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1.
This paper studies in detail the interaction of two edge dislocations nested in a Gaussian beam propagating in free space. It shows that in free-space propagation the edge dislocations are unstable and vanish, and two noncanonical vortices with opposite topological charge take place when off-axis distances c1 and c2 of two edge dislocations are non-zero, and the condition k2w08+32c1c2(w02-2c1c2)z2>0 is fulfilled (k-wave number, w0-waist width). A noncanonical vortex appears when one off-axis distance is zero. However, one edge dislocation is stable when two edge dislocations are perpendicular and one off-axis distance is zero. Two perpendicular edge dislocations both with zero off-axis distance are also stable. The analytical results are illustrated by numerical examples. 相似文献
2.
For a Bose--Einstein condensate (BEC) confined in a double lattice
consisting of two weak laser standing waves we find the Melnikov
chaotic solution and chaotic region of parameter space by using the
direct perturbation method. In the chaotic region, spatial evolutions
of the chaotic solution and the corresponding distribution of
particle number density are bounded but unpredictable between their
superior and inferior limits. It is illustrated that when the
relation k1\approx k2 between the two laser wave vectors is
kept, the adjustment from k21 to k2\ge k1 can
transform the chaotic region into regular one or the other way round.
This suggests a feasible scheme for generating and controlling chaos,
which could lead to an experimental observation in the near future. 相似文献
3.
Electronic structures and optical properties of Zn-doped β-Ga2O3 with different doping sites 总被引:2,自引:0,他引:2 下载免费PDF全文
<正>The electronic structures and optical properties of intrinsicβ-Ga2O3 and Zn-dopedβ-Ga2O3 are investigated by first-principles calculations.The analysis about the thermal stability shows that Zn-dopedβ-Ga2O3 remains stable. The Zn doping does not change the basic electronic structure ofβ-Ga2O3,but only generates an empty energy level above the maximum of the valence band,which is shallow enough to make the Zn-dopedβ-Ga2O3 a typical p-type semiconductor.Because of Zn doping,absorption and reflectivity are enhanced in the near infrared region.The higher absorption and reflectivity of ZnCa(2) than those of ZnCa(1)are due to more empty energy states of ZnCa(2)than those of ZnCa(1) near Ef in the near infrared region. 相似文献
4.
Spectroscopic parameters and molecular constants of HI(X~1Σ~+),DI(X~1Σ~+) and TI(X~1Σ~+) isotope molecules 下载免费PDF全文
The potential energy curve (PEC) of HI(X1Σ+) molecule is studied using the complete active space self-consistent field method followed by the highly accurate valence internally contracted multireference configuration interaction approach at the correlation-consistent basis sets, aug-cc-pV6Z for H and aug-cc-pV5Z-pp for I atom. Using the PEC of HI(X1Σ+), the spectroscopic parameters of three isotopes, HI(X1Σ+), DI(X1Σ+) and TI(X1Σ+), are determined in the present work. For the HI(X1Σ+), the values of D0, De, Re, ωe, ωeχe, αe and Be are 3.1551 eV, 3.2958 eV, 0.16183 nm, 2290.60 cm-1, 40.0703 cm-1, 0.1699 cm-1 and 6.4373 cm-1, respectively; for the DI (X1Σ+), the values of D0, De, Re, ωe, ωeχe, αe and Be are 3.1965 eV, 3.2967 eV, 0.16183 nm, 1626.8 cm-1, 20.8581 cm-1, 0.0611 cm-1 and 3.2468 cm-1, respectively; for the TI (X1Σ+), the values of D0, De, Re, ωe, ωeχe, αe and Be are of 3.2144 eV, 3.2967 eV, 0.16183 nm, 1334.43 cm-1, 14.0765 cm-1, 0.0338 cm-1 and 2.1850 cm-1, respectively. These results accord well with the available experimental results. With the PEC of HI(X1Σ+) molecule obtained at present, a total of 19 vibrational states are predicted for the HI, 26 for the DI, and 32 for the TI, when the rotational quantum number J is equal to zero (J = 0). For each vibrational state, vibrational level G(?), inertial rotation constant B? and centrifugal distortion constant D? are determined when J = 0 for the first time, which are in excellent agreement with the experimental results. 相似文献
5.
