نتایج جستجو برای: ultrafast phenomenon
تعداد نتایج: 170044 فیلتر نتایج به سال:
We fabricate a free-standing few-layer molybdenum disulfide (MoS2)-polymer composite by liquid phase exfoliation of chemically pristine MoS2 crystals and use this to demonstrate a wideband tunable, ultrafast mode-locked fiber laser. Stable, picosecond pulses, tunable from 1535 nm to 1565 nm, are generated, corresponding to photon energies below the MoS2 material bandgap. These results contribut...
Ultrafast optical lasers play an essential role in exploiting the unique capabilities of recently commissioned X-ray free-electron laser facilities such as the Linac Coherent Light Source (LCLS). Pump-probe experimental techniques reveal ultrafast dynamics in atomic and molecular processes and reveal new insights in chemistry, biology, material science and high-energy-density physics. This manu...
Introduction Until recently, in utero fetal magnetic resonance imaging (MRI) had minimal clinical utility due to marked interference from motion artifacts. Technical advances in the MR soft (ultrafast sequences) and hard ware (fast gradients, surface coils) now allow to apply MRI for prenatal diagnosis. The aim of this study was to evaluate the ultrafast, T2weighted single shot fast spin-echo (...
We demonstrate integrated semiconductor optical devices with ultrafast temporal responses based on the plasma-dispersion effect. The geometry of the devices removes the dependence of the modulation time on the free-carrier dynamics. We present the theoretical analysis of the performance of such devices. We show that a silicon-based device with a free-carrier lifetime of 1.4 ns can be modulated ...
The authors time resolve molecular motion in bound state, ionic potentials that leads to bond cleavage during the interaction with intense, ultrafast laser fields. Resonances in molecular ions play an important role in dissociative ionization with ultrafast laser fields, and the authors demonstrate how these resonances evolve in time to produce dissociation after initial strong-field ionization...
The ultrafast relaxation of small clusters immediately after ionization is studied. For small Hgn clusters we determine the fragmentation-time distributions induced by ionization. A dramatic change of the fragmentation behaviour occurs when the temperature before ionization reaches the melting point of the neutral clusters. The ultrafast dynamics depends nonlinearly on initial conditions regard...
1 Physical Biology Center for Ultrafast Science and Technology, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, CA 91125, USA 2Laboratory of Ultrafast Spectroscopy, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland 3MIT Department of Physics, 77 Mass. Avenue, Bldg. 13-2114 Cambridge, MA 02139, USA 4SMC-ISC-CNR, Department...
One-dimensional SnO₂- and Li⁺-doped SnO₂ porous nanofibers were easily fabricated via electrospinning and a subsequent calcination procedure for ultrafast humidity sensing. Different Li dopant concentrations were introduced to investigate the dopant's role in sensing performance. The response properties were studied under different relative humidity levels by both statistic and dynamic tests. T...
During ultrafast demagnetization of a magnetically ordered solid, angular momentum has to be transferred between the spins, electrons, and phonons in the system on femto- and picosecond timescales. Although the intrinsic spin-transfer mechanisms are intensely debated, additional extrinsic mechanisms arising due to nanoscale heterogeneity have only recently entered the discussion. Here we use fe...
The ability to record images with extreme temporal resolution enables a diverse range of applications, such as fluorescence lifetime imaging, time-of-flight depth imaging and characterization of ultrafast processes. Recently, ultrafast imaging schemes have emerged, which require either long acquisition times or raster scanning and have a requirement for sufficient signal that can only be achiev...
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