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481.
Femtosecond polarization pulse shaping   总被引:1,自引:0,他引:1  
Brixner T  Gerber G 《Optics letters》2001,26(8):557-559
We report computer-controlled femtosecond polarization pulse shaping where intensity, momentary frequency, and light polarization are varied as functions of time. For the first time to our knowledge, a pulse shaper is used to modulate the degree of ellipticity as well as the orientation of the elliptical principal axes within a single laser pulse by use of a 256-pixel two-layer liquid-crystal display inside a zero-dispersion compressor. Interferometric stability of the setup is not required. Complete pulse characterization is achieved by dual-channel spectral interferometry. This technology has a large range of applications, especially in the field of quantum control.  相似文献   
482.
4 are the constituents of a molecular beam. Of importance are parameters such as laser intensity, pulse duration, and laser wavelength for a quantitative characterization and thereby improvement of MBE sources. This would help to optimize the epitaxial growth process. We demonstrate that nonresonant multiphoton ionization (MPI) by fs laser pulses leads to detection of the parent molecule, whereas nonresonant MPI with ns laser pulses leads to strong fragmentation. Received: 8 August 1997/Revised version: 3 December 1997  相似文献   
483.
Experimental evidence is presented for the effect of electron energy loss on determining the type of cross field electron streaming instability that develops in low density, high temperature plasmas.  相似文献   
484.
Ion-beam induced attenuations of transient magnetic fields have been further studied in measurements on high-velocity24Mg- and28Si-ions as well as low-velocity48Ti-ions using energetic beams of Ti- and Br-ions. Further evidence for the stopping power dependence of the attenuations is found; more data in the threshold region of Fe-host support earlier observations. In Gd-host the attenuations are again weaker pronounced than in Fe in accordance with previous data.  相似文献   
485.
486.
The reactions58Ni+102Pd→160W and58Ni+106Cd→164Os were investigated to search for new decay data of neutron deficient nuclei. Excitation energies of the compound nuclei covered a range from 47 to 89 MeV. Velocity separation of the evaporation residues and position time correlations with the a decays of the implanted nuclei were used. The following new decay data were measured:162Os (Eα=(6611 ±30) keV, T1/2=(1.9±0.7) ms);158W (T1/2=(0.9±0.3) ms);158mW (E=1.88 MeV, Eα=(8280±30) keV, T1/2=(0.01-1) ms);155mLu (Eα=(5575±10) keV); β decay of156Ta (T1/2 > 10 ms) to the 8+ yrast isomer in156Hf. A cross section of 5μb was measured for the new isotope156Ta produced in a p3n evaporation channel from160W at 64 MeV excitation energy.  相似文献   
487.
Transient field precessions of the first excited 2+ and 4+ states in 20Ne nuclei traversing polarized gadolinium have been measured. The deduced g-factor of the 4+ state, g = + 0.08(20), agrees with our earlier reported value of g = ? 0.10(19) measured in iron by the same technique. The significant reduction in the value of the g-factor, g? = ? 0.01(14), relative to that of the 2 + state, g = + 0.54(4), is incompatible with the pure T = 0 character expected for low-lying states in this self-conjugate nucleus. In addition, the lifetime of the 4+ state has been measured to be τ = 95(13) fs, in agreement with a previous measurement.  相似文献   
488.
The performance of a KrF excimer laser, excited by a discharge produced in a quartz tube between two metallic electrodes at its end and the inner tube wall serving as a dielectric electrode, is described. The dielectric electrode is capacitively coupled to a metallic electrode surrounding the quartz tube coaxially. Laser output energies up to 0.9 mJ in pulses having a duration of 6 ns FWHM could be obtained at a driving voltage of 100 kV.  相似文献   
489.
A zero-entropy mixing transformationT is constructed such thatT×T is loosely Bernoulli (LB). Previously known examples were not mixing. The construction is then generalized to yield a zero-entropy mixing transformationT such that then-fold productT × … ×T is LB for each positive integern. Furthermore, a flow with the same properties is obtained.  相似文献   
490.
An apparatus to determine the reorientation kinetics of nematic liquid crystals in a magneticfield is described. Measurements of the rotational viscosity as a function of temperature are presented for several commercial mixtures composed of different classes of substances. An attempt is made to relate the data with some structural properties.  相似文献   
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