尿素分子红外光谱与晶体红外吸收截止波长的量子化学研究

应用量子化学从头算方法准确计算了尿素分子的红外光谱,得到分子的振动频率和红外振动强度与实验值相符。在分子红外光谱计算的结果基础上估算了尿素晶体的红外吸收截止波长,其值为１．４０μｍ,与测量的符合得很好。对光学晶体红外透过窗口的研究具有重要意义。     

Theoretical interpretation of spectral signs of an oxymethyl group in the IR spectrum of methyl-β-D-glucopyranoside

For the first time, we have assigned the observed absorption bands and interpreted the IR spectrum of methyl-β-D-glucopyranoside in detail in the 1500–800 cm⁻¹ region, based on a full calculation of the frequencies and absolute intensities of the normal vibrations of the molecule and their comparison with the experimental data. We have identified two groups of spectral signs indicating an oxymethyl substituent has replaced the hydroxyl group on the C₍₁₎ atom in the glucopyranoside: absorption bands of medium intensity due to the characteristic vibrations of the substituent, and intense bands due to an unusual “interaction” between many structural moieties. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 6, pp. 721–727, November–December, 2006.     

神东煤镜质组结构模型红外光谱的量子化学计算

为了煤的洁净、高效和高附加值利用,需要从分子水平上了解煤的结构。在文献[5]中,作者以元素分析和13C核磁共振为依据构建了神东煤镜质组(SV)的结构模型,所建模型的13CNMR模拟计算结果能很好的和实验结果比对,为了进一步验证该模型的准确性,以半经验量子化学计算方法VAMP对SV模型结构的红外谱进行了计算。结果显示模拟计算得到的红外谱图与实验谱图相比峰形相似,但整个计算谱明显偏向高波数区域。经过对相关模型化合物的红外谱进行计算,其原因是半经验方法计算所得官能团结构的振动频率均高于实验测试结果。依此对SV结构模型的红外模拟谱进行修正,修正后实验和模拟谱图能很好地吻合,这进一步证实SV结构模型可以真实的反映神东煤镜质组的结构组成特点。     

Unitary cocycle representations of the Galilean line group: Quantum mechanical principle of equivalence

We present a formalism of Galilean quantum mechanics in non-inertial reference frames and discuss its implications for the equivalence principle. This extension of quantum mechanics rests on the Galilean line group, the semidirect product of the real line and the group of analytic functions from the real line to the Euclidean group in three dimensions. This group provides transformations between all inertial and non-inertial reference frames and contains the Galilei group as a subgroup. We construct a certain class of unitary representations of the Galilean line group and show that these representations determine the structure of quantum mechanics in non-inertial reference frames. Our representations of the Galilean line group contain the usual unitary projective representations of the Galilei group, but have a more intricate cocycle structure. The transformation formula for the Hamiltonian under the Galilean line group shows that in a non-inertial reference frame it acquires a fictitious potential energy term that is proportional to the inertial mass, suggesting the equivalence of inertial mass and gravitational mass in quantum mechanics.     

Reflectivity of strongly doped n-Bi2Te3 crystals in the IR region

Czechoslovak Journal of Physics - Reflectivity has been measured in the region of plasma resonance frequency on strongly doped n-Bi2Te3(I) crystals with a free electron concentration of 2×10...     

Optical properties of magnetic quasi-2D nanocomposites in the IR spectral region

The optical absorption spectra of magnetic quasi-2D Co island films and of hybrid Co/SiO₂ multilayers in which island films are separated by SiO₂ layers were studied. It was found that, when the Co film was masked by a thin SiO₂ layer, the absorption considerably increased and exceeded 0.8. This was observed when the Co fraction was substantially lower than its critical value for the percolation transition. Moreover, the maximal absorption in this case weakly depends on both the effective film thickness and the number of Co layers. Numerical analysis shows that the observed peculiarities of the absorption spectra of the structures based on quasi-2D granulated Co films are connected to a great extent with the peculiar features of the interference effects occurring in such systems.     

