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61.
G. Bánó L. Szalai K. Kutasi P. Hartmann Z. Donkó K. Rózsa Á. Kiss T.M. Adamowicz 《Applied physics. B, Lasers and optics》2000,70(4):521-525
Single-mode operation at the Au-II 690-nm transition was obtained in a segmented hollow-cathode discharge laser without the
use of any additional frequency-selective device. The pressure of the helium buffer gas, which is responsible for the significant
homogeneous broadening of the laser line, was varied between 10 and 20 mbar. The discharge was excited with rectangular current
pulses (up to 3 A) six times exceeding the threshold value. The time dependence of the laser output during the 1-ms-long discharge
pulses is explained on the basis of the temperature and pressure changes in the tube. The highest small-signal gain at optimal
discharge conditions was 11%m−1.
Received: 1 July 1999 / Revised version: 4 November 1999 / Published online: 23 February 2000 相似文献
62.
Spectrophotometric determination of FeO in milligram samples of chrome spinels and related refractory minerals after high-frequency micro-fusion with lithium tetraborate in an inert atmosphere is described. Anomalous responses (apparent reduction or oxidation of FeO depending on the ferroïn-type reagent)_rendered the procedure highly unreliable. All the fluxes containing structural oxygen, as well as phosphoric acid, acted as oxidants even when atmospheric oxidation was rigorously excluded. However, the method is suitable for micro-determination of total iron in spinels. Spectrophotometric measurements gave an average relative standard deviation of 0.73%. 相似文献
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László B. Kiss János Kertész János Hajdu 《Zeitschrift für Physik B Condensed Matter》1990,81(2):299-303
We investigate the shape as well as the size- and temperature-dependence of the conductance noise spectrum of a small system containing electrons and both fixed and mobile scatterers. If the number of mobile scatterers within a phase-coherent region is sufficiently large, the temporal variation of the conductance can be viewed as a random walk process limited by the universal conductance fluctuations, resulting in a practically Lorentzian power spectrum. We discuss the conditions under which the noise spectrum of a system consisting of many phase-coherent regions is either Lorentzian or 1/f-like. The temperature-dependence of the power spectrum is determined by the hopping mechanism and the variation of the phase breaking length. As a function of temperature the spectrum satisfies power law scaling relations with exponents depending on the dimension and the temperature range; the spectral intensity can both increase and decrease with decreasing temperature. 相似文献
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The dynamics of an ensemble of identically prepared two-qubit systems is investigated which is subjected to the iteratively applied measurements and conditional selection of a typical entanglement purification protocol. The resulting dynamics exhibits strong sensitivity to initial conditions. For one class of initial states two types of islands characterize the asymptotic limit. They correspond to a separable and a fully entangled two-qubit state, respectively, and their boundaries form fractal-like structures. In the presence of incoherent noise an additional stable asymptotic cycle appears. 相似文献
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