Development of Transient Infrared Spectroscopy

瞬态红外光谱学的发展

• 批准号: 9803006
• 负责人: Douglas Neckers
• 金额: $ 9.98万
• 依托单位: Bowling Green State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-09-01 至 2000-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9803006&HistoricalAwards=false
• 关键词: Development; Transient; Infrared; Spectroscopy

9803006NeckersThis award provides partial support for the development of a transient infrared spectrometer. Radiation-induced macromolecular synthesis and modification is critical to many technologies, ranging from combinatorial processes that involve site specific, chromophore-induced polymer photodegradation as the activating step to imaging, lithography, stereolithography, and a variety of rapidly drying printing/coating systems. Understanding the mechanisms of energy and electron transfer occurring in macromolecular assemblies is an important component of this work, as virtually every type of photoinduced reaction involves either energy transfer or electron transfer as an elementary step. The ability to monitor the kinetics of such processes is necessary to understand, and control, chemical events in materials ranging from polypeptide assemblies to photoactivated synthetic drugs. This project includes ongoing collaborations involving two senior faculty who, respectively, carry on broad programs in polymer photochemistry, stereolithography and three dimensional imaging, and on photoprocess dynamics, as well as a program focussing on studying electron transfer processes in rationally synthesized polypeptide assemblies. The instrumentation will be used to study photoinduced processes by monitoring the appearance and /or disappearance of infrared absoptions within the sub-microsecond time domain. In general, the instrument will employ laser flash photolysis to produce reactive intermediates in small molecules and films of macromolecules, and will use infrared absorption spectroscopy for their kinetic analysis. When constructed, the instrument will allow mechanistic studies to be conducted of the initiation steps of polymer photodegradation processes in real time, and provide direct assessment of the chemical reactions leading to changes in polymer properties. The instrument will also be used to analyze photoinitiator systems, to develop new reactive functionalities for the modification of polymer thin films, and to develop new imaging methodology. Other uses include the study of proton coupled electron transfer (PCET) reactions which play an important role in biological energy conversion, but whose mechnisms remain poorly understood. These studies will examine the role of a hyrogen-bonded peptide interface in controlling the rates of photoinduced electron-transfer in synthetic proteins by monitoring the kinetic response of the IR signals occurring within the amide I (1630 - 1700 cm-1) and amide II (1510 - 1560 cm-1) regions of the spectrum. Finally, the instrument will be used to study the photoinduced dissociation of NO from Fe(II) and Co(II) porphyrins. In these experiments, the amount of M-NO bond breaking leading to free NO production can be monitored by the loss of intensity of the M-NO absorption in the 5.87-6.55 um (1525-1690 cm-1) region (metal-dependent) and the growth of intensity at the NO bond stretching frequency 5.37um (1860 cm-1).In summary, the instrument will, as appropriate, be used to instantaneously evaluate the properties of formed chemical species, improve strategies to site isolate reactive entities as they are formed, understand polymer photodegration, and examine the kinetics of a variety of photoinitiated events. The constructed instrument will be tested using newly synthesized polymer systems such as styrenes, polyesters and other polymers containing chromophores for which the photochemistry has been studied in detail in solution.%%%***

9803006 Neckers该奖项为瞬态红外光谱仪的开发提供了部分支持。 辐射诱导的大分子合成和改性对许多技术是至关重要的，从涉及位点特异性的发色团诱导的聚合物光降解作为活化步骤的组合工艺到成像、光刻、立体光刻和各种快速干燥的印刷/涂布系统。 理解大分子组装中发生的能量和电子转移机制是这项工作的重要组成部分，因为几乎每种类型的光诱导反应都涉及能量转移或电子转移作为基本步骤。 监测这些过程的动力学的能力对于理解和控制从多肽组装到光活化合成药物的材料中的化学事件是必要的。 该项目包括正在进行的合作，涉及两名高级教师，他们分别进行聚合物光化学，立体光刻和三维成像，光过程动力学的广泛计划，以及一个专注于研究合理合成多肽组装中电子转移过程的计划。 该仪器将被用来研究光诱导的过程中，通过监测的外观和/或消失的红外吸收在亚微秒时域。 一般来说，该仪器将采用激光闪光光解来产生小分子和大分子膜中的活性中间体，并将使用红外吸收光谱进行动力学分析。 当构建时，该仪器将允许在真实的时间内对聚合物光降解过程的起始步骤进行机械研究，并提供导致聚合物性质变化的化学反应的直接评估。 该仪器还将用于分析光引发剂系统，开发用于聚合物薄膜改性的新反应官能团，并开发新的成像方法。 其他用途包括研究质子耦合电子转移（PCET）反应，该反应在生物能量转换中起着重要作用，但其机制仍然知之甚少。 这些研究将通过监测光谱的酰胺I（1630 - 1700 cm-1）和酰胺II（1510 - 1560 cm-1）区域内发生的IR信号的动力学响应来检查氢键键合的肽界面在控制合成蛋白质中的光诱导电子转移速率中的作用。 最后，该仪器将被用来研究NO从Fe（II）和Co（II）卟啉的光诱导解离。 在这些实验中，导致游离NO产生的M-NO键断裂的量可以通过在5.87-6.55 μ m波长处M-NO吸收强度的损失来监测。（1525-1690 cm-1）区域在NO键伸缩频率为5.37 μ m处，总之，该仪器将酌情用于即时评估所形成的化学物质的性质，改进策略以在反应性实体形成时对其进行位置隔离，了解聚合物光降解，并检查各种光引发事件的动力学。 将使用新合成的聚合物系统（如苯乙烯、聚酯和其他含有发色团的聚合物）测试所构建的仪器，已在溶液中详细研究了这些聚合物的光化学。