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排序方式: 共有61条查询结果,搜索用时 15 毫秒
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2.
M. Marlo-Helle A. Harju R.M. Nieminen 《Physica E: Low-dimensional Systems and Nanostructures》2005,26(1-4):286
We study ground states and far-infrared spectra (FIR) of two electrons in four-minima quantum-dot molecule in magnetic field by exact diagonalization. Ground states consist of altering singlet and triplet states, whose frequency, as a function of magnetic field, increases with increasing dot–dot separation. When the Zeeman energy is included, only the two first singlet states remain as ground states. In the FIR spectra, we observe discontinuities due to crossing ground states. Non-circular symmetry induces anticrossings, and also an additional mode above ω+ in the spin-triplet spectrum. In particular, we conclude that electron–electron interactions cause only minor changes to the FIR spectra and deviations from the Kohn modes result from the low-symmetry confinement potential. 相似文献
3.
4.
I. Mukhopadhyay R. M. Lees W. Lewis-Bevan J. W. C. Johns F. Strumia G. Moruzzi 《International Journal of Infrared and Millimeter Waves》1987,8(11):1483-1502
High-resolution infrared (IR) and far infrared (FIR) Fourier transform absorption spectra have been employed to investigate assignments of FIR laser lines reported from optically-pumped13CH3OH. The spectroscopic measurements are used in conjunction with the reported IR pump and FIR laser frequencies to form closed combination loops for several systems, serving to confirm the assignments and in some cases to improve the accuracy of the FIR laser frequencies. Frequency predictions from combination differences are also presented for a number of potential new FIR laser lines. 相似文献
5.
We present a region of interest (ROI) generation method specialized for nighttime pedestrian detection using far-infrared (FIR) images. Because pedestrians typically appear brighter than background in FIR images, previous research efforts primarily attempted to extract ROIs based on the intensity threshold. However this approach has problems resulting from the intensity variances of pedestrians due to their clothing and, especially in urban scenarios, and other heat sources that emit more heat than the pedestrians. In this paper, we propose a novel ROI generation method that is based on combining image segments instead of using the intensity threshold. In order to minimize dependence on brightness, we utilize the low-frequency characteristics of FIR images. As a result, our proposed method generates a small number of ROIs at an acceptable miss rate and the generated ROIs provide advantages for classification because the pedestrians are satisfactorily arranged within a bounding box. Experiments conducted indicate that our proposed method performs reliably in urban scenarios. 相似文献
6.
Vidar Gudmundsson Ingibjrg Magnúsdttir Sigur
ur I. Erlingsson 《Physica E: Low-dimensional Systems and Nanostructures》1998,1(1-4)
We study the optical absorption of arrays of quantum dots and antidots in a perpendicular homogeneous magnetic field. The electronic system is described quantum mechanically using a Hartree approximation for the mutual Coulomb interaction of the electrons. The evolution of the absorption is traced from the homogeneous to the strongly modulated case identifying the ensuing collective modes, the magnetoplasmons, and their correlations with inherent length scales of the system. 相似文献
7.
A. De Michele K. Bousbahi G. Carelli A. Moretti 《International Journal of Infrared and Millimeter Waves》2003,24(10):1649-1654
We have investigated CHD2OH methanol as source of far-infrared (FIR) laser radiation using the optical pumping technique. Our new waveguide pulsed CO2 laser, with peak powers as high as some kW, has allowed us to observe 12 new lines. Each of them is characterized in wavelength, relative polarization, intensity, optimum operating pressure and pump offset from the center of the exciting CO2 line. 相似文献
8.
In this paper, we report 30 THz measurements of ammonia in its excited, ν2 = 1, inversion state. These measurements include transition frequencies and pressure shifts (where significant enough to be observed). Included in the data are two forbidden and three ro-inversion transitions, as well as 18 transitions never directly measured before. The measurements were made with an all-solid-state, diode-laser, difference-frequency spectrometer. Using an innovative laser-frequency locking scheme, this spectrometer provided accurately determined and continuously tuned THz-frequencies without requiring accurate knowledge of the absolute laser frequencies. The details of the spectrometer’s frequency calibration is discussed. A global analysis of NH3 based on the available ground state, ν2 = 1 state, and ν2-band transitions was carried out, and the resulting set of recommended molecular effective-Hamiltonian parameters for ammonia is presented. In addition, calculated center frequencies and intensities for all possible transitions up to J = 20 between rotation, inversion, and vibration levels in the ground and ν2 = 1 states are included as supplementary material. 相似文献
9.
W. Chen R. Rocquet J. Burie D. Boucher 《International Journal of Infrared and Millimeter Waves》1997,18(1):217-232
A submillimeter-wave/far-infrared (SMM/FIR) laser sideband heterodyne spectrometer has been built for molecular rotational
spectroscopy application in the frequency range of 600–3000 GHz. Based on Gaussian optics, optical system of the spectrometer
is designed to be quasi-achromatic and low losses. In this article the optical design and the performance of the spectrometer
are presented. 相似文献
10.
ZnSe: Fe2+中的动态Jahn-Teller效应和远红外光谱的研究 总被引:1,自引:0,他引:1
推导了3d^4/3d^6离子基态5D在立方晶体场,自旋-轨道耦合和动态Jahn-Teller效应作用下的哈密顿矩阵,并用对角化该哈密顿矩阵的方法研究了Fe^2+在ZnSe中的远红外光谱,理论计算与实验符合得好,研究表明,在ZnSe:Fe^2+中,比晶体场理论分析多出的分裂谱线是Fe^2+与ZnSe晶格间的动态Jahn-Teller效应引起的,还预测了其它Jahn-Teller效应分裂谱,所推导的哈密顿矩阵对研究3d^4/3d^6离子在立方晶体中的精细光谱,电子顺磁共振谱和动态Jahn-Teller分裂都是有用的。 相似文献