共查询到20条相似文献,搜索用时 15 毫秒
1.
Jaw-Luen Tang Chen-Wei Chen Jiunn-Yuan Lin Chia-Chen Hsu Tzer-Hsiang Huang 《Optics Communications》2006,266(2):669-675
Transient optical Kerr effect of liquids C2H4Cl2 and C2H4Br2 is investigated, for the first time to our knowledge, with a femtosecond (fs) probe laser delayed with respect to a coherent fs pump laser. Coherent coupling and electronic Kerr signals are observed around zero delay when pump and probe overlap. Persisting after the pump-probe overlap are Kerr signals arising from the torsional and other intramolecular vibrations of the trans and gauche conformations; Kerr signals arising from the intermolecular motion are also observed. Vibrational quantum interference is only observed in liquid C2H4Br2 and the related beats data are fitted with the torsional vibrations, 91 cm−1 (gauche) and 132 cm−1 (trans), and the CCBr angle-bending vibrations, 231 cm−1 (gauche) and 190 cm−1 (trans), with dephasing times, 0.45 ps, 0.45 ps, 2 ps, and 1.5 ps, respectively. These vibrational frequencies agree with those obtained in the frequency-domain. That no vibrational mode is observed for C2H4Cl2 might be attributed to ineffective Raman-pumping. Kerr signals observed after the pump-probe overlap are Fourier transformed to give the spectra of the intermolecular motion and the vibrational spectrum, which agrees with the one observed in the infrared absorption and/or Raman scattering heretofore. 相似文献
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3.
The Raman line shapes of the ν1(A 1)C-H and C-D stretching fundamentals in liquid CHCl3 and CDCl3 have been measured as a function of pressure from 1 bar to 4·5 kbar within the temperature range 30°C to 90°C. Densities have also been determined under the same experimental conditions. The vibrational relaxation rates are obtained from the isotropic component of the Raman band and the experimental results can be summarized as follows: (i) as T increases at constant density the vibrational relaxation rate increases; (ii) at constant T, the increase in density produces an increase in the relaxation rate; (iii) an increase in temperature at constant pressure results in an increased relaxation rate. The above three cases hold for the CDCl3 liquid, whereas only (ii) may be stated for the CHCl3 liquid. The experimental vibrational data are interpreted in terms of the Kubo stochastic line-shape theory and the collinear-isolated-binary-collision model proposed by Fischer and Laubereau. Application of the Kubo formalism shows that vibrational dephasing is the dominant relaxation mechanism and that the modulation is fast both in liquid CHCl3 and CDCl3. Interpretation in terms of the binary collision dephasing model leads to the following results: (i) the pure dephasing mechanism seems to be the dominant broadening mechanism for the isotropic Raman line shapes studied; (ii) the calculated dephasing rates as a function of density and temperature show agreement with the experimental data. In these calculations the elastic collision times are obtained from the modified Enskog theory. 相似文献
4.
Three-dimensional ab initio dipole moment surfaces and stretching vibrational band intensities of the XH3 molecules 总被引:1,自引:0,他引:1
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Stretching vibrational band intensities of XH3 (X=N, Sb) molecules are investigated employing three-dimensional dipole moment surfaces combined with the local mode Hamiltonian model.The dipole moment surfaces of NH3 and SbH3 are calculated with the density functional theory and at the correlated MP2 level,respectively. The calculated band intensities are in good agreement with the available experimental data. The contribution to the band intensities from the different terms in the polynomial expansion of the dipole moments of four group V hydrides (NH3, PH3,AsH3 and SbH3) are discussed. It is concluded that the breakdown of the bond dipole approximation must be considered. The intensity “borrowing” effect due to the wave function mixing among the stretching vibrational states is found to be less significant for the molecules that reach the local mode limit. 相似文献
5.
