非下采样变换的红外与可见光图像融合

基于非下采样Contourlet变换（NSCT）,提出了一种红外和可见光图像融合算法。针对低频子带系数和各带通方向子带系数分别提出了基于图像物理特征的系数加权选择方式与基于区域能量匹配的系数选择方式,即低频基于区域梯度信息、高频基于区域特征因子的加权与选择结合的图像融合算法。实验结果表明：非下采样Contourlet变换具有较快的运算速度,且经非下采样变换后能量更加集中,可提供更多的图像信息。相对于基于像素的图像融合算法,本文的图像融合算法具有更高的融合性能,是一种更适合图像融合的多尺度几何分析（MGA）工具。     

Analysis of the orientational effects on infrared absorption spectra in p-type semiconductor quantum wells

We theoretically investigate the effects of layer orientation on valence subband optical absorption in cubic semiconductors. We analyze the polarization dependence of matrix elements for hole subband transitions at zero in-plane momentum, and make predictions concerning infrared absorption spectrum. The role of orientation as a key parameter in valence subband spectroscopy is clarified. The absorption spectra for 011 layer orientation is calculated, demonstrating the in-plane optical anisotropy.     

Image fusion based on nonsubsampled contourlet transform for infrared and visible light image

In this paper, a new method based on nonsubsampled contourlet transform (NSCT) is proposed to fuse the infrared image and the visible light image, which will produce a new fused image by which the target can be identified more easily. Firstly, two original images were decomposed into low frequency subband coefficients and the bandpass direction subband coefficients by using NSCT. Secondly, the selection of the low frequency subband coefficient and the bandpass direction subband coefficient is discussed in detail. The low frequency subband coefficients are selected based on the regional visual characteristics. For the selection of bandpass direction subband coefficients, this paper proposes a minimum regional cross-gradient method, and the cross-gradient is gained by calculating the gradient between the pixel of bandpass subbands and the adjacent pixel in the fused image of the low-frequency components. Comparison experiments have been performed on different image sets, and experimental results demonstrate that the proposed method performs better in both subjective and objective qualities.     

Studies of coupled molybdate and tungstate vibrations

The polarized Raman and infrared reflection spectra of molybdate and tungstate compounds of barium and strontium are presented and analyzed. The longitudinal and transverse frequencies of the infrared active phonons were calculated by a Kramers-Kronig analysis of the reflection curves. A strain induced forbidden mode was observed in the reflection spectra that gives interpretation of the strong shoulder on the ν₃ bands in the absorption spectra of mulled samples. The correlation field splittings of the internal modes were analyzed in terms of dipole-dipole interaction theory. The correlation field splittings of the ν₃ modes were found to be explainable in terms of dipolar coupling alone, while the splittings of the ν₂ and ν₄ modes could not be accounted for in terms of dipolar coupling.     

Raman and Infrared Spectra of Matrix Isolated CO2 and CS2

The matrix isolation infrared and Raman spectra of CO₂ and CS₂ in solid krypton at 20°K are reported. The fundamental frequencies are only very slightly red-shifted from the free gas values. Isotopic effects are found in both infrared and Raman spectra, whereas site splittings are evident in the infrared only.     

Fourier Transform Spectrum and Term Values for the CO-Stretching Mode of CD3OH Methanol

The Fourier transform infrared (FTIR) spectrum of the CO-stretching fundamental band of CD₃OH has been recorded at a resolution of 0.002 cm^-1. Assignments are reported for 35 subbands in the n = 0 ground torsional state, covering K = 0 to 9 for all torsional symmetries plus K = 10 A, and 12 assorted A and E subbands in the n = 1 first excited torsional state ranging from K = 0 up to K = 5. The subband wavenumbers have been fitted to J(J + 1) power-series energy expansions to obtain subband origins and a compact representation of the spectral observations. With the use of known ground-state energies, CO-stretch energy term values have been determined and tabulated. Least-squares fitting of the subband origins to a fourth-order Hamiltonian model for the CO-stretch mode is discussed.     

Observation of intervalley optical transitions in PbTe by magneto-photo response

Far infrared photo-response of epitaxial PbTe films at 4.2 K is found to be much more sensitive to optical transitions than reflection or transmission. Extra peaks are found which are identified as impurity induced spin-flip transitions and intervalley magnetic subband transitions.     