In this paper, we propose a novel Schottky barrier MOSFET structure,
in which the silicide source/drain is designed on the buried metal
(SSDOM). The source/drain region consists of two layers of silicide
materials. Two Schottky barriers are formed between the silicide
layers and the silicon channel. In the device design, the top barrier
is lower and the bottom is higher. The lower top contact barrier is
to provide higher {on-state} current, and the higher bottom contact
barrier to reduce the off-state current. To achieve this, ErSi is
proposed for the top silicide and CoSi2 for the bottom in the
n-channel case. The 50~nm n-channel SSDOM is thus simulated to
analyse the performance of the SSDOM device. In the simulations, the
top contact barrier is 0.2e~V (for ErSi) and the bottom barrier is
0.6eV (for CoSi2. Compared with the corresponding conventional
Schottky barrier MOSFET structures (CSB), the high on-state
current of the SSDOM is maintained, and the off-state current is
efficiently reduced. Thus, the high drive ability (1.2mA/μm
at Vds=1V,
Vgs=2V) and the high Ion/Imin ratio (106)
are both achieved by applying the SSDOM
structure. 相似文献
6.
A 2× 2 electro-optic switch is experimentally demonstrated
using the optical structure of a Mach--Zehnder interferometer (MZI) based
on a submicron rib waveguide and the electrical structure of a PIN diode on
silicon-on-insulator (SOI). The switch behaviour is achieved through
the plasma dispersion effect of silicon. The device has a modulation arm
of 1~mm in length and cross-section of 400~nm× 340~nm. The
measurement results show that the switch has a VπLπ
figure of merit of 0.145~V\cdot cm and the extinction ratios of two
output ports and cross talk are 40~dB, 28~dB and -28~dB,
respectively. A 3~dB modulation bandwidth of 90~MHz and a switch
time of 6.8~ns for the rise edge and 2.7~ns for the fall edge are also
demonstrated. 相似文献
7.
The atomic and electronic structures of Pb bilayer/Pt(111) are investigated with two theoretical calculations.We find that the stable (2 × 2)/(3 × 3) Pb/Pt(111) structure is a promising candidate for being used as a template with self-organized ordered Pb semi-cluster array on the first Pb monolayer.This stable structure can realize the ordered Au single-atom array around the Pb semi-clusters that can cause selective adsorption of noble atoms.The size of Pb magic number semi-cluster plays a more important role in determining the periodicity of the template than the lattice constant misfit between the substrate and the overlayer.This leads to quite a different periodicity between the two stable templates,which are (2 × 2)/(3 × 3) Pb/Pt(111) and Pb/Cu(111).Therefore,by considering the size of the stable semi-clusters and carefully selecting different substrate materials,we can tune the density of Pb semi-clusters as the nucleation points and then tune the periodicity of the stable template. 相似文献
8.
Considering that pressure-induced formation of short,strong covalent bonds in light-element compounds can produce superhard materials,we employ structure searching and first-principles calculations to predict a new class of boron nitrides with a stoichiometry of BN2,which are stable relative to alpha-B and alpha-N2 at ambient pressure.At ambient pressure,the most stable phase has a layered structure(h-BN2) containing hexagonal BN layers between which there are intercalated N2 molecules.At 25 GPa,a three-dimensional P42/mmc structure with single N-N bonds becomes the most stable.Dynamical,thermal,and mechanical stability calculations reveal that this structure can be recovered under ambient conditions.Its calculated stress-strain relations demonstrate an intrinsic superhard nature with an estimated Vickers hardness of ~43 GPa.This structure has a potentially high energy density of ~4.19 kJ/g. 相似文献
9.
Infrared diode laser spectroscopy of O2–N2O van der Waals complex in the ν1 symmetric stretch region of N2O 下载免费PDF全文
The rovibrational spectrum of O2–N2O van der Waals complex is measured in the v1 symmetric stretch region of N2O monomer using a tunable diode laser spectrometer. The complex is generated by a slit-pulsed supersonic expansion with gas mixtures of O2, N2O, and He. Both a- and b-type transitions are observed. The effective Hamiltonian for an open-shell complex consisting of a diatomic molecule in a 3Σ electronic state and a closed-shell partner is used to analyze the observed spectrum. Molecular constants in the vibrationally excited state are determined accurately. The band-origin of the spectrum is determined to be 1284.7504(25) cm-1, red-shifted from that of the N2O monomer by ~ 0.1529 cm-1. 相似文献
10.
