共查询到20条相似文献,搜索用时 31 毫秒
1.
Petrov M. P. Voitylov V. V. Klemeshev S. A. Trusov A. A. 《Optics and Spectroscopy》2011,111(5):832-840
We present the results of our experimental investigation of light scattering by polydisperse colloids of diamond and graphite.
The scattering is studied at a random orientation of particles and in an external radiofrequency electric field, which orients
particles along the strength. The average dimensions of particles in both colloids are close to each other and comparable
with the wavelength of the incident light. The shape of particles and the optical and electrooptical properties of diamond
and graphite colloids are significantly different. We analyze the polarization components of scattered light energy when the
light incident on the colloids is linearly polarized. We show that the quadrupole light scattering by isotropic diamond particles
has the main effect on angular dependences of depolarization of scattered light. For light scattering by anisotropic graphite
particles, the depolarization of scattered light is mainly determined by a particular feature of the dipole scattering of
particles. It is shown that, in both colloids, the orientational order of particles considerably reduces the depolarization
of light scattered by particles. We show that relative changes in the intensity and depolarization of scattered light, which
depend on the scattering angle and polarization direction of light, as well as on the parameters of particles, can be used
as a measure of electrooptical effects observed in colloids. 相似文献
2.
Amélie Juhin Christian Brouder Frank de Groot 《Central European Journal of Physics》2014,12(5):323-340
A spherical tensor expansion is carried out to express the resonant inelastic scattering cross-section as a sum of products of fundamental spectra with tensors involving wavevectors and polarization vectors of incident and scattered photons. The expression presented in this paper differs from that of the influential article by Carra et al. (Phys. Rev. Lett. 74, 3700, 1995) because it does not omit interference terms between electric dipole and quadrupole contributions when coupling each photon to itself. Some specific cases of the spherical tensor expansion are discussed. For example the case of isotropic samples is considered and the cross-section is expressed as a combination of only three fundamental spectra for the situation where electric dipole or electric quadrupole transitions in the absorption process are followed by electric dipole transitions in the emission. This situation includes the case of untextured powder samples, which corresponds to the most frequent situation met experimentally. Finally, it is predicted that some circular dichroism may be observed on isotropic samples provided that the circular polarization of the scattered beam can be detected. 相似文献
3.
Selection rules for electric multipole transition of diatomic molecule in scattering experiments
下载免费PDF全文
![点击此处可从《中国物理 B》网站下载免费的PDF全文](/ch/ext_images/free.gif)
The knowledge of the energy level structures of atoms and molecules is mainly obtained by spectroscopic experiments.Both photoabsorption and photoemission spectra are subject to the electric dipole selection rules(also known as optical selection rules). However, the selection rules for atoms and molecules in the scattering experiments are not identical to those in the optical experiments. In this paper, based on the theory of the molecular point group, the selection rules are derived and summarized for the electric monopole, electric dipole, electric quadrupole, and electric octupole transitions of diatomic molecules under the first Born approximation in scattering experiments. Then based on the derived selection rules, the electron scattering spectra and x-ray scattering spectra of H2, N2, and CO at different momentum transfers are explained, and the discrepancies between the previous experimental results measured by different groups are elucidated. 相似文献
4.
分析光场与高聚物相互作用的微观机制,介绍高分子与小分子在光场作用下的极化过程。对在窄束光场作用下,高分子链极化后链上各处极化程度的分布情况进行研究,指出对于高度拉伸的聚合物薄膜,电偶极子模型不适合准确解释高分子与光场相互作用的微观机制。为此,采用符合实际的天线模型分析高分子天线与窄束光场的相互作用,从理论上推导出天线模型高分子链上一小段的极化公式,并用离散变分方法——DVM(discrete variational method)计算一个高分子链的极化分布,验证了文中推导出的分式的合理性。最后,将极化分布看作是电流在天线上的分布,计算了天线的次级辐射在空间中的角分布,得到天线模型对电偶极子模型的修正因子。 相似文献
5.
S. Woźniak 《Molecular physics》2013,111(13-14):1975-1982
A static magnetic field, acting on an isotropic medium composed of paramagnetic chiral molecules perpendicular to the propagation direction of the optical beam, is shown to induce an axial differential effect—magnetochiral Rayleigh light scattering. Diamagnetic and paramagnetic contributions to the effect are given in terms of the linear and nonlinear electric dipole, magnetic dipole and electric quadrupole polarizabilities responsible also for natural optical activity, the Faraday effect as well as magnetochiral birefringence. Specific cases are discussed. 相似文献
6.