Hartree calculations for n-inversion layers on stressed silicon surfaces

The energy splittings and occupation number densities in n-type inversion layers are estimated in a Hartree calculation with a parametrized exponential potential. Good agreement with experiment is obtained for low temperatures and for electron concentrations 1×10¹²cm^?2 ?N_s?1×10¹³cm^?2. On the basis of these calculations the influence of uniaxial stress is considered.For a 001-stress along a (100)-surface one finds that (i) the stress induced subband splitting is a function of the electron density, and (ii) the splitting E₁-E₀ within a subband system depends on the applied stress.     

Long-wavelength phonons in the four phases of {N(CH3)4}2CuCl4 and effective charges

The temperature dependence of polar optical phonons in the four phases of tetramethylammonium tetrachlorocuprate is reported, as deduced from the analysis of infrared reflection spectra obtained via repetitive Fourier spectroscopy. Effective charges of the five constituents are also deduced from the splittings of polar modes into transverse and longitudinal components.     

Optical conductivity of multilayer graphene

The optical conductivity of graphene monolayer and multilayers are theoretically studied taking into account of the full dispersion, yielding results that are valid up to the ultraviolet region. Compared to the optical conductivity of monolayer graphene, extra peak structures appear in both the infrared and ultraviolet frequency regions for the multilayer case, which is understood as a combined effect of van Hove singularities in the energy band structures and optical transition selection rules. The number of ultraviolet peaks is equal to the number of layers. The number of infrared peaks in an even-layered graphene is equal to one half of the layer number. In odd-layered graphene, due to the existence of a monolayer-like subband, the number of infrared peaks is equal to that in the corresponding even-layered graphene with one layer less.     

Metal Isotope Natural Abundance in Infrared Spectroscopy

Band splitting can be observed in the infrared spectra of metal complexes arising from the naturally occurring mixture of isotopes, and the use of these splittings in assigning metal-ligand vibrational modes is described.     

九个苯并冠醚的13C-NMR谱研究

本文测定了九个苯并冠醚的¹³C-NMR和¹H-NMR谱,结合元素分析、红外、紫外、质谱等数据,确定了这些冠酸的分子结构。根据NMR谱的谱线位置、裂分情况及取代基诱导效应,归属了全部¹³C-NMR谱线。并讨论了苯环上不同取代基对冠醚环上各碳化学位移的影响。     

InAs/AlSb/GaSb量子阱中的双色光吸收

为了降低噪声对InAs/GaSb量子阱作为双色电探测器性能的影响,设计性能优良的光电探测器,在InAs/GaSb量子阱中加入AlSb夹层,以减少电子和空穴在界面处的复合,从而抑制由于电子和空穴复合引起的噪声。首先应用转移矩阵方法求解薛定谔方程得到量子阱中电子和空穴的能级和波函数,研究AlSb夹层对电子和空穴波函数的影响。应用平衡方程方法求解外加光场条件下的玻尔兹曼方程,研究所有电子和空穴跃迁通道对光吸收系数的贡献,重点研究了AlSb夹层厚度对光吸收系数的影响。结果表明:基于In As/GaSb的量子阱体系可以实现双色光吸收,加入AlSb夹层可以有效抑制电子和空穴在界面处的隧穿,从而降低复合噪声,同时AlSb夹层的加入也对吸收峰有影响。AlSb夹层的厚度达到2 nm即可有效降低电子和空穴复合噪声,双色光吸收峰在中远红外波段,为该量子阱作为性能良好的中远红外光电探测器提供理论支撑。     

Photoluminescence lineshape features of carbon δ-doped GaAs heterostructures

Photoluminescence lineshape properties of quasi-two-dimensional electron systems in setback δ-doped GaAs heterostructures are studied at liquid helium temperature. Contributions from the ground and the first excited two-dimensional subband are clearly observed. A simple fit to the lineshape including broadening demonstrates that there is an exponential low-energy tail associated with the ground subband. No such tail is observed for the first excited subband. The fit precisely reveals the subband bottom energies, the Fermi energy, the electron temperature and the recombination intensities. A self-consistent calculation of subband properties including the potential contribution of the setback δ-doping reproduces well the subband properties and the recombination intensities.     

