GaN基蓝光发光二极管峰值波长偏移的研究

通过对蓝光和红光发光二极管在直流和脉冲电流两种情况下进行变电流测试,对其峰值波长的偏移情况进行了深入的对比分析和研究,指出主要是热效应和极化效应两个因素造成蓝光LED的峰值波长发生偏移,并计算出热效应单独引起峰值波长偏移的温度系数为0.080 7nm/K,In0.2Ga0.8N/GaN发光二极管量子阱中的极化强度为3.765 0 MV/cm;分析还认为电流注入下多量子阱中栽流子分布不均匀也是影响器件峰值波长的一个因素,并计算得到去除极化影响后量子阱中的场强,验证了在电流注入下多量子阱中载流子分布不均匀的结论.     

催化裂化催化剂上污染重金属含量测定的XRF光谱分析方法的研究

介绍了用 X射线荧光光谱测定催化裂化平衡催化剂上污染重金属 Fe、Ni、V、Cu、Sb和 Ca含量的分析方法。考查了影响 Fe、Ni等元素测定的各种因素 ,提出以新鲜催化剂为配制标样的载体 ,较好地克服了元素间互相干扰的影响 ,减少基体效应 ,取得了 Fe、Ni等元素含量的准确结果。实验结果表明 ,XRF光谱法测定催化剂上污染重金属元素的含量是一种快速、准确、简便的分析方法     

对乙酰基偶氮氯膦与镧显色反应的研究及应用

研究了对乙酰基偶氮氯膦与镧的显色反应 ,在 0 .2 mol/L 盐酸介质中 ,有乙醇及吐温 - 80存在时 ,生成3∶ 1紫色络合物。 λmax=6 75 nm,ε=7.33× 1 0 4 L· mol- 1· cm- 1。采用双波长法 ,以 5 30 nm为参比波长 ,6 75 nm为测定波长 ,ε=9.2 0× 1 0 4 L· mol- 1· cm- 1 ,镧含量在 0— 37.5 μg/2 5 m L范围内符合比耳定律。本法用于电子工业钛酸镧烧结中游离氧化镧的测定 ,结果令人满意。     

Phenomenological Connection Between Hadronic Wavefunction and Its Radius

A picture for the hadronic structure is discussed based on previous work^[1]. The radius contributed from the valence Fock-state wavefunction (i.e., qq component) is calculated in ~ the light-cone framework. We propose a concept of the characteristic length λ to represent the contributions of higher Fock states to hadronic radii phenomenologically and calculate its value. Using an equivalence between the "intrinsic" radii of constituent quarks and the radii coming from higher Fock states we put forward a constraint on the hadronic wavefunctions of mesons. It is found that these wavefunctions lead to consistency between theories and experiments for D and B exclusive decays. We also give the radii for K, D and B mesons. The results show that the radius of K meson is in good agreement with experimental data.     

Polaronic States Incorporating Effects of Phonon Confinement in a Rectangular Quantum Well Wire

The electron self-energy due to the interaction of the electron with the LO-phonon incorporating effects of phonon confinement in a rectangular quan tum well wire has been calculated as a function of the size of the wire by the perturbative method within the framework of the effective mass approximation. The results show that in a very smaU wire the self-energy has a peak at the beginning and then increases gradually to the two-dimensional limit value as the wire expands in one direction while keeping fixed in the other direction. The peak values are about at the square cross sections. For larger wires, the self-energy increases monotonically without appearing peaks and approaches slowly to the two-dimensional limit values. The results also present that the self-energy is related to the size of the cross section rather than to the cross sectional area of the wire, and the absolute values of the self-energies are lese than those in comparable two-dimensional quantum wells.     

Anomalous Vector-Boson Mass Generation on a Lattice

We show the vector boson mass generation on a lattice with the Wilson's fermion formulation. By calculating explicitly the change of the effective action under chiral transformation, it is also found an arbitrariness in the solution of the chiral Schwinger model, which depends on a lattice regularization in continuum theory.     

Beltrami Gauge Symmetry and 2D Induced Gravity

We introduce the Beltrami gauge symmetry related to the Beltrami parametrization of the metrics and the Beltrami equations. We explore its role in 2d induced gravity and show that Polynkov's. SL(R) and KPZ's residual symmetries are subsymmetries of the Beltrami gnuge symmetry in the light-cone gauge. We also find that the 2d induced gravity with or without matter can be reformulated as Beltrami-Liouville field theories on Riemann surfaces of higher genus.     

Study on KC1 Colorated Center Doped with Na+ Crystal by Positron Annihilation

The relation of the live times and S parameters with doped quantities of Na⁺ have been studied by positron annihilation method in pure,colourable and irradiant KC1 single crystals,The results show that the concentration of vacancies of KC1 doped with 800ppm Na⁺ is 4.24×10¹⁷/cm³.It is close to that of the pure KC1 crystal.The obvious F centers exist in the colorated crystal.The S parameters are mainly influenced by the external electrons of halide ions.Mechanism of annihilation of KC1 crystal doped with Na⁺ has been discussed.     

Shallow States of Donor Impurities at Defective Semiconductor Surfaces

Ground state energies for shallow states of donor impurities at certain idealized defective isotropic semiconductor surfaces are calculated variationally for GaAa surfaces with electrons confined within the semiconductor. Calculations show that impurity states with donor ions located at parts projecting out of surfaces have lower ground state energiea than those with ions located at parts sunk into surfaces.     

Calculation of Binding Energies of the Ground and Excited States of a Donor in GaAs-A1xGal-xAs Step Quantum Wells

In this paper we present for the first time completely analytical variational expressions for calculating the binding energies of the low-lying bound states of a hydrogenic donor in a quantum well (QW). These expressions can be used for the problem of the binding energy of an impurity in a general manner, e.g. for calculating the binding energies of a donor associated with subband states of any order in the QW with any arbitrary potential profile. 70 demonstrate the utilization of these expressions we have theoretically studied the binding energies for the ground and a few low-lying excited etates of a hydrogenic donor in a stepped quantam well (SQW). The variations of the binding energies for these donor etates with impurity positions are investigated for different heights of the step potential. The numerical calculation results show that the binding-energy curves in the SQW, in contrast to the case of the flat quantum wells (FQW's), exhibit a non-symmetrical structure relative to the center of the QW and depend on the sub-barrier potential. The peak position in the binding energy curves shifts away from the region occupied by the sub-barrier as increasing sub-barrier height. The maximum in the binding energies increases as the step potential increaaes. These effects can be interpreted by referring to the variation of the electron probability-density distribution and of the lowest subband in the SQW. The shape of the binding-energy curves related to the 2po-like state is different from the other states. It is associated with the particular feature of the wave function of the 2po state in the QW.