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991.
The transmitted photon spectra of133Ba,22Na,137Cs,54Mn and60Co point sources are measured through different thicknesses of water, concrete and sand. The multiple-scatter peaks observed
in these materials at 60, 90 and 100 keV energies respectively are found to be independent of incident photon energy and thickness
of the medium. 相似文献
992.
BaFClxBr1-x:Sm2+中5D2→7F0跃迁几率及其对烧孔效率的影响 总被引:1,自引:0,他引:1
本文以BaFClxBr1-x:Sm2+中5D2→7F0的跃迁几率随x变化为中心对BaFClxBr1-x:Sm2+体系4f5d带的激发光谱、5D2→7F0跃迁的荧光衰减随温度的变化特性、5D2→7F0的跃迁几率等进行了研究。从而得出结论:在BaFClxBr1-x:Sm2+中,随Br含量的增大,4f5d带与5D2能级更加接近,使7F0→5D2的吸收截面增大,从而可能提高在5D2:能级烧孔的效率。 相似文献
993.
The optical absorption spectrum of Ni2+ ion doped in ammonium zinc sulphate has been studied at room and liquid air temperatures. From the nature and the positions
of the bands a successful interpretation of all the bands could be made assumingO
h
symmetry for the Ni2+ ion in the crystal. The fine splitting of the3
T
1
1 band at liquid air temperature has been successfully interpreted to be due to spin-orbit interaction. The crystal field and
spin-orbit parameters derived areDq=1000 cm−1;B=750 cm−1;C=3.45B andξ=600 cm−1. 相似文献
994.
Joseph P. Sattler George J. Simonis 《International Journal of Infrared and Millimeter Waves》1984,5(4):465-473
We report the refractive indices and absorption coefficients for four beryllia (BeO) ceramic samples. These dielectric properties have been measured over the range from 4 to 18 cm–1 by use of a Michelson interferometer. The index n, follows the linear relationship n=0.6517 cm3/g×+0.7130 with density, , over the range 2.8<<3.0 g/cm3. 相似文献
995.
996.
宋敏 《光谱学与光谱分析》1993,13(3):11-14,62
我们用HRD-1型双光栅单色仪记录了碘分子在可见光区域的吸收光谱。确定了大量的带头,由此得出了碘分子的离解限、离解能、力常数和振动基频。实验结果与理论结果很符合。 相似文献
997.
M. Karny L. Batist B. A. Brown D. Cano-Ott R. Collatz A. Gadea R. Grzywacz A. Guglielmetti M. Hellstrm Z. Hu Z. Janas R. Kirchner F. Moroz A. Piechaczek A. P
ochocki E. Roeckl B. Rubio K. Rykaczewski M. Shibata J. Szerypo J. L. Tain V. Wittmann A. Whr 《Nuclear Physics A》2001,690(4):45
The Gamow–Teller β decays of the neutron-deficient indium isotopes 104–107In have been investigated by using total absorption γ-ray spectrometry on mass-separated sources. The experimental Gamow–Teller strength, deduced as a function of the excitation energy in the daughter nuclei 104–107Cd, is compared to shell-model predictions. 相似文献
998.
A.G. Kofman 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,17(2):153-165
The electromagnetically induced transparency (EIT) with a (near-)resonant chaotic (amplitude-phase fluctuating, Gaussian-Markovian)
coupling field is studied theoretically. The Fourier transform of the steady-state EIT spectrum, which determines a nonstationary
probe absorption, is also considered. This quantity equals the average diagonal element of the (reduced) evolution operator
of the coupled transition (the evolution function). The exact solution in the form of a continued fraction is obtained and
used to perform numerical calculations. Moreover, a number of approximate analytical results are obtained, which, together
with the results of previous publications, describe the EIT and the evolution function in all possible regimes. In particular,
in the constructive-interference case the EIT increases with the coupling-field bandwidth ν at sufficiently small ν. For a strong field, the maximum of the transparency as a function
of ν is less than that for a monochromatic field of the same average intensity. In contrast, for a weak field, there is a
range of ν values, where the field fluctuations do not affect the EIT. The latter result is shown to hold for a broad class of stochastic fields.
Received 31 December 2000 and Received in final form 14 May 2001 相似文献
999.
In this paper, an ultra-wideband Janus metastructure (MS) utilizing anapole mode for detector in the terahertz (THz) range by graphene is proposed. Specifically, when Fermi level (Ef) is set to 0.9 eV, the MS demonstrates ultra-broadband absorption exceeding 0.9 from 0.754 to 5 THz in the −z-direction with a relative bandwidth of 147.6 %, in which perfect absorption of over 98% develops from 3.24 to 5 THz. In the case of the +z-direction, the absorptivity maintains around 0.6 within the 0.745 ∼ 5 THz range. As Ef equals 0 eV, the difference in absorption between the −z-direction and +z-direction exceeds 0.9 from 4.49 to 4.76 THz. The study also explores the MS for refractive index sensing near 3.71 THz by a unique difference detection, measuring two refractive index ranges: 1.2 ∼ 2.6 and 4.5 ∼ 4.7, with corresponding sensitivities of 0.0450 and 0.0304, respectively. Owing to its highly symmetrical structure, the MS is insensitive to the polarization state of the electromagnetic (EM) waves, performing remarkable angular stability as the incident angle varies from 0 to 60 degrees in the −z-direction. These splendid properties make the design a good candidate for biomedical sensing, EM cloaking, and full-space EM wave control. 相似文献
1000.
The regime of atomization of Si in the presence of Fe-subgroup metals was investigated with the use of a “Saturn” spectrophotometer
and a “Graphit-2” electrothermic atomizer. The optimal operating parameters of the atomizer have been determined. It was established
that the optimal value of the ashing and the atomization temperatures are, respectively, 900–1000°C and 2400°C, the optimal
rate of temperature rise at the stage of atomization is 1400 K/sec, and the appropriate amount of Fe, Co and Ni additions
is 1–2 μg. It was established that the formation of gaseous silicides of the Fe-subgroup metals, the dissociation energies
of which are lower than the dissociation energies of Si oxides and carbides, increases the sensitivity for determination of
Si.
To whom correspondences should be addressed.
Institute of Single Crystals, National Academy of Sciences of Ukraine, 60, Lenin Ave., Khar'kov, 310001, Ukraine. Translated
from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 2, pp. 153–157, March–April, 1999. 相似文献