Fourth-order magnetic anisotropy and tunnel splittings in Mn(12) from spin-orbit-vibron interactions

From density-functional-theory based methods, we calculate the vibrational spectrum of the Mn(12)O(12)(COOH)(16)(H(2)O)(4) molecular magnet. Calculated infrared intensities are in accord with experimental studies. There have been no ab initio attempts at determining which interactions account for the fourth-order anisotropy. We show that vibrationally induced distortions of the molecule contribute to the fourth-order anisotropy Hamiltonian and that the magnitude and sign of the effect (-6.2 K) is in good agreement with all experiments. Vibrationally induced tunnel splittings in isotopically pure and natural samples are predicted.     

Electron-electron interaction effects in bismuth

Measurements of the far infrared magneto-optical transmission spectra of bismuth at 311 and 337 μ and in fields up to 100 kG at 4°K are described. The sensitivity of the spectra of transmitted magneto plasma waves to the electron scattering in bismuth is discussed. Particular attention is drawn to excitonic effects associated with weakly allowed hole cyclotron resonance absorption lines observed in the spectra. A simple Cooper pair like argument is given to illustrate the nature of these inter subband excitons. The features entering into a more complete theory of the excitons are also briefly discussed.     

A Gabor subband decomposition ICA and MRF hybrid algorithm for infrared image reconstruction from subpixel shifted sequences

An image blind reconstruction, as a blind source separation problem, has been solved recently by independent component analysis (ICA). Based on ICA theory, in this paper, a high resolution image is reconstructed from low resolution and subpixel shifted sequences captured by infrared microscan imaging system. The algorithm has the attractive feature that neither the prior knowledge of the blur kernel nor the value of subpixel misregistrations between the input channels is required. The statistical independence in the image domain is improved by the multiscale Gabor subband decompositions, which are designed for the best ability to cover the whole spatial frequency and to avoid overlapping between the subbands. The mutual information is employed to locate a subband with the least dependent components. In terms of MAP estimator, we combine the super-Gaussian with Markov random field to form a hybrid image distribution. This strategy helps to estimate the separating matrix reasonable to extract the sources with the image properties, that is, sharp enough as well as correlative in local area. The proposed algorithm is capable of performing high resolution image sources which are not strictly independent, and its viability is proved by the computer simulations and real experiments.     

Intersubband photocurrent from double barrier resonant tunneling structures

Simple models of semiconductor-based double barrier resonant tunneling structures predict a large accumulation of charge carriers in the structure. These carriers can be excited optically from one subband to another generating photocurrent. In this work we have investigated the photo-induced current due to intersubband excitation in double barrier structures. We have found that the origin of the photocurrent is accumulation of quantized carriers in the emitter-barrier junction of the structure, rather than accumulation of carriers in the double barrier quantum well. This photon assisted tunneling process in double barrier structures may be used for infrared detection.     

Infrared and raman spectra of barium nitrite monohydrate

The low temperature infrared absorption and room temperature laser Raman spectra of polycrystalline Ba(NO₂)₂ · H₂O and its deuterated analogue are studied. The strongly bonded H-atom of the water molecule makes a highly bent H-bond while the weakly bonded H-atom exhibits a slightly bent (or possible bifurcated) bond consistent with recent structural data; the H-bond enthalpies are estimated to be 3.3 and 2.1 $\text{KCal}\text{mole}$ respectively. The wagging, twisting and rocking modes of the water molecule have been assigned using several well known criteria. The force constants of these modes have also been computed. The librational splittings observed at low temperature are consistent with polarization data, and are being attributed to infrared active factor group components.     

Negative FIR-photoconductivity in n-GaAs

Negative photoconductivity in n-GaAs has been observed in the far infrared spectral range between 20 and 29 cm^–1. Negative photoconductivity occurs when a magnetic field is applied to the samples and impact ionization of shallow donors by the electric bias field is the dominant mechanism of electron excitation to the conduction band. A conceivable model qualitatively explaining the experimental results is proposed, which involves optical transitions from the lowest Landau subband to higher bound states of shallow donors.