction was used to directly study optical phonons in laser-excited Bismuth. A periodic modulation of the diffraction efficiency reveals initially coherent lattice distortions with atomic displacements of nearly 10% of the nearest- neighbor-distance. Y1 - 2003 UR - https://opg.optica.org/abstract.cfm?uri=cleo-2003-CMZ6 PB - Optical Society of America ER - TY - JOUR A1 - Sokolowski-Tinten, Klaus A1 - Blome, Christian A1 - Blums, Juris A1 - Cavalleri, Andrea A1 - Dietrich, Clemens A1 - Tarasevitch, Alexander A1 - Uschmann, Ingo A1 - Förster, Eckhard A1 - Kammler, Martin A1 - Horn-von Hoegen, Michael A1 - von der Linde, Dietrich T1 - Femtosecond X-ray measurement of coherent lattice vibrations near the Lindemann stability limit JF - Nature N2 - The study of phase-transition dynamics in solids beyond a time-averaged kinetic description requires direct measurement of the changes in the atomic configuration along the physical pathways leading to the new phase. The timescale of interest is in the range 10(-14) to 10(-12) s. Until recently, only optical techniques were capable of providing adequate time resolution, albeit with indirect sensitivity to structural arrangement. Ultrafast laser-induced changes of long-range order have recently been directly established for some materials using time-resolved X-ray diffraction. However, the measurement of the atomic displacements within the unit cell, as well as their relationship with the stability limit of a structural phase, has to date remained obscure. Here we report time-resolved X-ray diffraction measurements of the coherent atomic displacement of the lattice atoms in photoexcited bismuth close to a phase transition. Excitation of large-amplitude coherent optical phonons gives rise to a periodic modulation of the X-ray diffraction efficiency. Stronger excitation corresponding to atomic displacements exceeding 10 per cent of the nearest-neighbour distance-near the Lindemann limit-leads to a subsequent loss of long-range order, which is most probably due to melting of the material. Y1 - 2003 U6 - https://doi.org/10.1038/nature01490 VL - 422 IS - 6929 SP - 287 EP - 289 PB - Springer ER - TY - INPR A1 - Cavalleri, Andrea A1 - Siders, Craig A1 - Toth, Csaba A1 - Squier, Jeff A. A1 - Barty, C. P. J. A1 - Wilson, K. R. A1 - Sokolowski-Tinten, Klaus A1 - von der Linde, Dietrich A1 - Kammler, Martin A1 - Horn- von Hoegen, Michael T1 - Measurement of harmonic and anharmonic semi-conductor-lattice dynamics with ultrafast x-ray diffraction N2 - Many fundamental processes in solids, such as heat transport and phase transitions involve atomic movement on ultrafast time-scales, but cannot be directly measured with visible light. Using ultrafast x-ray diffraction, atomic motion can be measured on its natural time-scale. Photo-excitation of bulk and layered semiconductors was achieved with 800-nm wavelength femtosecond laser pulses. Optical excitation triggers a chain of relaxation processes, causing rapid lattice heating, generation and propagation of stress/strain waves into the bulk and eventual anharmonic decay of coherent acoustic phonons into the thermal bath of the solid. While the first steps of carrier relaxation, excitation and decay of Raman-active optical phonons have been in the past characterized optically at surfaces, the bulk acoustic dynamics at longer times has not. We measure length scales of lattice excitation, thereby detecting ultrafast heat diffusion via fast electrons, coherent acoustic pulse propagation into the bulk or across buried interfaces and anharmonic damping of non-equilibrium acoustic phonons. The measurement is performed with sensitivity on lattice spacing of 10 femtometers (i.e., 3 nuclear diameters). Y1 - 2000 UR - https://www.researchgate.net/publication/252175863_Measurement_of_harmonic_and_anharmonic_semi-conductor-lattice_dynamics_with_ultrafast_x-ray_diffraction ER - TY - INPR A1 - Siders, Craig A1 - Cavalleri, Andrea A1 - Toth, Csaba A1 - Squier Jeff A., A1 - Barty, C. P. J. A1 - Wilson, K. R. A1 - Sokolowski-Tinten, Klaus A1 - von der Linde, Dietrich A1 - Kammler, Martin A1 - Horn- von Hoegen, Michael T1 - Ultrafast Nonthermal Melting of Femtosecond-laser-irradiated Germanium Measured by Ultrafast X-ray Diffraction N2 - Many fundamental processes in nature, such as chemical reactions and phase transitions involve rearrangement of the constituent atoms. Such changes cannot be directly measured with visible light and occur transiently on time-scales comparable with the natural oscillation periods of atoms (femtoseconds to picoseconds). We present experiments on Ge-111 films irradiated with 100-fs 800-nm light pulses and probed by a time-delayed sub-ps x-ray pulse at 8 keV. After excitation of a dense electron-hole plasma within the 160-nm film, the ultrafast pathway of lattice disordering is measured as a function laser fluence. For close-to-threshold