V. G. Nikiforov A. G. Shmelev G. M. Safiullin V. S. Lobkov V. V. Samartsev 《Bulletin of the Russian Academy of Sciences: Physics》2012,76(3):295-298
Optical control of coherent intramolecular oscillations in chloroform CHCl3 and dimethyl sulfoxide (CH3)2SO is attained experimentally under normal conditions by means of femtosecond polarization spectroscopy. Nonresonant excitation
of the medium is accomplished by a sequence of two linearly polarized laser pulses. The state of the medium is probed by the
third pulse via the optical Kerr effect. We show that control over the vibrational dynamics of molecules on a sub-picosecond
scale can be achieved by varying the delay between the excitation pulses and their relative intensity. 相似文献
6.
A. V. Telegin Yu. P. Sukhorukov A. P. Nosov V. A. Bessonova E. A. Gan’shina 《Physics of the Solid State》2017,59(2):292-297
Results of studies of magnetooptical Kerr effect and magnetoreflection of natural light in La2/3Ba1/3MnO3/SrTiO3 films of different thickness are presented. The Kerr effect was shown to be the most prominent in visible and near IR range; magnetoreflection was found to achieve its maximum of about 10% in the mid-IR range near the room temperature. Physical mechanisms defining the value and sign of the effects and the influence of the thin-film state on the magnetooptical properties are discussed. Magnetoreflection is estimated in the framework of the magnetorefractive effect theory. 相似文献
7.
基于各向异性的平面电磁波传输理论和4×4矩阵法,计算了MnBi,Mn0.53Bi0.47,Mn0.52Bi0.44Sb0.04磁性多层膜系列的磁光科尔旋转角、椭圆率随波长、入射角、磁性层厚度变化曲线.计算结果表明,模拟的科尔旋转角、椭圆率随波长变化规律与实验结果吻合很好;在一定波长的垂直入射下,模拟的科尔旋转角、椭圆率随磁性层厚度变化曲线出现科尔谱极大;在磁性层厚度一定的情况下,当入射光以某一角度
关键词:
4×4矩阵法
磁性多层膜
磁光科尔谱
介电张量 相似文献
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A full dimensional calculation of the vibrational eigenstates and spectrum of CHF3, using Van Vleck perturbation theory followed by a variational calculation, is presented. For this, a Taylor series expansion of the potential which includes important terms up to sixth order is obtained. The importance of the quintic and sextic terms is established by comparison of states obtained with and without these terms. Adjusting the potential slightly for better agreement with experiments, we have computed all the eigenstates below 6500cm?1. These states are used with an ab initio dipole moment surface to calculate transition intensities from the ground state. The calculated results agree well with experimental findings. 相似文献
10.
Toshiko Katō 《Molecular physics》2013,111(3):559-564
A theoretical model of vibrational dephasing of Raman active ions in aqueous electrolyte solutions is presented in which a probe ion is coupled to the bath by direct ion-solvent and ion-ion interactions. Expression for the vibrational width in terms of concentrations and efficiencies of the vibrational frequency modulation by ion-perturber interactions is given in the fast modulation scheme. The observed linear concentration dependence of the vibrational dephasing width of the v 1(A'1) mode of NO3 - in aqueous solutions is reasonably well explained from this model, and efficiencies of the dephasing paths through NO3 --water hydrogen bonding interaction and contact NO3 --cation pair formation interaction are estimated. Anions in the solution give only a secondary effect to nitrate vibrational dephasing because of interionic repulsive forces. 相似文献
11.
Per Jensen 《Molecular physics》2013,111(17):1253-1285
12.
用真空电子束蒸发制备了MnBixAl0.15薄膜.当0.4≤x≤0.7时,MnBixAl0.15薄膜的Kerr角与MnBix薄膜相比有显著增大;而当x>0.7时,MnBixAl0.15的Kerr角则比MnBix的要不,633nm波长测量时,MnBi0.5Al0.15的Kerr角为2.75°,而相对应的MnBi0.5薄膜只有1.56°.MnBi05Al0.15薄膜的室温饱和磁化强度Ms为3×105A/m,比MnBi0.5薄膜的Ms(4×105A/m)要小.推测当0.4≤x≤0.7时,Al可能部分占据Bi空位和部分取代Mn位,由于晶格收缩使得Mn 3d电子与Bi 6p电子的杂化概率增大,从而导致其Kerr效应增强.
