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141.
I. V. Berezovskaya N. P. Efryushina A. S. Voloshinovskii G. B. Striganyuk P. V. Pir V. P. Dotsenko 《Journal of Applied Spectroscopy》2006,73(6):861-865
We have studied the luminescent properties of Eu2+/3+ and Yb2+ ions in strontium hexaborate SrB6O10 for excitation in the 120–400 nm region. The luminescence spectra of Ln2+ ions in SrB6O10 consist of overlapping bands in the 370–520 nm region, due to 5d → 4f transitions at several nonequivalent centers. In the
excitation spectra, besides the bands associated with 4f → 5d transitions in the Ln2+ ions, we also observe a band in the 135–160 nm region due to the transitions O(2p) → B(2s,2p) within the borate anions. The
luminescence of the Eu3+ ions is excited most efficiently in the region of the Eu3+ charge transfer band (λmax = 226 nm). The results obtained are compared with data for Ln in other strontium borates.
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 6, pp. 770–774, November–December, 2006. 相似文献
142.
《Nuclear Physics B》2006,744(3):330-339
In this paper we use the exact results for the anisotropic two-dimensional Ising model obtained by Bugrii and Lisovyy [A.I. Bugrii, O.O. Lisovyy, Theor. Math. Phys. 140 (2004) 987] to derive the expressions for dynamical correlation functions for the quantum Ising model in one dimension at high temperatures. 相似文献
143.
144.
《ournal of non Newtonian Fluid Mechanics》2005,125(1):61-70
This paper concerns the asymmetry in mean axial velocity distributions for the flow through an axisymmetric sudden expansion of a viscoelastic, shear-thinning aqueous solution of a polyacrylamide (PAA). The asymmetry manifests itself as an azimuthal variation in the length of the recirculation region of the separated flow downstream of the expansion inlet. For water, the flow is found to be axisymmetric. The asymmetry for the PAA flow, which remained unchanged despite alterations to the flow facility, is attributed to the high viscoelasticity of the polymer solution. The conclusion is drawn that the asymmetry is a purely physical feature of such a flow, and not the product of upstream or downstream flow conditions deriving from the flow facility, or the result of geometrical imperfections in the axisymmetric sudden expansion set-up. 相似文献
145.
Photoluminescence (PL) of anodic alumina membranes (AAMs) with ordered nanopore arrays fabricated in oxalic acid has been investigated under different annealing temperatures. The PL intensity firstly increases, and at 500 °C reaches a maximum value, then decreases. The structural transition from amorphous to γ-Al2O3 in AAMs has been confirmed by X-ray diffraction. Thermogravimetric analysis results and electron paramagnetic resonance measurements revealed that the PL band of alumina membranes could be attributed to the oxygen-related defect centers (F+ centers) rather than the luminescent centers transformed from oxalic impurities. 相似文献
146.
《Radiation Physics and Chemistry》2008,77(5):581-584
The cis-syn-cis isomer of dicyclohexano-18-crown-6 (DCH18C6) has been shown to be an efficient extractant able to perform the separation of Pu(IV) and U(VI) from fission products and then the separation of Pu(IV) from U(VI) without valence exchange as required in the PUREX process. This macrocycle was irradiated in nitric acid with a 137Cs γ source to study its radiation chemical stability. Radiation chemical yields (G) were determined by gas chromatography. The results show that the presence of uranyl nitrate has a strong influence on DCH18C6 radiation chemical stability. Indeed, the presence of this template ion increases the macrocycle stability by promoting fragments recombination. 相似文献
147.
148.
为了克服现有双丝型检测器无法进行水平、垂直两个方向同时测量同步光位置的缺点,合肥光源新研制了基于四象限光位置检测器的同步光位置测量系统,并使用对数比处理技术进行后续的数据处理。通过分别对光学成像系统和四象限光位置检测器的标定,最终得到基于四象限光位置检测器的光位置测量系统的性能参数为:水平方向灵敏度0.471 2 mm-1,线性范围为±1.83 mm,垂直方向灵敏度0.635 0 mm-1,线性范围±1.32 mm。与合肥光源现有的光位置测量系统相比,具有较高的性价比。 相似文献
149.
The dynamic structure factor S(q, ω) of a harmonically trapped Bose gas has been calculated well above the Bose-Einstein condensation temperature by treating
the gas cloud as a canonical ensemble of non-interacting classical particles. The static structure factor is found to vanish
s8 q
2 in the long-wavelength limit. We also incorporate a relaxation mechanism phenomenologically by including a stochastic friction
force to study S(q, ω). A significant temperature dependence of the density fluctuation spectra is found. The Debye-Waller factor has been calculated
for the trapped thermal cloud as a function of q and the number N of atoms. A substantial difference is found for small- and large-N clouds. 相似文献
150.
利用XRD、VUV及UV光谱等方法对Ce3+、Tb3+离子掺杂以及Ce3+、Tb3+离子共掺的3种BaCa2(BO3)2荧光粉的相纯度、发光性质、浓度猝灭现象进行研究。结果表明:3种荧光粉在VUV波段有较好的吸收,基质吸收带位于140~190 nm范围。Ce3+在BaCa2(BO3)2的最低4f5d跃迁带位置在360 nm附近,其5d→2FJ(J=5/2, 7/2)发射峰分别位于393,424 nm。Tb3+掺杂的样品在172 nm激发下的发射光谱由4个窄带组成,分别对应5D4→7FJ(J=3,4,5,6)的跃迁,其中占主导位置的是5D4→7F5的跃迁,大约位于543 nm处,主要为绿光发射。在Ce3+,Tb3+离子共掺杂的BaCa2(BO3)2光谱中,观察到Ce3+-Tb3+离子间有能量传递。 相似文献