TIME RESOLVED XAFS & OPTICAL MONITORING

这个项目涉及到制造一种可供选择的止流装置 时间分辨XAFS实验。我们已经建造了一个紧凑的 用于BioCAT光束线的停流装置。两个驱动器 注射器和止动注射器嵌入在支撑框架中以 结构和热稳定性。电磁阀连接到 反应时间快的注射器。伯杰球类搅拌机， 其混合体积为4毫升，直接安装在样品上 持有者进一步限制死体积。总成交量 样品盒为70毫升。系统用聚乳酸包裹在裹尸布中 窗户。温度是通过调节冷水的流量来控制的。 进入系统的氮氦气体和带式加热器的电流 支撑架。试验表明，温度是可控的 在几度之内持续几个小时。自动驾驶系统 都是设计和制造的。伺服电机被用来提供一种 准确快速的重复送样。分体式电机 止动注射器和驱动注射器的驱动装置可以满足这些要求 对于不同的混合比例，其要求和用途是多种多样的。 将使用PC来控制驱动器和停止注射器，以及 电磁阀。对停流的初步测试正在进行中。一 该装置的先决条件之一是其低水平的金属 污染。发现系统的杂质是等价的。 到50毫米在铁和锌的边缘。停止流动的性能将 首先使用简单的金属离子反应进行测试，例如混合 低pH值下的氰化物和抗坏血酸。该系统还将进行测试 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.