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81.
82.
Horst Kessler Günther Becker Herbert Kogler Michael Wolff 《Tetrahedron letters》1984,25(36):3971-3974
2-(2-pyridyl-)ethyl esters are used as chemically inert, highly selective protecting groups that are removable under mild conditions via a two step procedure. 相似文献
83.
In this paper we give an exact solution of the coupled differential equation system as developed by Kogelnik [1] for the case of symmetrical recording without neglecting the second differentials. This generalized solution is applicable to dielectric, absorption and so-called mixed volume holograms. It is shown that under special assumptions and approximations we get the same equations for the diffraction efficiency as derived by Kogelnik. In this first part of the paper transmission holograms are only investigated and in the second part we will give the solution for reflection holograms. 相似文献
84.
Photoelectrons ejected from cesium atoms by circularly polarized light of certain wavelengths are highly spinpolarized according to Fano's theory. Measurements of the spinpolarization of photoelectrons along the wavelength spectrum are reported. The highest degree of spinpolarization obtained experimentally is 100%. Our results reveal a small deviation from the theoretically predicted spinpolarization. Apart from giving information on the influence of spin-orbit interaction on the photoionization process, the Fano-effect turns out to be a simple and efficient method for producing polarized electron beams. Though not designed as a polarized electron source, our present apparatus yields a beam of 0.3·10?10 Ampere with a polarization of 81 ± 3% when a broad unfiltered spectral band is irradiated. 相似文献
85.
86.
87.
U. Heinzmann K. Jost J. Kessler B. Ohnemus 《Zeitschrift für Physik A Hadrons and Nuclei》1972,251(4):354-364
The spin polarization of photoelectrons emitted by alkali surfaces illuminated with monochromatic circularly polarized radiation has been observed. Maximum spin polarization of 4.5% is obtained with cesium at a wavelength of about 4500 Å. Both maximum spin polarization and the wavelength of the maximum decrease monotonically with decreasing atomic number. The spin polarization is zero within experimental errors, in the case of solid sodium and lithium. 相似文献
88.
An apparatus and a procedure are described for the preconcentration of nanogram amounts of trace elements. Co-precipitation and pressure filtration confine the precipitate to a 1.27 mm diameter spot on a filter membrane. Trace elements in the 10-100 ng range are collected reproducibly and detected with high sensitivity by X-ray fluorescence, by use of a milliprobe instrument. Advantages of the technique for quantitative applications are discussed. 相似文献
89.
Zeitschrift für Physik A Hadrons and nuclei - Electrons with an initial energy of 100 keV have been shot through thin films of Ni, Ge, Ag and Au. The angular distribution of the plurally... 相似文献
90.