M. Yu. Barabanenkov Yu. N. Barabanenkov 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2018,12(1):7-10
To solve the problems of the repeated scattering of electromagnetic waves at ensembles of dielectric particles taking into account their conductivity, the interaction between collective optical modes of 2D embedded chains of small spherical plasmonic particles, which are characterized by electric dipole coupling, is analytically described on the basis of the quasi-separable T-scattering operator approach. It is assumed that the polarization vector of the electric field of an incident wave is oriented perpendicular to the plane of particle chains. The mutual influence of currents is demonstrated using a regular triangle whose vertices and center of symmetry contain particles and two embedded square chains with eight particles located at their vertices. 相似文献
7.
Strong near-field couplings of anapole modes and formation of higher-order electromagnetic modes in stacked all-dielectric nanodisks
下载免费PDF全文
![点击此处可从《中国物理 B》网站下载免费的PDF全文](/ch/ext_images/free.gif)
We theoretically study the near-field couplings of two stacked all-dielectric nanodisks, where each disk has an electric anapole mode consisting of an electric dipole mode and an electric toroidal dipole (ETD) mode. Strong bonding and anti-bonding hybridizations of the ETD modes of the two disks occur. The bonding hybridized ETD can interfere with the dimer's electric dipole mode and induce a new electric anapole mode. The anti-bonding hybridization of the ETD modes can induce a magnetic toroidal dipole (MTD) response in the disk dimer. The MTD and magnetic dipole resonances of the dimer form a magnetic anapole mode. Thus, two dips associated with the hybridized modes appear on the scattering spectrum of the dimer. Furthermore, the MTD mode is also accompanied by an electric toroidal quadrupole mode. The hybridizations of the ETD and the induced higher-order modes can be adjusted by varying the geometries of the disks. The strong anapole mode couplings and the corresponding rich higher-order mode responses in simple all-dielectric nanostructures can provide new opportunities for nanoscale optical manipulations. 相似文献
8.
I. B. Khriplovich 《Physics of Atomic Nuclei》2001,64(3):516-524
Several problems concerning the deuteron and having simple analytic solutions are considered. The relation between the electric quadrupole moment of the deuteron and the np scattering amplitude is established. The degree of the circular polarization of the photon emitted in the radiative capture of longitudinally polarized thermal neutrons is found. The anapole, electric dipole, and magnetic quadrupole moments of the deuteron are calculated. 相似文献
9.
《Journal of Electron Spectroscopy and Related Phenomena》2002,125(1):47-56
Photoelectron diffraction effects may be strongly influenced by optical properties of the solid. Due to refraction and absorption of light at a surface, the state of polarization of light may be changed and, therefore, the corresponding photoelectron diffraction intensity. In order to include optical properties of solids in photoelectron diffraction theory, a general polarization vector of light is defined taking into account both refraction and absorption of light at the vacuum–solid boundary. In a first step, the radiation field of light inside the solid is approximated macroscopically according to classical electrodynamics. Analytical expressions are derived within a real-angle representation of Fresnel equations to reveal the influence of refraction and absorption of light on the state of polarization of light. A general refractive index in dependence on the incident angle of light is introduced which determines the refractive angle inside the solid (refraction law with real angles) and the order of influence of absorption of light. The general polarization vector is applied in the calculation of dipole transition matrix elements in a multiple-scattering cluster model of photoelectron diffraction, where the process of photoabsorption (dipole transition matrix element) and multiple scattering processes of photoelectrons (scattering path operator) are considered separately. Different analytical and numerical results of photoelectron diffraction effects are presented for light of general polarization incident at general angles taking into account the optical properties of the solid. Examples are shown and discussed in detail for Cu(001) and GaAs(110) surfaces. 相似文献
10.
We discuss optical absorption in topological insulators and study possible photoelectric effects theoretically. We found that absorption of circularly polarized electromagnetic waves in two-dimensional topological insulators results in electric current in the conducting 1D edge channels, the direction of the current being determined by the light polarization. We suggest two ways of inducing such a current: due to magnetic dipole electron transitions stimulated by irradiation of frequency below the bulk energy gap, and due to electric dipole transitions in the bulk at frequencies larger than the energy gap with subsequent capture of the photogenerated carriers on conducting edge states. 相似文献
11.
空心方形纳米结构能够激发更大面积的增强电场,故其可以作为衬底用于表面增强拉曼散射.应用离散偶极子近似算法研究了空心方形银纳米结构的消光光谱及其近场电场分布与入射光偏振方向之间的关系.研究表明,空心方形银纳米结构的表面等离子体共振峰不随入射光偏振方向的改变而移动,但是其表面增强电场分布却强烈地依赖于入射光的偏振方向.另外,还讨论了空心方形银纳米结构间的耦合作用对其表面等离子体共振模式的影响.结果发现,可以通过调节结构间的距离来改变结构间的耦合作用,同时改变了表面等离子体共振峰的位置.这些结果将为理解闭合纳米
关键词:
空心方形银纳米结构
表面等离子体
偏振
电场耦合 相似文献
12.