In this paper, by using resonance enhanced (2+1) multiphoton ionization (REMPI) of AsH3 and detecting the daughter molecular ions AsH+ and As+, a long progression discrete structure was obtained from 267 to 291 nm, which obeys the formula ν0(cm-1)=68875.3+504.1v′2+5.26v′22. Analysis of the spectrum has revealed that it belongs to 4d Rydberg state transition. Our assignment yields the 4d Rydberg state parameters Te′=67881.1 cm-1, ωe′=495.1 cm-1 and δ=0.962. Finally the 4d Rydberg state structure of AsH3 was discussed. 相似文献
11.
采用内收缩多参考组态相互作用方法和相关一致基aug-cc-pV6Z, 对BF自由基X1∑+和a3∏ 态的势能曲线进行了研究. 计算是在0.095---1.33 nm的核间距内进行的. 为获得更准确的结果, 计算中还考虑了Davidson修正、相对论修正及核价相关修正对势能曲线的影响. 相对论修正采用的方法是二阶DouglasKroll哈密顿近似, 修正计算是在cc-pV5Z基组水平上进行的. 核价相关修正使用的是cc-pCV5Z基组. 利用得到的势能曲线, 拟合出了各种修正下BF自由基X1∑+和a3∏ 态的光谱常数De, Re, ωe, ωexe, ωeye, Be和αe、并与实验结果进行了比较. 结果表明: 考虑Davidson修正、相对论修正和核价相关修正后得到的光谱常数最接近实验结果. 利用修正后的势能曲线, 通过求解径向振转Schrödinger方程, 找到了转动量子数J = 0时这两个电子态的全部振动态, 并计算了每一电子态前20个振动态的振动能级、惯性转动常数和离心畸变常数, 其值与已有的实验结果较为一致. 本文得到的光谱常数和分子常数达到了很高的精度, 能为进一步的光谱实验提供可靠的参考. 相似文献
12.
13.
14.
V. S. Zuev A. V. Kanaev L. D. Mikheev D. B. Stavrovskii 《Journal of Russian Laser Research》1982,3(4):287-302
The operating principle of a photodissociation XeF laser (λ?350 nm) is discussed. A laser operating on the gas mixture XeF2:N2(SF6):Ar pumped by radiation from an open high-current discharge is described. The maximum lasing duration is 5 μsec, the maximum output energy is 0.15 J. The vibrational structure of the XeF-molecule transition B2Σ1/2 + ? X2Σ1/2 +, observed in absorption, luminescence, and stimulated emission, is investlgated. The vibrational quantum and the anharmonicity in the upper and lower states are measured: ωe ' = 308.7 cm-1, ωe 'xe ' = 1.44 cm-1, ωe '' = 225.7 cm-1, ωe ''xe '' = 11.0 cm-1. The difference between the equilibrium internuclear distances of the XeF molecule is determined for the excited (B) and ground (X) states, namely re ' - re '' = 0.33 +- 0.01 Å. 相似文献
15.
Rotationally-resolved bands leading to a Rydberg state R 0 u + of molecular I2 are observed in a two-stage, three-photon transition from the ground state. The R 0 u + state interacts homogeneously with high vibrational levels, νF ≈ 200–250, of an ionic state F 0 u +, the perturbation being directed by the vibrational overlap integrals towards even-numbered vibrational levels of R. Spectral constants of R 0 u + are (in cm-1): T e = 61665·15, ωe = 209.29, ωe x e = 0·859, B e = 0·03842 and αe = 1·6 × 10-4. The electronic matrix element for the R, F interaction (excluding one deviant result) is |W e| = 107 ± 1 cm-1; thus W e/ωe ≈ 0·5, corresponding to ‘intermediate’ coupling. Energy considerations indicate that R should be assigned to the 0 u + state of either the configuration (2430 Π1/2g )6pσ u , or of (2421 4Σ u -)6sσ g . This state is the first extra-valence state of I2 to be rotationally analysed. 相似文献
16.
