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1.
A method for determining the content of a 4-epitetracycline impurity in tetracycline preparations from its optical activity
in methanol solutions, which contain sodium chloride, is developed.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 6, pp. 842–843, November–December, 1999. 相似文献
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The design characteristics of the optical cuvette suggested here provide the possibility of accomplishing the uniaxial orientation
of gels with retention of the constancy of their volume, which makes it possible to carry out highly accurate polarization
measurements with commercial spectropolarimeters in directions parallel and perpendicular to the axis of orientation. Using
as examples polyacrylamide gels containing biologically important molecules and membranes, the possibility of measuring absorption
spectra, the linear dichroism, and the dispersion of optical rotation is demonstrated.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 2, pp. 286–289, March–April, 1999. 相似文献
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J. Etxebarria C. Socías J. Herreros M. A. Arriandiaga J. Fernández 《Phase Transitions》2013,86(2-3):179-189
The optical dispersion of (C12H25NH3)2ZnCl4 and (C12H25NH3)2ZnCl4: Co is investigated by means of birefringence and optical absorption measurements in the temperature region around their isotropic points. The birefringence dispersion is analyzed in terms of a simple oscillator model based on the absorption band structure of both materials. A fairly good agreement is found between the thermal behaviour of the adjustable parameters of the oscillator model and the temperature dependence of the absorption spectra. The results suggest the existence of a structural phase transition at 315 K. 相似文献
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本文对光学玻璃的特殊色散机理进行了深入研究。研究认为,光学玻璃的特殊色散性能表征参数主要是相对部分色散偏离值ΔP_(g,F),ΔP_(g,F)绝对值越大,表明光学玻璃的特殊色散越大,越有利于消除光学系统的二级光谱。光学玻璃的特殊色散机理是由紫外和红外本征吸收引起。色散曲线中本征吸收峰的漂移和强弱将影响可见光区色散曲线斜率,进而使玻璃的相对部分色散偏离值变化。紫外本征吸收是由电子跃迁引起的;而红外本征吸收是由分子或分子集团振动造成的。开展特殊色散机理研究不仅可以深入揭示光学玻璃的"组分-结构-性能"关系规律,而且有助于开发特殊色散性能更优异的新型光学玻璃。 相似文献
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Segregation during crystal growth from melt under two conditions is studied by using crystal mass, which can be measured easily,
as an independent variable, and a method to determine the effective segregation coefficient and absorption cross section of
optical dopant is given. When the segregated solute disperses into the whole or just a part of melt homogenously, the concentration
C
s in solid interface will change by different formulas. If the crystal growth interface is conical and segregated solute disperses
into melt in total or part, the solute concentration at r = 2/3R, where r is the distance from the growth cross section center and R the crystal radius, is independent on the shape of the crystal growth interface, and its variation at r = 2/3R can be regarded as the result from crystal growth in flat interface. With C
s variation formula in solid and absorption cross section σ for optical dopant, the absorption coefficients along the crystal growth direction can be calculated, and the corresponding
experimental value can be obtained through the crystal optical absorption spectra. By minimizing the half sum, whose independent
variables are k, ΔW or σ, of the difference square between the calculated and experimental absorption coefficients from one or more absorption peaks
along the crystal growth direction, k and σ, or k and ΔW, can be determined at the same time through the Levenberg-Marquardt iteration method. Finally, the effective segregation
coefficient k, ΔW and absorption cross sections of Nd:GGG were determined, the results fitted by two formula gave more closed effective segregation
coefficient, and the value ΔW also indicates that the segregated dopant had nearly dispersed into the whole melt. Experimental results show that the method
to determine effective segregation coefficient k, ΔW and absorption cross sections σ is convenient and reliable, and the two segregation formulas can describe the segregation during the crystal growth from
melt relatively commendably.
Supported by the National Natural Science Foundation of China (Grant No. 50772112) 相似文献
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多次漫反射法测量粉末中的杂质吸收光谱及其计算机模拟 总被引:1,自引:0,他引:1
本文提出了用多次漫反射法来测定粉末样品的杂质吸收光谱,其结果与同材料的透明片状样品的杂质吸收光谱基本一致,为了验证更普遍的对不同折射率粉末情况,文中采用假设模型,以计算机模拟方法,其所得的结果说明,当颗粒足够小,色散又不太大时,所得的粉末样品与透明片状样品的吸收光谱一致,只差一个未知的吸收光程,如再与另一特性参数(寿命或量子效率)测量相结合,即可用来确定稀土杂质在材料中的辐射跃迁几率等物理参数。 相似文献
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Summary The paired-phonon analysis for boson mixtures is employed in conjunction with the hypernetted-chain approximation to study
the ground-state properties of an impurity embedded in liquid4He. Chemical potentials, volume coefficients and other thermodynamic quantities as well as some of the most interesting optimal
correlation functions are calculated for various impurities interacting with the4He background atoms via Lennard-Jones potentials of differing strength.
