Development of Instrumentation for Photochemical Studies

光化学研究仪器的发展

• 批准号: 6535092
• 负责人: COLIN CHIGNELL
• 金额: --
• 依托单位: NATIONAL INSTITUTE OF ENVIRONMENTAL HEALTH SCIENCES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/6535092
• 关键词: biomedical equipment development; computer program /software; electrical measurement; electromagnetic radiation; electron spin resonance spectroscopy; environmental toxicology; flash photolysis; fluorescence spectrometry; infrared spectrometry; laser spectrometry; photochemistry; photoconduction; photoelectron spectrometry; singlet oxygen; spectrometry; spectrophosphorimetry

Spectral techniques such as fluorescence, phosphorescence, flash photolysis, and ESR are necessary to elucidate the photophysics and photochemistry of environmental chemicals. Because much of the needed equipment is either not available commercially or does not offer the desired features, we build or modernize/upgrade most of it ourselves. This includes the interfacing to computers for ease of data acquisition and manipulation. Two old spectrophotofluorometers (steady state and phase modulation) that have been combined into one T-configured unit have being upgraded to measure phosphorescence spectra and photobleaching. The laser flash photolysis set-up has a new more powerful laser (Surelite II) for excitation. The choice of excitation wavelengths has been extended from 400nm to the infrared by using a tunable OPO system that is pumped by the 355nm harmonic from the Surelite laser. A flow system that refreshes anaerobic samples after strong laser excitation has been added to prevent the bleaching of the irradiated area. This new laser flash photolysis set-up has been adapted for EMF studies by incorporating an electromagnet and a new analytical lamp to observe the transient spectra in the presence of EMF. The Surelite laser has also been aligned with the EPR spectrometer to generate radicals directly in the cavity of the EPR spectrometer after multi-photon absorption from laser pulses. Our singlet oxygen spectrometers are being presently used to measure the interaction of singlet molecular oxygen with biological and environmental substrates we investigate. In addition, the steady-state singlet oxygen spectrophotometer is being upgraded to measure singlet oxygen production in non-photochemical reactions. This system has also been modified to permit the direct observation of keratinocytes grown in a monolayer. With the aid of this instrumentation we have been able for the first time to detect singlet oxygen directly in cells. To interpret the singlet oxygen phosphorescence data correctly, we have to establish how singlet oxygen properties may be affected by different environment. We have already measured the influence of polarity, proticity and polarizability in a number of solvents and solvent mixtures. Presently, these investigations are being extended over the heterogeneous (micellar) systems, which more closely relates to biological environments. As new technology becomes available, all of the above systems are continually being modified. These changes frequently also require the building of new interfaces and the development of new software for control. We are presently building a prototype photoconductivity cell to measure electrical photoconductivity in dielectric liquids in conjunction with ESR detection. This cell will be interfaced to the time-resolved laser flash photolysis spectrometer (vide supra) to permit studies of systems that cannot be observed optically. The laser flash photolysis system has been upgraded with a tunable laser system which emulates dye lasers. This new system has been adapted for EMF studies by incorporating an electromagnet. We are modifying our infrared spectrometer to study cells and tissues. In order to understand the photochemistry and photophysics of environmental chemicals it is necessary to use the techniques of modern chemical analysis including spectroscopic techniques of many kinds. The object of this project is to build, test and interface spectrometers that are needed for photophysical studies.

荧光，磷光，闪光分解和ESR等光谱技术对于阐明环境化学物质的光体物理学和光化学是必要的。由于许多所需的设备要么无法商业上可用，要么没有提供所需的功能，因此我们自己建造或现代化/升级了大部分。这包括与计算机的接口，以易于数据采集和操纵。将两个旧的分光光荧光计（稳态和相位调制）组合成一个T配置单元已升级以测量磷光光谱和光漂白。激光闪光光解设置具有一种新的功能更强大的激光（Surelite II）进行激发。通过使用Surelite激光器355nm谐波泵送的可调OPO系统，将激发波长的选择从400nm扩展到红外。添加了强烈激励激发后刷新厌氧样品的流动系统，以防止被辐照区域的漂白。这种新的激光闪光光解设置已通过合并电磁体和新的分析灯来调整EMF研究，以观察EMF存在的瞬态光谱。 Surelite激光器还与EPR光谱仪对齐，以在激光脉冲吸收多光子吸收后直接在EPR光谱仪的空腔中产生自由基。目前，我们的单线氧光谱仪用于测量单线分子氧与我们研究的生物学和环境底物的相互作用。此外，升级的稳态单线分光光度计正在升级，以测量非光化学反应中的单线氧的产生。该系统还经过修改，以允许直接观察单层中生长的角质形成细胞。借助这种仪器，我们首次能够直接在细胞中检测单线氧。为了正确解释单线氧磷光数据，我们必须确定单线氧特性如何受到不同环境的影响。我们已经测量了许多溶剂和溶剂混合物中极性，原质和极化性的影响。目前，这些研究正在扩展到异质（胶束）系统，该系统与生物环境更加紧密相关。随着新技术的可用，上述所有系统都在不断修改。这些更改经常还需要建立新的接口和开发新软件以进行控制。我们目前正在构建一个原型光电导率细胞，以测量电介质液体中的电导性和ESR检测。该单元将与时间分辨激光闪光光解光谱仪（VIDE SOPRA）连接，以允许研究无法通过光学观察到的系统。激光闪光光解系统已通过模拟染料激光器的可调激光系统升级。该新系统已通过合并电磁体来适应EMF研究。我们正在修改红外光谱仪以研究细胞和组织。为了了解环境化学物质的光化学和光体物理学，有必要使用现代化学分析的技术，包括多种光谱技术。该项目的目的是构建，测试和界面光谱仪，这些光谱仪是光物理研究所需的。