@article{SokolowskiTintenBlomeBlumsetal., author = {Sokolowski-Tinten, Klaus and Blome, Christian and Blums, Juris and Dietrich, Clemens and Tarsevitch, Alexander and Horn-von Hoegen, Michael and von der Linde, Dietrich and Cavalleri, Andrea and Kammler, Martin and Uschmann, Ingo and Foerster, Eckhart}, title = {Femtosecond X-ray Diffraction Study of Large Amplitude Coherent Optical Phonons in Laser-Excited Bismuth}, series = {Conference on Lasers and Electro-Optics, 1-6 June 2003, Baltimore, Maryland}, journal = {Conference on Lasers and Electro-Optics, 1-6 June 2003, Baltimore, Maryland}, publisher = {Optical Society of America}, abstract = {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.}, language = {en} } @article{SokolowskiTintenBlomeBlumsetal., author = {Sokolowski-Tinten, Klaus and Blome, Christian and Blums, Juris and Cavalleri, Andrea and Dietrich, Clemens and Tarasevitch, Alexander and Uschmann, Ingo and F{\"o}rster, Eckhard and Kammler, Martin and Horn-von Hoegen, Michael and von der Linde, Dietrich}, title = {Femtosecond X-ray measurement of coherent lattice vibrations near the Lindemann stability limit}, series = {Nature}, volume = {422}, journal = {Nature}, number = {6929}, publisher = {Springer}, doi = {10.1038/nature01490}, pages = {287 -- 289}, abstract = {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.}, language = {en} } @article{LuNicoulShymanovichetal., author = {Lu, Wei and Nicoul, Matthieu and Shymanovich, Uladzimir and Tarsevitch, Alexander and Kammler, Martin and Horn-von Hoegen, Michael and von der Linde, Dietrich and Sokolowski-Tinten, Klaus}, title = {Extreme Phonon Softening in Laser-excited Bismuth - Towards an Inverse Peierls-transition}, series = {MRS Online Proceedings Library}, volume = {1230}, journal = {MRS Online Proceedings Library}, publisher = {Springer}, doi = {10.1557/PROC-1230-MM03-05}, abstract = {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.}, language = {en} } @article{SokolowskiTintenBlomeDietrichetal., author = {Sokolowski-Tinten, Klaus and Blome, Christian and Dietrich, Clemens and Tarasevitch, A. and Horn-von Hoegen, Michael and von der Linde, D. and Cavalleri, Andrea and Squier, Jeff A. and Kammler, Martin}, title = {Femtosecond x-ray measurement of ultrafast melting and large acoustic transients}, series = {Physical review letters}, volume = {87}, journal = {Physical review letters}, publisher = {APS}, doi = {10.1103/PhysRevLett.87.225701}, abstract = {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.}, language = {en} } @article{SokolowskiTintenBlomeDietrichetal., author = {Sokolowski-Tinten, Klaus and Blome, Christian and Dietrich, Clemens and Tarasevitch, A. and Horn-von Hoegen, Michael and von der Linde, D. and Cavalleri, Andrea and Squier, Jeff A. and Kammler, Martin}, title = {Femtosecond time-resolved X-ray diffraction study of ultrafast structural dynamics in laser-excited solids}, series = {International Conference on Ultrafast Phenomena, 12 May 2002, Vancouver Canada}, volume = {71}, journal = {International Conference on Ultrafast Phenomena, 12 May 2002, Vancouver Canada}, publisher = {Optica Publishing Grou}, doi = {10.1007/978-3-642-59319-2_10}, pages = {36 -- 38}, abstract = {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.}, language = {en} }