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首页> 外文学位 >Ultrafast electronic relaxation processes in semiconductor nanoparticles (silver iodide, silver iodide/silver sulfide, silver bromide/silver sulfide, silver sulfide, cupric sulfide, and copper sulfide) and carotenoids.
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Ultrafast electronic relaxation processes in semiconductor nanoparticles (silver iodide, silver iodide/silver sulfide, silver bromide/silver sulfide, silver sulfide, cupric sulfide, and copper sulfide) and carotenoids.

机译：半导体纳米粒子（碘化银，碘化银/硫化银，溴化银/硫化银，硫化银，硫化铜和硫化铜）和类胡萝卜素中的超快电子弛豫过程。

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摘要

This dissertation examines primarily the ultrafast dynamics of excited state charge carriers in semiconductor nanoparticles. The dissertation also briefly examines the excited state lifetimes of a few carotenoids. Understanding the dynamic properties of charge carriers in semiconductor nanoparticles is crucial for the further development of applications utilizing these systems. The dynamic properties including shallow and deep trapping as well as recombination have been studied in a variety of semiconductor nanoparticle systems. Kinetic modeling was utilized to assist in the assignment of all observed signals and the nature of the decays. The first observation of ultrafast trapping in silver halides was observed in AgI nanoparticles including the identification that interstitial silver ions may act as deep traps. Several interesting phenomena were observed in Ag2S and CuxS nanoparticles including dark shallow trap states and shallow trap state saturation leading to increased transient absorption over transient bleach with increasing excitation intensity. These observations have provided further insight into the relaxation pathways for charge carriers in semiconductor nanoparticle systems. Lifetimes of the S2 excited states of four carotenoids have also been determined. The S2 lifetime for beta-carotene was confirmed from previous fluorescence up-conversion experiments whereas the S2 lifetimes that were previously unknown for three carotenoids, violaxanthin, neaxanthin, and lutein were discovered. These experiments together demonstrate the capabilities of femtosecond pump-probe spectroscopy to characterize and better understand the processes involved in the ultrafast relaxation events in both molecular and nanoparticle systems.
机译：本文主要研究了半导体纳米粒子中激发态电荷载流子的超快动力学。本文还简要考察了几种类胡萝卜素的激发态寿命。了解半导体纳米粒子中载流子的动态特性对于利用这些系统的应用程序的进一步开发至关重要。在各种半导体纳米粒子系统中，已经研究了包括浅陷和深陷以及重组在内的动力学特性。动力学建模被用来协助分配所有观察到的信号和衰减的性质。在AgI纳米颗粒中首次观察到卤化银超快捕获的结果，包括确定间隙银离子可能充当深陷阱。在Ag2S和CuxS纳米粒子中观察到了一些有趣的现象，包括暗的浅陷阱态和浅陷阱态饱和，导致随着激发强度的增加，瞬态漂白剂的瞬态吸收增加。这些观察为半导体纳米粒子系统中电荷载流子的弛豫途径提供了进一步的见解。还确定了四个类胡萝卜素的S2激发态的寿命。 β-胡萝卜素的S2寿命可以通过先前的荧光上转换实验得到确认，而发现了三个类胡萝卜素，紫黄质，neaxanthin和叶黄素以前未知的S2寿命。这些实验共同证明了飞秒泵浦探针光谱法能够表征和更好地理解分子和纳米粒子系统中超快弛豫事件所涉及的过程。

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  • 作者

    Brelle, Michael Chris.;

  • 作者单位

    University of California, Santa Cruz.;

  • 授予单位 University of California, Santa Cruz.;
  • 学科 Chemistry Physical.; Physics Condensed Matter.
  • 学位 Ph.D.
  • 年度 2000
  • 页码 193 p.
  • 总页数 193
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 物理化学（理论化学）、化学物理学;
  • 关键词

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