Soulef Jellali Leila Mejrissi Mahmoud Mohery Brahim Oujia Florent Xavier Gadéa 《Molecular physics》2013,111(20):2910-2923
ABSTRACTThe structural and electronic properties of (SrLi)+ molecular ion have been determined by the use of ab initio approaches. Potential energy curves (PECs) with their spectroscopic constants (Re, De, ωe, Te, Be and ωeχe) have been calculated. Also, the vibrational properties and the electric dipole moments, either permanent (PDM) or transition (TDM) ones, have been investigated and analysed. Large Gaussian basis sets, the full valence configuration interaction (FCI) and the formalism of non-empirical pseudo-potential including the two approaches, effective core potential (ECP) and core polarisation potential (CPP), are analysed. Therefore, (SrLi)+ is considered as a two effective electrons system. Numerous excited states of symmetries 1,3Σ+, 1,3Π and 1,3Δ dissociating below the ionic limit Sr2+Li? have been investigated. This study shows interesting behaviours around the avoided crossing related to charge transfer involving important processes in physics and astrophysics such as dynamics, pre-dissociation and inelastic transitions. 相似文献
17.
使用对称性匹配簇-组态相互作用方法首次计算了Li2分子自旋一致激发态a3Σ+u和b3Πu的离解能、平衡几何及其谐振频率。使用最小二乘法、利用Murrell-Sorbie函数形式拟合出了Li2分子三重态的第一激发态a3Σ+u 和第二激发态b3Πu的完整势能函数,并计算了这两个态的光谱常数 (Be, αe, ωe 和 ωeχe) 和力常数 (f2, f3和f4)。得到了Murrell-Sorbie函数形式既适用于基态、又适用于激发态的结论。将计算得到的激发态(a3Σ+u和b3Πu)的离解能、平衡几何及其谐振频率与实验结果及其它理论计算结果进行了比较。从比较的结果中可以清楚地看出,本文的计算结果在计算精度方面有很大的改进。 相似文献
18.
采用包含Davidson修正的多参考组态相互作用(MRCI+Q)方法结合6-311++G(3df,3pd)基组计算了LiC分子基态(X4Σ-)以及五个低电子激发态(a2Π,b2Δ,c2Σ-,d2Σ+,A4Π)的势能曲线.将得到的势能曲线拟合到Murrell-Sorbie解析势能函数形式,确定了对应态的平衡结构Re、谐振频率ωe和离解能De等光谱数据,计算值与仅有的几个其他结果进行了比较.通过求解核运动的薛定谔方程首次报道了LiC分子几个低电子态在J=0下的振动能级、转动惯量和六个离心畸变常数(Dν,Hν,Lν,Mν,Nν和Oν). 相似文献
19.
Potential energy curves(PECs) for the ground state(X 2 Σ +) and the four excited electronic states(A 2 Π,B 2 Π,C 2 Σ +,4 Π) of a BeH molecule are calculated using the multi-configuration reference single and double excited configuration interaction(MRCI) approach in combination with the aug-cc-pVTZ basis sets.The calculation covers the internuclear distance ranging from 0.07 nm to 0.70 nm,and the equilibrium bond length R e and the vertical excited energy T e are determined directly.It is evident that the X2Σ+,A2Π,B2Π,C2Σ+ states are bound and 4Π is a repulsive excited state.With the potentials,all of the vibrational levels and inertial rotation constants are predicted when the rotational quantum number J is set to be equal to zero(J = 0) by numerically solving the radial Schr¨odinger equation of nuclear motion.Then the spectroscopic data are obtained including the rotation coupling constant ω e,the anharmonic constant ωexe,the equilibrium rotation constant Be,and the vibration-rotation coupling constant αe.These values are compared with the theoretical and experimental results currently available,showing that they are in agreement with each other. 相似文献
20.
G. Kurizki 《辐射效应与固体损伤》2013,168(1):119-129
Abstract Recently, the possibility of obtaining ISE in spectral bands of forbidden light propagation (photonic bandgaps) has been suggested by Yablonovitch.1 These bandgaps are spectral regions admitting only complex wavevectors k (evanescent waves) in any direction, and boundecl by frequencies ωmax((min) at which the dispersion curve ω(k) becomes discontinuous. Because they are associated with definite k (band edges), such hndgaps are delocalized in space, i.e., they inhibit spontaneous emission independently of t.he spatial distribution of emitters in the system. The systems that have been proposed1 for the demonstration of bandgaps are dielectric superlattices that exhibit strong three-dimensional (3D) periodic moclulations of the dielectric index with a period comparable to half the emission wavelength. 相似文献