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In a strong laser field, electrons tunnel from an atom at a rate determined by the instantaneous field. If the pulse is only a few cycles in duration, the highly nonlinear nature of tunnel ionization ensures that the resultant electron wave packet is primarily formed in less than one period. Measuring the direction of above-threshold-ionization electrons produced by circularly polarized light provides a direct method of measuring the absolute carrier phase of a single pulse. The method is robust, surviving spatial and temporal integration as well as intensity fluctuations. 相似文献
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The experimental realization of thermocapillary flow without return flow is reported. This type of flow (linear flow) was proposed and analyzed theoretically by Smith and Davis (J. Fluid Mech., 132:119–144, 1983). We suppressed the return flow by providing channels and side channels with lower flow resistance compared to that of the return flow. Cooling the layer with linear flow from above results in the Marangoni instability of longitudinal rolls as the most dangerous mode. Strong linear flow stabilizes the system against longitudinal rolls. We report preliminary results on the threshold and on the wavelength of the longitudinal rolls. 相似文献
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Stefanie Beck Dr. Michael Feller Laura Spies Kai J. Dietrich Christoph Jessen Dr. Karin Stierstorfer Prof. Dr. Andreas J. Kornath 《ChemistryOpen》2021,10(1):8-15
Abstract : γ-Butyrolactone and γ-butyrolactam were reacted in the superacidic systems XF/MF5 (X=H, D; M=As, Sb). Salts of the monoprotonated species of γ-butyrolactone were obtained in terms of [(CH2)3OCOH]+[AsF6]−, [(CH2)3OCOH]+[SbF6]− and [(CH2)3OCOD]+[AsF6]− and the analogous lactam salts in terms of [(CH2)3NHCOH]+[AsF6]−, [(CH2)3NHCOH]+[SbF6]− and [(CH2)3NDCOD]+[AsF6]−. The salts were characterized by low temperature Raman and infrared spectroscopy and for both protonated hexafluoridoarsenates, [(CH2)3OCOH]+[AsF6]− and [(CH2)3NHCOH]+[AsF6]−, single-crystal X-ray structure analyses were conducted. In addition to the experimental results, quantum chemical calculations were performed on the B3LYP/aug-cc-pVTZ level of theory. As in both crystal structures C⋅⋅⋅F contacts were observed, the nature of these contacts is discussed with Mapped Electrostatic Potential as a rate of strength. 相似文献