一题渗透多向发散——上好复习课一例

复习课形式多种多样,各不相同,但是如何高效而紧凑地上好一堂复习课,帮助学生将前面在较长时间内所学知识澄清、巩固,掌握知识的本质联系,提高综合运用和熟练解题的技能,着重培训学生发散思维的能力。这些都大有研究和探讨的必要。当前,随着教学方法改革的深入,有一点是肯定的,就是大搞题海战术盲目     

Numerical studies of atomic three-step photoionization processes with non-monochromatic laser fields

The atomic selective multi-step photoionization process is a critical step in laser isotope separation. In this work, we study three-step photoionization processes with non-monochromatic laser fields theoretically based on the semi-classical theory. Firstly, three bandwidth models, including the chaotic field model, de-correlation model, and phase diffusion model, are introduced into the density matrix equations. The numerical results are compared with each other comprehensively. The phase diffusion model is selected for further simulations in terms of the correspondence degree to physical practice. Subsequently, numerical calculations are carried out to identify the influences of systematic parameters, including laser parameters (Rabi frequency, bandwidth, relative time delay, frequency detuning) and atomic Doppler broadening, on photoionization processes. In order to determine the optimal match among different systematic parameters, the ionization yield of resonant isotope, and selectivity factor are adopted as evaluation indexes to guide the design and optimization process. The results in this work can provide a rewarding reference for laser isotope separation.