To speed up publication, the authors of this paper have agreed to not receive the proofs for correction. 相似文献
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S. A. Mikhnov 《Journal of Applied Spectroscopy》1999,66(6):994-998
It has been found that the F-band of optical absorption which is observed in ψ-irradiated NaF crystals consists of three overlapping
bands. The band at 345 nm of width 40 nm is independent of the impurity composition of the crystals; it disappears upon exposure
to radiation at 345 nm and appears again upon annealing at 460±15 K for 15 min. This band is correlatable in intensity with
the superfine structure of an EPR spectrum. The width (65–110 nm) and the spectral position (355–375 nm) of the second band
depend on the impurity composition of the crystal. The band of width 90–110 nm at 320–325 nm disappears upon annealing and
appears after exposure to light simultaneously with the disappearance of an EPR signal. It is established that the band at
345 nm is caused by quasimolecules based on fluorine atoms, that at 355–375 nm is triggered by F-centers with a different
impurity composition near the haloid vacancy, and the band at 320–325 nm owes its appearance to F-centers in a negatively
charged state (F′).
Institute of Molecular and Atomic Physics, National Academy of Sciences of Belarus, 70 F. Skorina Ave., Minsk, 220072, Belarus.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 6, pp. 849–853, November–December, 1999. 相似文献
16.
研究了掺稀土离子Pr^3 的碲铌铅玻璃的吸收光谱,色度色散和非线性光学性能。结果表明:高浓度的Pr^3 引入到碲铌铅玻璃系统后,仍能够形成均匀透明的玻璃,该玻璃具有高的折射率和非线性折射率。 相似文献
17.
V. T. Demarin L. V. Sklemina A. N. Tumanova E. I. Filatova 《Journal of Applied Spectroscopy》1997,64(6):854-857
We carried out a complex of investigations concerned with optimization of the conditions and reduction of the limits of atomic-emission
determination of impurities in high-purity selenium. We investigate the possibility that the types of impurities in the references
can affect the results of analysis.
Scientific-Research Institute of Chemistry at the Nizhnii Novgorod State University, 23/5, Gagarin Ave., N. Novgorod, 603600,
Russia. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 6, pp. 834–836, November–December, 1997. 相似文献
18.
The applicability of Kramers-Kronig (K-K) relation under nearly sharp resonant transition regime in narrow-gap semiconductors
has been established and consequently, a generalized dispersion relation for nonlinear optical susceptibility of a dielectric
is derived. This relation can be employed in the study of nonlinear optical processes in solids as well as in plasmas over
a wide frequency spectrum. 相似文献
19.
A full numerical calculation of the Franz--Keldysh effect on magnetoexcitons in a bulk semiconductor
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We have performed a full numerical calculation of the Franz--Keldysh (FK)
effect on magnetoexcitons in a bulk GaAs semiconductor. By employing an
initial value method in combination with the application of a perfect matched
layer, the numerical effort and storage size are dramatically reduced due to
a significant reduction in both computed domain and number of base
functions. In the absence of an electric field, the higher magnetoexcitonic
peaks show distinct Fano lineshape due to the degeneracy with continuum states
of the lower Landau levels. The magnetoexcitons that belong to the zeroth
Landau level remain in bound states and lead to Lorentzian lineshape, because they
are not degenerated with continuum states. In the presence of an electric
field, the FK effect on each magnetoexcitonic resonance can be identified for
high magnetic fields. However, for low magnetic fields, the FK oscillations
dominate the spectrum structure in the vicinity of the bandgap edge and the
magnetoexcitonic resonances dominate the spectrum structure of higher
energies.
In the moderate electric fields, the interplay of FK effect and
magnetoexcitonic resonance leads to a complex and rich structure in the
absorption spectrum. 相似文献
20.
A. N. Latyshev O. V. Ovchinnikov S. S. Okhotnikov 《Journal of Applied Spectroscopy》2003,70(6):817-820
A method for obtaining the spectra of atoms adsorbed on a single crystal with an ion-covalent bond is suggested. A photostimulated burst of luminescence is used to record the spectra. The atoms are deposited in a vacuum by a mass-spectrometric technique. The absorption spectrum of silver atoms adsorbed on a silver chloride single crystal at concentrations comprising a millionth fraction of the surface monolayer has been obtained. It has been revealed that the optical ionization potential of an adsorbed silver atom is equal to 1.9 eV. 相似文献