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961.
利用量子化学密度泛函理论B3LYP方法及 6 31G(d ,p)、6 311G(d ,p)、6 31+G(d ,p)和 6 311+G(d ,p)基组对五氟代吡啶、2 ,6 二氟代吡啶和 2 氟代吡啶分子的阳离子进行了计算研究 .B3LYP构型优化和频率分析计算结果表明这三种氟代吡啶阳离子的结构分别具有C2v、C2v和Cs 对称性 ,电子基态分别为2 A2 、2 A2 和2 A″ .对离子和分子的计算构型做了比较 .利用B3LYP方法和不同的基组对这三种阳离子及其分子进行了自然布居分析计算 .用B3LYP方法对这三种阳离子 (自由基 )中的超精细结构进行了计算 ,对五氟代吡啶、2 ,6 二氟代吡啶和2 氟代吡啶分子的垂直电离势和绝热电离势进行了计算 ,与实验值符合得很好 相似文献
962.
Lü Baida & PAN Liuzhan . Institute of Laser Physics Chemistry Sichuan University Chengdu China . Department of Physics Luoyang Normal College Luoyang China . State Key Laboratory of Laser Technology Huazhong University of Science Technology Wuhan China Correspondence should be addressed to L Baida 《中国科学G辑(英文版)》2004,47(1):24-35
Inrecentyearsanewbranchofmodernphysicalopticscalledsingularoptics[1]hasbeendeveloped.In2002theworkinsingularopticswasextendedfrommonochromaticlighttospatiallyfullycoherentandpolychromaticlightbyGburetal.[2—4].Itwasfoundthat,whenaconverging,spatiallyfullycoherentandpolychromaticsphericalwaveisdiffractedatanaperture,anomalousspectralchangestakeplaceclosetozerosoftheintensityinthefarfield;i.e.thespectrumisredshiftedatsomepoints,blueshiftedatothers,andsplitintotwolineselsewhere.Thepredictionsofsp… 相似文献
963.
Real-time visualisation of deformation fields using speckle interferometry and temporal phase unwrapping 总被引:1,自引:0,他引:1
A real-time system for analysing data from speckle interferometers, and speckle shearing interferometers, has been developed. Interferograms are continuously recorded by a digital camera at a rate of 60 frames s−1 with temporal phase shifting carried out at the same rate. The images are analysed using a pipeline image processor. With a standard 4-frame phase-shifting algorithm (phase steps of π/2), wrapped phase maps are calculated and displayed at 15 frames s−1. These are unwrapped using a temporal phase unwrapping algorithm to provide a real-time colour-coded display of the relevant displacement component. Each camera pixel (or cluster of pixels) behaves in effect as an independent displacement sensor. The reference speckle interferogram is updated automatically at regular user-defined intervals, allowing arbitrarily large deformations to be measured and errors due to speckle decorrelation to be minimised. The system has been applied to the problem of detecting sub-surface delamination cracks in carbon fibre composite panels. 相似文献
964.
Y. D. Kolekar S. B. Kulkarni Keka Chakraborty A. Das S. K. Paranjpe P. B. Joshi 《Pramana》2004,63(2):189-197
Nd2Sn2O7 pyrochlores with the substitution of Zr4+ were prepared by conventional ceramic double sintering technique. The single-phase formation was confirmed by X-ray diffraction
and neutron diffraction techniques. Relative intensity calculations for X-ray diffraction analysis were performed for oxygen
positional parametersx = 0.331 and 0.375, while Rietveld refinements were employed for neutron diffraction data. The neutron diffraction study revealed
that there are only two anion sites with 48f and 8b positions. This indicates that the 8a site, i.e. O(3) sublattice, is completely
vacant and the structure is a perfect cubic pyrochlore with space group Fd3m (O
h
7
). From the conductivity measurements, it is observed that the electronic conductivity dominates from room temperature up
to about 525 K and forT > 525 K, the oxygen ion conduction dominates the charge transport in these compositions. Complex impedance spectroscopy indicates
the existence of grain and grain boundary as two separate elements. 相似文献
965.
ZHANG Han-hui LIN Zheng-zhong HUANG Chang-cang SUN Rui-qing WU Xiao-yuan LIN Zhi-hua 《光谱学与光谱分析》2004,(5)
用FTIR ,NIRFT Raman ,UV VisDRS和荧光光谱等对五个新型具有 [(PO4) 4 MoⅤ6O15]12 -阴离子簇的化合物 :Na·(H4TETA) 3 ·(H3 O) 5·{Zn[(HPO4) 2 (PO4) 2 Mo6O15]2 } (2 ) ,(H2 en) 7·(H3 O) 4 ·{Cu[(HPO4) 2(PO4) 2 Mo6O15]2 }·H2 O (3) ,(H3 DETA) 2 ·(H3 O) 3 ·{Co0 5[(HPO4) 2 (PO4) 2 Mo6O15]}·H2 O (4) ,[Co(H3 TETA) ]2 {Co0 5[(HPO4) (PO4) 3 Mo6O15]}· 3 5H2 O (5 )和 (H3 DETA)· (H3 O ) 4 · {Co1 5[(HPO4) 2(PO4) 2 Mo6O15]}·0 5H2 O (6 ) ,进行研究 ,并探讨其结构和性能的关系。这些化合物具有 {M [(PO4) 4 Mo6O15]2 }二聚体单元 ,化合物 2~ 4的二聚体间通过与有机分子和水分子的氢键形成三维网状结构 ;化合物 5和 6的 {Co[(PO4) 4 Mo6O15]2 }二聚体间是分别通过 [CoH3 TEATA]基团和CoO4四面体组成网状结构。磷钼酸盐的特征振动频率和这些化合物的结构相关 ;化合物的三个UV VisDRS特征谱带分别属于Od→Mo,Oμ→Mo和O→M电荷转移 ;观察到以 2 4 0nm激发 ,在 4 10nm附近出现的由Oμ→Mo跃迁激发引起的较强的荧光发射谱带。 相似文献
966.