Spectrum of Exciton in a Quantum Wire

In the present work we obtain the wave function and the corresponding energy of exciton confined within a quantum wire. What we do is to obtain the approximate analytical solution of the corresponding Schrödinger equation for the quantum wire in the presence of Coulomb and confining terms. We then calculate the energy and the binding energy of the exciton. By using the obtained energy of exciton, we calculate the corresponding wave length. The comparison of the obtained wave length with the emitted wave length from the semiconductor under study shows a good agreement with experimental results.     

Ring-puckering combination band spectra of 1,3-disilacyclobutane in the SiH2 stretching region

Three sets of sum bands and two sets of difference bands arising from the combination of the ring-puckering vibration with SiH₂ stretching modes have been observed between 2060 and 2260 cm^?1 in the infrared spectrum of 1,3-disilacyclobutane. An unusual feature of the spectrum is that there is little correlation in intensity between corresponding sum and difference bands. An additional sum band and a difference band were also observed in the Raman spectrum. The spectra confirm the low-frequency ring-puckering assignment and verify the position of the weak 2–3 transition near 31 cm^?1. The puckering levels in the excited states of the SiH₂ stretching modes are virtually unshifted relative to the ground state demonstrating that negligible coupling exists between these vibrations. In addition, sum and combination bands have been observed off an SiD₂ stretching mode for 1,3-disilacyclobutane-1,1,3,3-d₄.     

Quantum group symmetries and non-local currents in 2D QFT

We construct and study the implications of some new non-local conserved currents that exist is a wide variety of massive integrable quantum field theories in 2 dimensions, including the sine-Gordon theory and its generalization to affine Toda theory. These non-local currents provide a non-perturbative formulation of the theories. The symmetry algebras correspond to the quantum affine Kac-Moody algebras. TheS-matrices are completely characterized by these symmetries. FormalS-matrices for the imaginary-coupling affine Toda theories are thereby derived. The application of theseS-matrices to perturbed coset conformal field theory is studied. Non-local charges generating the finite dimensional Quantum Group in the Liouville theory are briefly presented. The formalism based on non-local charges we describe provides an algernative to the quantum inverse scattering method for solving integrable quantum field theories in 2d.     

Optical constants of industrial polymers in the IR region

The process of resonant photoluminescence of semiconductor quantum dots, which may serve as a basis for efficiently studying the dynamics of their electronic subsystem, is described theoretically. Potentialities of the spectroscopy of this type are analyzed using, as an example, the intraband relaxation of charge carriers in a quantum dot caused by their interaction with plasmons of doped regions of the heterostructure. Analytical expressions are obtained for the photoluminescence intensity, and conditions are found under which its spectrum provides the most explicit information about the intraband relaxation rates.     

蒽醌染料紫外光谱的量子化学CNDO/2研究

茵醌染料在纺织工业中占有重要的位置。将蒽醌环上引入不同的基团则成为不同的染料。应用量子化学CNDO／2方法对蒽醌染料的紫外光谱进行研究,算出了各分子轨道的能量及相应紫外光谱吸收峰的位置。发现引入的助色基其能量差、紫外光谱最大吸收峰及红移呈规律变化,原因均为n-n^*轨道跃迁。     

He-CO散射截面的量子力学研究

采用精确度较高的密耦方法(Close-Coupling)计算了He-CO碰撞的散射截面,能量从5meV～70meV,计算结果与M.Keil等的实验结果(64meV)基本相符,研究表明:势能的零点能位置、势阱深度、势阱位置、排斥势强度以及势能在势阱附近的方向性都对散射截面有较大的影响.     

用量子力学方法计算H+H2碰撞的反应几率

利用量子力学耦合通道扭曲波近似法(CCDWA)和三种势能面计算了H+H2碰撞的反应几率,结果发现在相同的势能面下利用CCDWA方法计算的反应几率和公认较好的计算结果符合很好,不同势能面共线势垒高度的差别将引起反应几率的不同.