TIME RESOLVED XAFS & OPTICAL MONITORING

本项目涉及制造一个停流装置， 时间分辨XAFS实验。 我们构建了一个紧凑的 用于BioCAT光束线的停流装置。 两个驱动 注射器和止动注射器嵌入支撑架中， 结构和热稳定性。 电磁阀连接到 具有快速响应时间的注射器。 伯杰搅拌球， 其具有4ml的混合体积 保持器以进一步限制死体积。 的总体积 样品保持器为70 ml。 该系统是封闭在一个罩与聚酯薄膜 Windows. 温度是通过调节冷量来控制的 氮气\氦气进入系统，带式加热器电流开启 支撑框架。 试验表明，温度可以控制 在几个小时内保持在几度之内。 自动驾驶系统 是设计和制造的。 伺服电机用于提供 准确和快速的重复样品交付。 分离的马达 用于止动注射器和驱动注射器的驱动器可以满足这些要求 满足不同的混合要求，但又能适应不同的混合比例。 将使用PC控制注射器的驱动和停止， 电磁阀 初步测试的停止流正在进行中。 一 该装置的先决条件之一是其金属含量低 污染. 发现系统的杂质是等效的 至50 mM的Fe和Zn边缘。 停流性能将 首先使用简单的金属离子反应进行测试，例如混合 氰化物和抗坏血酸在低pH值。该系统也将进行测试 用于生物反应。

This project deals with fabrication of a stopped-flow device for time-resolved XAFS experiments. We have constructed a compact stopped-flow device for use at the BioCAT beamline. Two drive syringes and a stop syringe are embedded in a support frame for structural and thermal stability. Solenoid valves are connected to the syringes which have a fast response time. A Berger ball mixer, which has a mixing volume of 4 ml is directly mounted on the sample holder to further limit the dead volume. The total volume of the sample holder is 70 ml. The system is enclosed in a shroud with mylar windows. The temperature is controlled by regulating the flow of cold nitrogen\helium gas into the system and the current of tape-heaters on the supporting frame. Test shows that temperature can be controlled within a few degrees for several hours. Automated driving systems were designed and fabricated. Servo-motors are used to provide an accurate and fast repetitive sample delivery. The separate motor drives for the stop syringe and driving syringes can satisfy these requirements and yet are versatile for different mixing proportions. A PC will be used to control the drive and stop syringes, and the solenoid valves. Initial tests of the stopped-flow are underway. One of the prerequisites of the device is its low level of metal contamination. The impurity of the system is found to be equivalent to 50 mM at Fe and Zn edges. The performance of the stopped-flow will be tested first using a simple metal ion reaction, such as the mixing of cyanide and ascorbate at low pH. The system will also be tested for biological reactions.