irradiation, inhomogeneous thermal melting, occurring via surface nucleation of the liquid phase and growth into the bulk determines the dynamics of the solid-to-liquid phase transition. For excitation at about twice the melting threshold, a nonthermal pathway, starting from a highly excited cold solid and relaxing into a hot liquid causes ultrafast melting. At long time delays, nearly perfect recrystallization of a (111) crystal is observed. Y1 - 2000 UR - https://www.researchgate.net/publication/252159566_Ultrafast_Nonthermal_Melting_of_Femtosecond-laser-irradiated_Germanium_Measured_by_Ultrafast_X-ray_Diffraction ER - TY - JOUR A1 - Lu, Wei A1 - Nicoul, Matthieu A1 - Shymanovich, Uladzimir A1 - Tarsevitch, Alexander A1 - Kammler, Martin A1 - Horn-von Hoegen, Michael A1 - von der Linde, Dietrich A1 - Sokolowski-Tinten, Klaus T1 - Extreme Phonon Softening in Laser-excited Bismuth - Towards an Inverse Peierls-transition JF - MRS Online Proceedings Library N2 - Large amplitude coherent optical phonons have been investigated in laser-excited Bismuth by means of femtosecond time-resolved X-ray diffraction. For absorbed laser fluences above 2 mJ/cm2, the experimental data reveal an extreme softening of the excited A1g-mode down to frequencies of about 1 THz, only 1/3 of the unperturbed A1g-frequency. At even stronger excitation the measured diffraction signals no longer exhibit an oscillatory behavior presenting strong indication that upon intense laser-excitation the Peierls-distortion, which defines the equilibrium structure of Bismuth, can be transiently reversed. Y1 - 2009 U6 - https://doi.org/10.1557/PROC-1230-MM03-05 VL - 1230 PB - Springer ER - TY - CHAP A1 - Sokolowski-Tinten, Klaus A1 - Blome, Christian A1 - Dietrich, Clemens A1 - Blums, Juris A1 - Horn-von Hoegen, Michael A1 - von der Linde, D. A1 - Cavalleri, Andrea A1 - Squier, Jeff A. A1 - Kammler, Martin T1 - Structural dynamics in laser-excited solids investigated with femtosecond x-ray diffraction T2 - 2002 Summaries of Papers Presented at the Quantum Electronics and Laser Science Conference, 19-24 May 2002, Long Beach, CA, USA N2 - Summary form only given. Ultrashort x-ray pulses offer a unique combination of atomic-scale spatial and temporal resolution, which permits direct measurements of structural transients on an ultrafast time scale. Using time-resolved X-ray diffraction with femtosecond, multi-keV X-ray pulses we have studied transient lattice dynamics in optically excited semiconductors. Y1 - 2002 U6 - https://doi.org/10.1109/QELS.2002.1031182 SP - 115 EP - 116 PB - IEEE ER - TY - JOUR A1 - Sokolowski-Tinten, Klaus A1 - Blome, Christian A1 - Dietrich, Clemens A1 - Tarasevitch, A. A1 - Horn-von Hoegen, Michael A1 - von der Linde, D. A1 - Cavalleri, Andrea A1 - Squier, Jeff A. A1 - Kammler, Martin T1 - Femtosecond x-ray measurement of ultrafast melting and large acoustic transients JF - Physical review letters N2 - Time-resolved x-ray diffraction with ultrashort ( approximately 300 fs), multi-keV x-ray pulses has been used to study the femtosecond laser-induced solid-to-liquid phase transition in a thin crystalline layer of germanium. Nonthermal melting is observed to take place within 300-500 fs. Following ultrafast melting we observe strong acoustic perturbations evolving on a picosecond time scale. Y1 - 2001 U6 - https://doi.org/10.1103/PhysRevLett.87.225701 VL - 87 PB - APS ER - TY - JOUR A1 - Sokolowski-Tinten, Klaus A1 - Blome, Christian A1 - Dietrich, Clemens A1 - Tarasevitch, A. A1 - Horn-von Hoegen, Michael A1 - von der Linde, D. A1 - Cavalleri, Andrea A1 - Squier, Jeff A. A1 - Kammler, Martin T1 - Femtosecond time-resolved X-ray diffraction study of ultrafast structural dynamics in laser-excited solids JF - International Conference on Ultrafast Phenomena, 12 May 2002, Vancouver Canada N2 - Time-resolved x-ray diffraction with sub-300 fs, multi-keV x-ray pulses was used to study ultrafast lattice dynamics in laser-irradiated germanium and bismuth. In bismuth strong excitation of optical phonons is observed prior to disordering of the material. Y1 - 2002 U6 - https://doi.org/10.1007/978-3-642-59319-2_10 VL - 71 SP - 36 EP - 38 PB - Optica Publishing Grou ER - TY - CHAP A1 - Sokolowski-Tinten, Klaus A1 - Blome, Christian A1 - Blums, Juris A1 - Shymanovich, Uladzimir A1 - Nicoul, Matthieu A1 - Cavalleri, Andrea A1 - Tarasevitch, A. A1 - Horn-von Hoegen, Michael A1 - Kammler, Martin A1 - von der Linde, Dietrich ED - Kobayashi, Tetsuro T1 - Ultrafast X-ray diffraction T2 - Ultrafast Phenomena XIV N2 - In the last few years the generation of femtosecond pulses in the X-ray regime has become possible. These ultrashort X-ray pulses have enabled femtosecond time- resolution to be extended to X-rays. Y1 - 2004 SN - 978-3-540-27213-7 U6 - https://doi.org/10.1007/3-540-27213-5_53 VL - 79 SP - 170 EP - 174 PB - Springer CY - Berlin, Heidelberg ER -