Optical Dephasing and Phonon Dynamics in Ordered Crystals, Disordered Crystals and Molecular Beam Epitaxy Films

有序晶体、无序晶体和分子束外延薄膜中的光学相移和声子动力学

• 批准号: 9321052
• 负责人: Richard Meltzer
• 金额: $ 22.5万
• 依托单位: University of Georgia Research Foundation Inc
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1994
• 资助国家: 美国
• 起止时间: 1994-02-15 至 1998-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9321052&HistoricalAwards=false
• 关键词: Optical; Dephasing; Phonon; Dynamics; Ordered; Optical; Dephasing; Phonon; Dynamics; Ordered

9321052 Meltzer The optical dephasing time of dopant ions will be used as a tool to investigate two-level systems (TLS) in disordered crystalline materials such as mixed solid solutions and polycrystalline films, where the disorder is generally experimentally variable. These types of experiments will be extended to ordered arrangements of atoms in a restricted geometry, such as MBE grown undoped as well as rare earth ion doped superlattices. In a second set of experiments phonon dynamics will be studied with a number of innovative approaches. These include use of a very short duration (100 ps) pulses to study phonon-phonon interactions in RE doped fluoride crystals, and use of two FIR pulse sources to study the interaction between two narrow band phonon populations. A third study will apply coherent and transient holeburning techniques to study the dynamics of the photoionization process of transition metal ion sites in ferrolectric materials. %%% Unique optical techniques will be applied to study the nature of disorder in doped crystals, mixed solid solutions, and ultrathin semiconductor layers. The unique techniques include two ultrashort pulsed lasers which emit radiation at very long infrared wavelengths used for directly generating sound waves in solids, and a special laser which emits visible light which is extremely close to a single frequency. The latter light source will allow to study changes in absorption induced by a laser very accurately as a function of light wavelength. A key aspect of this work is that the degreee of disorder can be experimentally varied when preparing a particular sample material. This study is expected to provide new sensitive tools for characterizing disorder with applications to more controlled growth of a variety of optoelectronic materials. ***

9321052 Meltzer掺杂剂离子的光学脱位时间将被用作研究中混合固体溶液和多晶膜等无序晶体材料中的两级系统（TLS）的工具，其中该疾病通常在实验上是可变的。 这些类型的实验将扩展到有限的几何形状中原子的有序排列，例如MBE生长的不耗尽以及稀土离子掺杂的超晶格。 在第二组实验中，将使用多种创新方法研究声子动力学。 其中包括使用非常短的持续时间（100 ps）脉冲来研究掺杂的氟化物晶体中的声子 - 音纸相互作用，以及使用两个FIR脉冲源来研究两个窄带声子种群之间的相互作用。 第三项研究将应用连贯和瞬态的孔燃料技术来研究铁晶材料中过渡金属离子位点的光电离过程的动力学。 %% %%独特的光学技术将用于研究掺杂晶体，混合固体溶液和超薄半导体层中疾病的性质。 独特的技术包括两种超短脉冲激光器，它们以非常长的红外波长发射辐射，用于直接在固体中产生声波，以及发出可见光的特殊激光器，它极接近单个频率。 后一种光源将允许非常准确地研究激光诱导的吸收变化，这是光波长的函数。 这项工作的一个关键方面是，准备特定样品材料时，疾病的脱发可以在实验上变化。 预计这项研究将提供新的敏感工具，用于表征障碍，并应用于各种光电材料的更具控制的生长。 ***