Theoretical Studies of Relaxation, Energy Transfer and Non-linear Spectroscopy in Molecular Systems

分子系统中弛豫、能量转移和非线性光谱的理论研究

• 批准号: 9617013
• 负责人: Robert Silbey
• 金额: --
• 依托单位: Massachusetts Institute of Technology
• 依托单位国家: 美国
• 项目类别: Continuing grant
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-05-01 至 2000-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9617013&HistoricalAwards=false
• 关键词: Theoretical; Studies; Relaxation; Energy; Transfer

The Theoretical and Computational Chemistry program is supporting Professor Silbey at MIT. During the next three years theoretical models will be developed for the study of several distinct areas. The first involves low temperature optical properties of molecules in condensed phases, in particular glassy solids. Spectral hole burning, photon echoes, and single molecule spectroscopy have all shown that the so called homogeneous line shape of a molecule is time dependent because of slow fluctuations in the condensed phase. These methods have different but often overlapping time scales, so that a complete picture of the time dependence from picoseconds to weeks can be found. The theoretical interpretations of these experiments based on a quantum statistical mechanical approach is the goal of the first area of research. The second involves optical and electronic properties of molecular aggregates in solutions. Molecular aggregates, such as the light harvesting complexes of the photosynthetic apparatus, have been under intense experimental study over the past decade. The advent of femtosecond lasers in the correct spectral range has led to new experiments studying the time dependence of excitation energy transfer and vibrational relaxation in these aggregates. The theoretical understanding of the electronic and vibronic states and the dynamics of energy flow of these aggregates is the central problem of this phase of the supported research. Because of experimental advances, second harmonic light scattering from molecules in solution has reemerged as an important tool to measure the non-linear optical properties of molecules. However, the interpretation of these experiments in terms of the molecular and solvent properties requires a modern theoretical basis, which is the goal of the third part of this grant. In particular, the description of the fluctuations of the solvent field at the solute molecule is essential to a correct interpretation of the experimental results. The optical spectrum of a molecule is a signature of its electronic structure and the environment in which the molecule finds itself. The effects of the environment can be profound and can make the identification and understanding of the optical properties of the molecule difficult. Thus, a study of these effects provides information not only on the molecular spectrum, but also on the environment. The purpose of this research is to understand theoretically the effects of the environment (solvent) on the optical properties of a molecule. The molecules that will be studied are organic molecules that have a large linear and non-linear optical response; these include: dye molecules used in laser research, chlorophyll and aggregates of chlorophyl (antenna complexes and reaction centers), and conjugated molecules that are candidates for use in optical switching and communication devices. The solvents or environments that the molecules are in include normal liquids, solids and glasses. The theoretical research will be carried out in collaboration with experimentalists who are measuring these optical properties.

理论和计算化学计划支持 麻省理工的西尔贝教授 在接下来的三年里，理论模型 将被开发用于几个不同领域的研究。 第一 涉及分子的低温光学性质， 相，特别是玻璃状固体。 光谱烧孔，光子 回波和单分子光谱都表明， 所谓的均匀线形状的分子是时间依赖的，因为 凝聚态的缓慢波动这些方法有不同的 但往往重叠的时间尺度，使一个完整的图片的时间 可以发现从皮秒到数周的依赖性。 基于量子统计的这些实验的解释 机械方法是第一个研究领域的目标。 的 二是分子聚集体的光学和电子性质 解决方案。 分子聚集体，例如光捕获 光合机构的复合体，一直处于强烈的 过去十年的实验研究。 飞秒的出现 在正确的光谱范围内的激光已经导致了新的实验研究 激发能转移和振动的时间依赖性 在这些聚集体中的松弛。 理论认识 电子态和振动态以及它们的能量流动力学 骨料是这一阶段的核心问题， research. 由于实验的进步，二次谐波光 溶液中分子的散射作为一种重要的工具 来测量分子的非线性光学特性。 但 根据分子和溶剂对这些实验的解释 这就需要一个现代的理论基础，这是我们的目标。 第三部分是这一补助金。 特别是， 溶质分子处的溶剂场的波动对于 对实验结果的正确解释。 一个分子的光谱是它的电子信号 结构和分子所处的环境 的 环境的影响可能是深远的，可以使 识别和理解的光学性质的 分子难。 因此，对这些影响的研究提供了 不仅在分子光谱上，而且在环境上。 的 本研究的目的是从理论上了解 环境（溶剂）对分子光学性质的影响。 的 将被研究的分子是有机分子， 线性和非线性光学响应;这些包括：使用的染料分子 在激光研究中，叶绿素和叶绿素聚集体（触角 络合物和反应中心），以及 用于光交换和通信设备的候选物。 的 所述分子所处的溶剂或环境包括正常的 液体、固体和玻璃。进行理论研究 与测量这些光学特性的实验家合作， 特性.