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61.
Zhang D. Rahmat-Samii Y. Fetterman H.R. Prakash S. Bunshah F.R. Eddy M. Nilsson J.L. 《Microwave Theory and Techniques》1993,41(6):1032-1036
The use of YBa2Cu3O7-x and Tl2CaBa2Cu2O8 high-temperature superconducting thin films to fabricate frequency selective surfaces (FSS) at millimeter-wave frequencies (75-110 GHz) is discussed. An analytical/numerical model was applied, using a Floquet expansion and the method of moments, to analyze bandstop superconducting frequency selective surfaces. Experimental results were compared with the model, and showed agreement with resonant frequency prediction with an accuracy of better than 1%. The use of the superconducting frequency selective surfaces as quasi-optical millimeter-wave bandpass filters was also demonstrated 相似文献
62.
An electrical negative frequency feedback scheme is applied to a semiconductor laser to improve its direct frequency modulation performance in an FSK transmitter. An error signal caused by imperfect FM response is extracted through heterodyne discrimination detection with a stable master laser and fed back to the FM semiconductor laser. 相似文献
63.
The structures of the six isomers of 2,3,5,6-tetramethyl-morpholine have been determined by means of proton nuclear magnetic resonance studies at 100 MHz. The spectra have been analysed in terms of spin–spin coupling constants and population distributions of the possible conformers at low temperatures. Also included in this paper are results from n.m.r. studies on the six 4-benzyl-2,3,5,6-tetramethylmorpholine derivatives, which give information about the stereochemistry of the methyl groups α to the amine group. 相似文献
64.
65.
Bertil Nilsson Robert E. Carter Kjell-Ivar Dahlqvist Jzsef Mrton 《Magnetic resonance in chemistry : MRC》1972,4(1):95-105
The temperature dependence of the three different methylene AB spectra due to the 1-, 3- and 5-neopentyl groups in 2-chloro-4-iodo, 2-bromo-4-iodo and 2-bromo-4-chloro-1,3,5-trineopentyl-benzene was studied by proton magenetic resonance measurements at 60 MHz. The identification of the lines of the AB quartets at low temperature was carried out on an HA-100 spectrometer by means of the INDOR technique. The activation parameters for all three barriers in each compound were found to be approximately the same, which perhaps reflects the interdependence of the rotations, with the smaller of the two halogens determining the size of the barrier. An explanation in terms of magnetic nonequivalence induced in the 1- and 5-methylenes by the 3-neopentyl group is considered to be most plausible. 相似文献
66.
Roy Nilsson Ralf Nyholm Anders Berndtsson Jan Hedman Carl Nordling 《Journal of Electron Spectroscopy and Related Phenomena》1976,9(4):337-353
A new source for producing YMξ radiation in an ESCA spectrometer is described. The system makes use of continuous evaporation of yttrium on a rotating anode. It is demonstrated that this scheme allows YMξ-excited electron spectra to be recorded without gradual loss of resolution and intensity due to anode oxidation. Electron spectra of Ar, Hg and N2 excited by YMξ radiation are studied. Relative photoelectric cross-sections of the 5d, 5d and 6s orbitals in Hg and the four valence orbitals in N2 are measured. The valence electron shake-up spectrum of N2 is discussed. 相似文献
67.
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70.
A. Berndtsson R. Nyholm R. Nilsson J. Hedman C. Nordling 《Journal of Electron Spectroscopy and Related Phenomena》1978,13(2):131-139
The applicability of the F Kα X-ray line (hv = 676 eV) from potassium fluoride for the excitation of electron spectra is demonstrated. Relative photoionization cross-sections in Au and gaseous Hg have been measured. The F Kα radiation from KF, RbF and CsF has been studied. The Ba Mζ line (hv = 602 eV) is found to be too broad for use in ESCA, even when emitted from metallic barium. 相似文献