关键词: 相似文献
13.
Ljup?o Pejov Vladimir M Petruševski 《Journal of Physics and Chemistry of Solids》2003,64(8):1353-1363
Fourier transform IR and Raman spectra of chromate anions isomorphously isolated in potassium, rubidium and cesium sulfate matrices were recorded at room and low temperature (∼100 K). On the basis of the detected second-order vibrational transitions involving the dopant species ν3 mode components, anharmonicity constants and harmonic eigenvalues for these modes were calculated. Despite the fact that, rigorously speaking, the appearance of the spectra of dopant chromate anions may be explained in terms of a Cs site symmetry, the ν3 stretching region resembles an approximate (A1⊕E) splitting (characteristic for a local C3v symmetry). Although such findings may be rationalized in terms of the latent symmetry concept, we propose an alternative explanation, based on the concept of vibrational mode mixing (a ‘Fermi-like’ resonance) of the CrO42−ν1 mode with the ν3a site-group component. We also derive a quantitative model based on the degenerate case stationary perturbation theory that allows an estimation of the relative importance of the latent symmetry versus vibrational mode mixing effects. In the present case, we show that the Fermi-like resonance is predominantly responsible for the observed spectral features. 相似文献
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Expressions are derived for the second and third Kerr virial coefficients, B K and C K, of spherical top molecules in terms of irreducible cluster polarizabilities, and values are calculated using the dipole-induced dipole model for argon, krypton, xenon, methane, tetrafluoromethane, neopentane and sulphur hexafluoride. For mixtures of rare gases it is shown that the collision-induced dipole moment makes a negligible contribution to B K. The effect of the choice of intermolecular potential function on the calculated second Kerr virial coefficients is also demonstrated. It is found that the predominant contributions to C K arise from the pair polarizability, and that the triplet polarizability is only of minor importance. 相似文献
16.
High order Correlation polarization potential for vibrational excitation scattering of diatomic molecules by low-energy electrons
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This paper introduces a correlation--polarization potential
with high order terms for vibrational excitation in
electron--molecule
scattering. The new polarization potential generalizes the two-term
approximation so that it can better reflect the dependence of
correlation and polarization effects on the position coordinate of
the scattering electron. It applies the new potential on the
vibrational excitation scattering from N2 in an energy range
which
includes the 2Пg shape resonance. The good agreement of
theoretical resonant peaks with experiments shows that polarization
potentials with high order terms are important and should be
included in vibrational excitation scattering. 相似文献
17.
Peter J. Meschter James W. Wright Charlie R. Brooks Thomas G. Kollie 《Journal of Physics and Chemistry of Solids》1981,42(9):861-871
Heat capacity data for solid nickel have been re-evaluated and analyzed into physical contributions, 0–1726 K. Two new sets of measurements of Cp(Ni), 333–1500 K, have been combined with literature data to produce an evaluated data set with uncertainty ? ± 2%. These smoothed data have been analyzed into vibrational harmonic, electronic, magnetic and dilatational contributions with the aid of auxiliary measurements of expansion coefficient, compressibility, vibrational and electronic densities of states, elastic constants, and magnetic exchange integral and susceptibility obtained from the literature. The vibrational harmonic term is interpreted in terms of a θD-vs-T curve in accord with predictions of the density-of-states distribution. The electronic contribution is smaller than predicted by free-electron theory due to a large electron-phonon effect. The electronic term for paramagnetic nickel is in good agreement with that predicted from band calculations. The magnetic contribution yields a magnetic entropy in accord with theoretical predictions, and a magnetic internal energy and critical-point behavior in agreement with the isotropic Heisenberg model. The experimental heat capacity can be accounted for without reference to vibrational anharmonic and vacancy contributions, in accord with recent calculations. 相似文献
18.
