光的成因研究与分析

文章以所学的原子物理学和电磁物理学原理做基础,分析了原子核结构及其电场作用的特点,推证了物质电场的存在,再通过对电子旋转电场的进一步研究,找到了物质电场与旋转电场之间的联系。从而建立了"电子的旋转电场以物质电场为载体并与物质电场叠加传播形成光波的数理模型"。

Electronic and Shallow Impurity States in Semiconductor Heterostructures Under an Applied Electric Field

With the use of variational method to solve the effective mass equation, we have studied the electronic and shallow impurity states in semiconductor heterostructures under an applied electric field. The electron energy levels are calculated exactly and the impurity binding energies are calculated with the variational approach. It is found that the behaviors of electronic and shallow impurity states in heterostructures under an applied electric field are analogous to that of quantum wells. Our results show that with the increasing strength of electric field, the electron confinement energies increase, and the impurity binding energy increases also when the impurity is on the surface, while the impurity binding energy increases at first, to a peak value, then decreases to a value which is related to the impurity position when the impurity is away from the surface. In the absence of electric field, the result tends to the Levine's ground state energy (-1/4 effective Rydberg) when the impurity is on the surface, and the ground impurity binding energy tends to that in the bulk when the impurity is far away from the surface. The dependence of the impurity binding energy on the impurity position for different electric field is also discussed.

Anti-flooding of polymer electrolyte membrane fuel cell with in-plate adverse-flow flow-field

The stoichiometric ratios and related regimes, which can promote anti-flooding of polymer electrolyte membrane fuel cell （PEMFC） with in-plate adverse-flow flow-field （IPAF）, were investigated. Two flow combinations, which are the simple and complex adverse-flow between plates （ABP） that can be realized by IPAF, were employed. Constant stoichiometric ratios examination indicates that the complex ABP could improve anti-flooding of PEMFC better in the medium （greater than 200 mA/cm2 and less than 1 000 mA/cm2） and high （greater than 1 000 mA/cm2） current densities than the simple ABP. More stoichiometric ratios were introduced to find the cathode critical stoichiometry. Under the condition of cathode critical stoichiometry, the maximal local relative humidity of both electrodes of complex ABP is equal to 100% and below while the anti-flooding of the cathode of simple ABP is not satisfactory in the medium and high current densities. Further study shows that the mechanism of fuel cell, which is the imerdependence between the electrodes effect, can make significant contribution to anti-flooding.

Simultaneous Effects of External Electric Field and Conduction Band Nonparabolicity on Optical Properties of a GaAs Quantum Dot Embedded at the Center of a GaAlAs Nano-Wire

An investigation of the optical properties of a GaAs spherical quantum dot which is located at the center of a Ga1-xAlx As cylindrical nano-wire has been performed in the presence of an external electric field. The band nonparabolieity effect is also considered using the energy dependent effective mass approximation. The energy eigenvalues and corresponding wave functions are calculated by finite difference approximation and the reliability of calculated wave functions is checked by computing orthogonality. Using computed energy eigenvalues and wave functions, the linear, third-order nonlinear and total optical absorption coefficients and refractive index changes are examined in detail. It is found that （i） Presence of electric field causes both blue and red shifts in absorption spectrum; （ii） The absorption coefficients shift toward lower energies by taking into account the conduction band nonparabolicity; （iii） For large values of electric field the effect of conduction band nonparabolieity is less dominant and parabolic band is estimated correctly; （iv） In the presence of electric field and conduction band nonparabolicity the nonlinear term of absorption coefficient rapidly increases by increasing incident optical intensity. In other words, the saturation in optical spectrum occurs at lower incident optical intensities.