نتایج جستجو برای: ultrafast phenomenon
تعداد نتایج: 170044 فیلتر نتایج به سال:
PURPOSE To evaluate the diagnostic potential of three-dimensional image processing of ultrafast CT sialography in comparison with conventional CT sialography in patients with parotid masses. METHODS In nine patients, CT sialography was done with three-dimensional image processing. The visibility of anatomic details and pathologic findings, derived from three-dimensional images, were graded nu...
Structural rearrangements within single molecules occur on ultrafast time scales. Many aspects of molecular dynamics, such as the energy flow through excited states, have been studied using spectroscopic techniques, yet the goal to watch molecules evolve their geometrical structure in real time remains challenging. By mapping nuclear motions using femtosecond x-ray pulses, we have created real-...
Ultrafast CMR to deliver high volume screening of an at risk thalassemia population in the developing world: preliminary results from the TIC-TOC study (Thailand and UK international collaboration in thalassaemia using an optimised ultrafast CMR protocol) Amna Abdel-Gadir, Yongkasem Vorasettakarnkij, Hataichanok Ngamkasem, Sabrina Nordin, Emmanuel O Ako, Monravee Tumkosit, Pranee Sutcharitchan,...
A novel way to induce ultrafast currents in molecular wires using two incident laser frequencies, omega and 2omega, is demonstrated. The mechanism relies on Stark shifts, instead of near-resonance photon absorption, to transfer population to the excited states and exploits the temporal profile of the field to generate phase-controllable transport. Calculations in a trans- polyacetylene oligomer...
We demonstrate the possibility of a selective nonequilibrium cap opening of carbon nanotubes as a response to femtosecond laser excitation. By performing molecular dynamics simulations based on a microscopic electronic model we show that the laser-induced ultrafast structural changes differ dramatically from the thermally induced dimer emission. Ultrafast bond weakening and simultaneous excitat...
In this paper we numerically investigate the effect of relative phase on thestability of temporal bright solitons in a Nano PT- Symmetric nonlinear directionalcoupler (NLDC) by considering gain in bar and loss in cross. We also study the effect ofrelative phase on the output perturbed bright solitons energies, in the range of 0 to 180 . By using perturbation theory three eigenfunctions an...
The photolysis of diiododifluoromethane (CF(2)I(2)) in condensed phases was studied by a combination of matrix isolation and ultrafast time-resolved spectroscopy, in concert with ab initio calculations. Photolysis at wavelengths of 355 or 266 nm of CF(2)I(2):Ar samples (1:5000) held at approximately 8 K yielded iso-CF(2)I(2) (F(2)C-I-I), a metastable isomer of CF(2)I(2), characterized here for ...
1. Current OTDM Component Technology The large and ultrafast optical nonlinearity of millimeter-size semiconductor optical amplifiers (SOAs) has led to the study of several types of gate functions at ultrahigh bit-rates beyond 40 Gb/s. Among these functions, optical demultiplexing has been the most successfully demonstrated with 336 Gb/s RZ signals [1]. The slow-recovery-induced phenomena that ...
Unravelling the main initial dynamics responsible for chiral recognition is a key step in the understanding of many biological processes. However, this challenging task requires a sensitive enantiospecific probe to investigate molecular dynamics on their natural femtosecond time scale. Here we show that, in the gas phase, the ultrafast relaxation dynamics of photoexcited chiral molecules can be...
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