用计算机模拟技术研究潜影形成的机理

用Monte Carlo计算机模拟技术研究了溴化银立方晶体中潜影形成的机理。根据潜影研究的一些重要实验结果,在设计模拟模型时作了以下基本假定:(1)光照产生的电子在离子步骤发生之前,很快就达到导带与浅陷阱两种状态的平衡,这里除了表面结点位和晶格位错位之外,填隙银离子也能起浅电子陷阱的作用;(2)Ag、Ag₂和Ag₃的形成(成核过程)为低效过程,而Ag₄⁺ 形成后的成长为高效过程;(3)光照产生的正空穴要经历“V”中心,溴原子和溴分子的演变过程,此时可能发生复合反应和回归反应。 模拟参数的估计是基于一些物理测量,如微波光导和介电损耗等的测量结果。模拟结果定量地展示了潜影形成过程中各种反应物,中间物和生成物的产生和变化,并与宏观的实验结果,如感光响应曲线和互易律失效曲线等,相当一致。

A STUDY ON THE MECHANISM OF LATENT IMAGE FORMATION BY COMPUTER SIMULATION TECHNIQUE

Monte Carlo computer simulation technique was used for studying the mechanism of latent image formation in cubic crystals of silver bromide. Based on some significant results from the researches on latent image,certain fundamental assumptions were made in this model as follows: 1) before the ionic step starts the electrons released by photons rapidly reach an equilibrium between electrons in conductance band and those in shallow traps,as which interstitial silver ions may act besides kink sites and dislocation jogs; 2) formations of Ag,Ag₂,and Ag₃ (nucleation) are inefficient,whereas the growth after the formation of Ag₄⁺ is efficient; 3) positive holes produced by photons will have an evolution from holes to Br2 through V-Centers and bromine atoms,and during the evolution recombination and regression may take place. The estimation of parameters for simulation is based on some physical measurements,such as by microwave technique and dielectric loss etc. The results from simulation quantitatively show the productions and the changes of various species,such as reactants,intermediates,and products,and also show a consistency with some of macroscopic experimental results,response curves and reciprocity curves as for instance.