The high resolution infrared spectra of monoisotopic F35Cl18O3 and F37Cl18O3 have been studied in the region of the ν4 fundamentals, centered at 1278.3 and 1263.3 cm−1, respectively. Large perturbations are observed in both bands due to a Fermi type anharmonic resonance with the ν2 + ν5 combination bands, centered at 1270.7 cm−1 in F35Cl18O3 and 1257.3 cm−1 in F37Cl18O3. In particular, they affect the kl > 0 levels of the v4 = 1 and v2 = v5 = 1 states which cross at kl ? 18 in F35Cl18O3 and kl ? 3 in F37Cl18O3, due to the opposite values of and . The Δl = Δk = ±2 and Δl = 0, Δk = ±3 essential resonances are also effective in the excited states of the dyad in F35Cl18O3, while in F37Cl18O3 only the Δl = Δk = ±2 one is active. In the spectrum of F35Cl18O3 3423 transitions have been assigned, 10% of them belonging to ν2 + ν5. The rovibrational parameters and the interaction constants between the v4 = 1 and v2 = v5 = 1 levels have been obtained. The depertubed band origins of ν4 and ν2 + ν5 are 1277.310567(165) and 1271.753733(195) cm−1, respectively, and the anharmonic resonance constant is 2.804416(153) cm−1. For F37Cl18O3, 3022 transitions have been assigned, 38% belonging to the ν2 + ν5 combination band. The depertubed band origins are 1260.856338(123) and 1259.872338(134) cm−1, for ν4and ν2 + ν5 and the constant is 2.9350669(405) cm−1. The equilibrium geometry of perchloryl fluoride, re (ClO) = 139.7(3) pm, re (ClF) = 161.0(5) pm, and αe (OClO) = 115.7(4) degree, has been determined using the Ae and Be equilibrium constants of the four symmetric isotopologues of perchloryl fluoride, F35/37Cl16O3 and F35/37Cl18O3. 相似文献
967.
Tomographic analysis of the central magnetohydrodynamic oscillations on the HT-7 tokamak 总被引:1,自引:0,他引:1 下载免费PDF全文
Multi-channel soft x-ray (SX) detectors are applied to generate images of
magnetohydrodynamic (MHD) oscillation on the HT-7 tokamak, and the data
from SX cameras are analysed by using the
Fourier--Bessel harmonic reconstruction method and the singular value
decomposition. The image
reconstruction of SX emissivity is obtained on the assumption of plasma
rigid rotation. One of the important phenomena in the HT-7 discharge is the
transition from the sawtooth oscillations to the MHD oscillations when the
plasma density grows higher. The MHD structure
observed in the SX tomography is featured as follows: the magnetic surface of MHD
structure is made up of the crescent-shaped ``hot core' and the circular
``cold bubble'. The structure of the magnetic surface is relatively stable.
It rotates in the direction of the electron diamagnetic drift at a
frequency being the oscillation frequency of the MHD oscillations. 相似文献
968.
Effects of initial frequency chirp on the linear propagation characteristics of the exponential optical pulse 总被引:6,自引:0,他引:6 下载免费PDF全文
In this paper, the linear propagation characteristics of the exponential optical
pulse with initial linear and nonlinear frequency chirp are numerically studied in a
single mode fibre for \be2<0. It can be found that the temporal full width at
half maximum and time-bandwidth product of exponential pulse monotonically increase
with the increase of propagation distance and decrease with the increase of linear
chirp C for C<0.5, go through an initial decreasing stage near \zeta=1, then
increase with the increase of propagation distance and linear chirp C for
C\geq0.5. The broadening of pulses with negative chirp is faster than that with
positive chirp. The exponential pulse with linear chirp gradually evolves into a
near-Gaussian pulse. The effect of nonlinear chirp on waveform of the pulse is much
greater than that of linear chirp. The temporal waveform breaking of exponential
pulse with nonlinear chirp is first observed in linear propagation. Furthermore, the
expressions of the spectral width and time-bandwidth product of the exponential
optical pulse with the frequency chirp are given by use of the numerical analysis
method. 相似文献
969.
970.