《Annals of Physics》1980,127(1):179-197
The renormalization procedure of perturbation theory is applied to study polariton effects in the optical processes involving photons with energies near that of an exciton: resonant Raman scattering, resonant electronic Raman scattering, and resonant high — order optical harmonic generation. To demonstrate the general method and the computation technique we consider in this work a simple model with the following properties: (a) The semiconductor has a direct band gap with allowed electrical dipole transition and with nondegenerate valence and conduction bands. (b) We consider only the photons in a definite polarization state; they are in resonance with one bound state of an electron-hole pair, and we take into account only the transition between this exciton state and the photon in the given polarization state. We work in the framework of the Green's function approach and we shall see that this approach provides for the inclusion of damping effects in a relatively rigorous manner. 相似文献
13.
14.
Rainer W Hasse 《Pramana》1978,11(4):441-455
The polarization of the fragments from binary fission or of scattering or fusioning heavy nuclei is investigated in the liquid
drop model. Due to the mutual Coulomb repulsion near contact the fragments may be polarized with respect to their charges
(electric dipole moments from inhomogeneous charge distributions) as well as with respect to their shapes (quadrupole and
octupole deformations). The lowering of the minimum energy near contact due to charge polarization is in the order of 1 MeV
if one takes into account the energy from the giant dipole restoring force derived from the volume symmetry energy in addition
to the liquid drop energies. The question whether one obtains prolate or oblate shapes is entirely due to the restriction
in deformation space (fixed distance between centers-of mass or between the tips of the fragments). 相似文献
15.
In this Letter, we study the emission properties of an electric dipole emitter coupled to a plasmonic spiral structure. The plasmonic spiral structure functions as an optical antenna, coupling the electric dipole emission into circularly polarized unidirectional emission in the far field. Increasing number of turns of the spiral leads to narrower angular width of the emission pattern in the far field. For a spiral antenna with six turns, antenna directivity of 23.5 dB with a directional emission into a narrow angular cone of 4.3° can be achieved. The emitted photons carry spin that is essentially determined by the handedness of the spiral antenna. By reversing the spiral, one can switch the polarization of the emission field between left-hand and right-hand circular polarizations. The spiral antenna may be used as a nanoscale circular polarization source in single molecule sensing, single-photo sources, and integrated photonic circuits. 相似文献
16.
17.
D. V. Permyakov I. S. Mukhin I. I. Shishkin A. K. Samusev P. A. Belov Yu. S. Kivshar 《JETP Letters》2014,99(11):622-626
We study, both experimentally and theoretically, the scattering of electromagnetic waves by a subwavelength hole fabricated in a thin metallic film. We employ the scanning near-field optical microscopy in order to reconstruct experimentally the full three-dimensional structure of the electromagnetic fields in the vicinity of the hole. We observe an interference of all excited waves with an incident laser beam which allows us to gain the information about the wave phases. Along with the well-known surface plasmon polaritons propagating primarily in the direction of the incident beam polarization, we observe the free-space radiation diffracted by the hole. We compare the experimental results with the fields of pure electric and pure magnetic dipoles as well as with direct numerical simulations. We confirm that a single hole in a thin metallic film excited at the normal incidence manifests itself as an effective magnetic dipole in the visible spectral range. 相似文献
18.
Hyperfine interaction between electron spin and randomly oriented nuclear spins is a key issue of electron coherence for quantum information/computation. We propose an efficient way to establish high polarization of nuclear spins and reduce the intrinsic nuclear spin fluctuations. Here, we polarize the nuclear spins in semiconductor quantum dot(QD) by the coherent population trapping(CPT) and the electric dipole spin resonance(EDSR) induced by optical fields and ac electric fields. By tuning the optical fields, we can obtain a powerful cooling background based on CPT for nuclear spin polarization. The EDSR can enhance the spin flip–flop rate which may increase the cooling efficiency. With the help of CPT and EDSR, an enhancement of 1300 times of the electron coherence time can be obtained after a 10-ns preparation time. 相似文献
19.
A.A. Zabolotskii 《Physica D: Nonlinear Phenomena》2008,237(4):540-550
We develop the inverse scattering transform for the recently found integrable system of reduced Maxwell-Bloch equations with two components of polarization and with an anisotropic dipole momentum. The model describes few-cycle pulses of optical or other field propagations. We find that the existence of a nontrivial group of symmetry of the corresponding Lax pair leads to a particular form of the inverse scattering transform equations. We show that solutions can be expressed in terms of the solution of a matrix Riemann-Hilbert problem formulated for the complex plane with a nontrivial group of automorphisms. 相似文献