论文部分内容阅读
用于研究物质结构的光电子全息 ,其物理机制是光电子波在固体中的散射。在电子能量为 5 0～ 2 0 0eV的中低能量下 ,不能用通常的平面波近似方法加以研究 ,必须考虑到光电子波的球面波本质。即使在电子能量大于 5 0 0eV的高能情况下 ,用平面波近似的方法也应对前向散射进行修正。本文以铜单晶薄膜为例 ,利用单重散射模型讨论了球面波近似模型下校正因子对光电子全息函数的影响 ,并与平面波近似作了比较。结果表明 ,对能量低于 2 0 0eV的光电子全息来说 ,球面波近似校正因子对前向散射和背向散射的振幅和相位都有较明显的修正。而在高能条件下 ,球面波近似校正因子主要影响光电子的前向散射 ,对背向散射的影响较小。进一步研究发现 ,球面波近似校正可以提高光电子全息的重现图的质量。
The physical mechanism of photoelectron holography, which is used to study the physical structure, is the scattering of photoelectrons in solids. At low and medium energies of 50 ~ 200eV, the normal plane wave approximation method can not be used to study the spherical wave nature of the photoelectron wave. Even in the case of high-energy electron energies greater than 500eV, the forward scattering should be corrected by the method of plane wave approximation. Taking the single crystal copper film as an example, the influence of the correction factor on the optoelectronic holographic function under the spherical wave approximation model is discussed by using the single-scattering model and compared with the plane wave approximation. The results show that for the photoelectron holograms with energies less than 200eV, the spherical wave approximation correction factor has obvious correction to the amplitude and phase of forward scattering and backscattering. Under high energy conditions, the approximate spherical wave correction factor mainly affects the forward scattering of photoelectrons and has little effect on backscattering. Further studies have found that the spherical wave approximation correction can improve the quality of the reproduced images of photoelectron holography.