《Journal of Molecular Spectroscopy》1987,126(2):356-369
A comprehensive model for predicting rotational frequency components in various v10 vibrational levels of propyne was developed. A number of components of the rotational spectra in the ground and v10 = 1, 2, 3, 4 excited vibrational states of propyne in the frequency range 17–70 GHz have been obtained. Molecular constants for these vibrationally excited states have been determined from more than 100 observed rotational transitions. From these experimentally observed components and a model based upon first principals for C3v molecules, rotational constants have been expressed in a form which enables one to predict rotational components for vibrational levels for propyne up to v10 = 5. The model also appears to be useful in predicting rotational components in more highly excited vibrational levels but data were not available for comparison with the theory. Experimentally measured frequencies are presented and compared with those calculated using the results of basic perturbation theory. 相似文献
19.
我们测量了分子式为{Bi3-2xCa2x}[Fc2-yIny](Fe(3x)Vx)O12的铁石榴石单晶(简记为代In的BCVIG)在0.45—0.80μm内的饱和极向磁光克尔旋转谱。在0.47μm附近观察到一个强的旋转峰值。通过改变In,V(Bi)的替代量获得了室温下磁矩抵消点附近0.47μm磁光旋转值与成份的关系。发现当替代量的变化通过磁矩抵消点时,克尔旋转的符号突然由正变负,但其绝对值并不依替代量趋近磁矩抵消点(总4πMs下降)而逐渐下降。还发现In的代入使磁光旋转有所增强,在y≈0.15时增强最大。借助总磁光旋转为Bi增强了的次点阵磁光旋转迭加的模型解释了代In引起的旋转增强。按此拟合实验结果导出了0.47μm下四、八面体次晶格旋转系数之比为α4/α8≈1.5即单位Fe3+在四面体比在八面体对磁光旋转的贡献大。实验结果还表明,在x<1.0的配方区,并有小量In代入(y<0.15)时可望得到大磁光旋转材料。考虑到低而可变的4πMs,高的居里点和相当大的磁光旋转,该配方区的代In的BCVIG在磁光各种应用中将是强有力的竞争者。
关键词: 相似文献
20.
《Surface science》1986,169(1):153-175
Photoelectron spectra of diatomic molecules such as CO and N2 weakly chemisorbed on metal surfaces exhibit a multitude of satellite lines due to multi-electron excitations in which the photoinduced hole is screened by charge transfer from the metal into the low-lying unoccupied level. Recently Heskett et al. [Surface Sci. 139 (1984) 558] noticed that in the systems which display the satellite lines, the molecular vibrational frequencies decrease with increasing molecular coverage, in contrast to what is expected from dipole-dipole coupling theory. They then claimed that instead of the 2π1-metal bonding, the 5σ orbital is responsible for the bond to the substrate. This leads to a shift of the C-O stretching frequency to lower energy as the molecular coverage increases, since the 5σ orbital has an antibonding character with respect to the stretch vibration. Other experimental phenomena which should be taken into account are the negative shift and substantial broadening of the vibrational spectra of these molecules upon chemisorption on metal surfaces. Experimental results seem to reveal that the magnitude of negative shift and width increases with the strength of chemisorption, thereby suggesting that an unique mechanism is responsible for these vibrational properties. We propose a unified theory which enables us to understand these apparently unrelated electronic and vibrational properties in terms of the occupancy of the low-lying 2π1 level in the neutral ground state and in vibrational excited states of the chemisorbed molecules. Also discussed is a change of the vibrational frequencies with coverage within the framework of the chemical frequency shift caused by charge transfer between the 2π1 level and the metal. 相似文献