【作者】 李莉；

【导师】 李晓苇；

【作者基本信息】 河北大学 ， 光学， 2007， 硕士

【摘要】 电子陷阱是表征晶体材料结构不完整性的重要参数之一,研究外界引入的染料对微晶电子陷阱的影响,对于了解晶体结构以及探索晶体材料表面改性等问题都有着重要的意义。本工作以立方体氯化银微晶为研究对象,利用微波吸收介电谱检测技术系统的测量了不同增感条件下氯化银乳剂在355ns激光波长曝光下所产生的光电子衰减行为,并结合光电子衰减的动力学理论对染料吸附造成的氯化银微晶中电子陷阱的改变进行了研究。在分析了具体的实验条件和氯化银微晶光电子衰减曲线特征的基础上,根据卤化银的基本模型,建立了本工作所用氯化银乳剂的具体模型和动力学方程,并讨论了模型中各陷阱对光电子整体衰减行为的影响。结果发现,微晶表面深电子陷阱对光电子衰减的影响显著。利用微波吸收介电谱检测装置对不同增感浓度和不同增感时间条件下的氯化银乳剂进行了测量,发现：在染料的增感浓度较低的情况下,光电子的衰减会随着增感浓度和增感时间的增大先减慢后加快,而当染料的增感浓度较高时,光电子的衰减会随着增感浓度和增感时间的增大先加快后略微减慢。这说明,不同吸附状态下的染料对微晶造成了不同的影响,并且,增感时间对微晶结构造成的影响,从本质上可以归结为染料吸附量的变化对微晶结构的影响。应用光电子衰减的动力学关系对以上出现的实验现象进行理论分析,结果发现,增感浓度对光电子衰减的影响是通过改变染料在微晶表面的吸附量以影响微晶表面的电子陷阱来完成的。并且单分子态吸附的染料对氯化银微晶表面的陷阱能级具有修饰作用,这使得深电子陷阱减少,光电子衰减变慢。而以聚集态吸附的染料可以使氯化银微晶表面隙间银离子增多,导致光电子衰减加快。这两种作用会随着增感浓度的变化逐步演变交替出现：当增感浓度从0开始逐渐增大时,首先起效的是染料分子对微晶的修饰作用,随着增感浓度达到一定量时,染料开始出现聚集,银离子析出作用出现并增强,同时,修饰作用减弱,当染料足够多使得银离子完全析出时,此作用也达到了最强,继续加大增感浓度,修饰作用又凸现出来。通过检测不同增感浓度下的光电子衰减曲线并利用光电子衰减的动力学关系对微晶中电子陷阱进行定量化分析,可以得到具体条件下的银离子析出以及完全析出时对应的染料的增感浓度。更多还原

【Abstract】 Electron trap is one of the most important physical properties of crystal materials in the course of disintegrality,and the study of effect of dye adsorption on electron traps is helpful for learning about the materials’configuration and exploreing the matter of surface mend of cry stall.The photoelectron decay curves of different spectral sensitized cubic silver chloride which are exposed by the light 355ns wavelength are measured by microwave absorption and dielectric spectrum detection technology. Combining with photoelectron decay kinetics,the effect of dye adsorption on the structure of silver halide microcrystals is studied in this work.At first,based on the analysis of the photoelectron decay curves specifically experimental conditions and basic dynamic model of silver halide,the specifically dynamic model and equations are built up,and the influences of various traps on photoelectron decay are discussed. It is found that the effect of deep electron traps in the surface of microcrystal on the photoelectron decay is prominence.Then, The photoelectron decay curves of cubic silver chloride on different sensitization condition are measured by microwave absorption and dielectric spectrum detection technology.It is found that when the sensitization concentration is lower,with the sensitization concentration increasing and the sensitization time prolonging,photoelectron decay of sensitized emulsion become first slower,then faster,however,when the sensitization concentration is higher, with the sensitization concentration increasing and the sensitization time prolonging,photoelectron decay of sensitized emulsion become first faster,then slower.This result shows that the influence of dye adsorbent in the different condition on the microcrystal is different,and the influence of sensitization time to the structure of microcrystal can come down to the influence of sensitization concentration to the microcrystal in substance.Then using the photoelectron decay kineties,the experimental results are explained from the aspect of theory.The result shows that the influence of sensitization concentration on the decay of photoelectron is achieved by the change of electron traps in the surface of silver halide,besides,when the dye sdsorbed in silver chloride is sepatated,it makes the deep electron traps in the surface of microcrystals decrease by decorating the energy level of microcrystals,and when the dye adsorbed is congregated,it makes the deep electron traps in the surface of microcrystals increase by increasing the Agi+ in microcrystals.This two actions can evolvement along with the change of sensitization concentration,that is when the sensitization concentration is increase from O,the action of decorate appears firstly and increases with the increasing of sensitization concentration;when the dye adsorbed in silver chloride reaches a certain extent,the action of separate out of Agi+ appears and increases with the increasing of sensitization concentration,at the same time,the action of decorate decreases;when the sensitization concentration reaches a enough high extent so as to the Agi+ are separate out completely,the action of separate out of Agi+ reaches the most and the action of decorate increasing again with the sensitization concentration’s maintain increase.Through the detection of the photoelectron decay curves of cubic silver chloride in different sensitization concentration conditions and using photoelectron decay kinetics,the quantificational analyse to the electron traps in microcrystals can be achieved,besides,the sensitization concentrations corresponding to the separate out of Agi+ and separate out completely can be gained in the specifically experimental conditions.更多还原