發(fā)布時(shí)間：2018-01-20 16:21

  本文關(guān)鍵詞： 上海光源 快速掃描X射線吸收精細(xì)結(jié)構(gòu) 雙晶單色器 實(shí)驗(yàn)物理與工業(yè)控制系統(tǒng) 數(shù)據(jù)采集系統(tǒng)　出處：《中國科學(xué)院研究生院（上海應(yīng)用物理研究所）》2015年博士論文　論文類型：學(xué)位論文

【摘要】：隨著同步輻射光源的出現(xiàn)和發(fā)展，各種新的同步輻射實(shí)驗(yàn)方法不斷涌現(xiàn)。發(fā)展新的同步輻射實(shí)驗(yàn)方法并利用它們開展對(duì)相關(guān)領(lǐng)域科學(xué)問題的研究已經(jīng)成為同步輻射光源應(yīng)用領(lǐng)域的一項(xiàng)重要內(nèi)容。X射線吸收精細(xì)結(jié)構(gòu)譜（X-ray Absorption Fine Structure，XAFS）是一種隨著同步輻射光源的發(fā)展而逐漸成熟起來的強(qiáng)有力的結(jié)構(gòu)分析方法。 不同于普通XAFS實(shí)驗(yàn)方法所采用的“step-by-step”模式的數(shù)據(jù)采集方式，快速掃描X射線吸收精細(xì)結(jié)構(gòu)譜（Quick-scanning X-rayAbsorption Fine Structure，QXAFS）實(shí)驗(yàn)方法采用“on-the-fly”的數(shù)據(jù)采集方式，能夠在雙晶單色器（Double Crystal Monochromator，DCM）連續(xù)運(yùn)動(dòng)的過程中獲取實(shí)驗(yàn)樣品的QXAFS譜。QXAFS實(shí)驗(yàn)方法可以在秒量級(jí)完成一個(gè)XAFS譜的數(shù)據(jù)采集工作，適合開展對(duì)催化工業(yè)、化學(xué)過程、生物傳感和材料科學(xué)等領(lǐng)域的動(dòng)態(tài)原位過程的研究。與能量色散XAFS（Energy-Dispersive X-rayAbsorption Fine Structure，EDXAFS）、泵浦-探測XAFS（pump-probe X-ray Absorption Fine Structure）等時(shí)間分辨的XAFS實(shí)驗(yàn)方法相比，該方法不需要更改光束線站的現(xiàn)有結(jié)構(gòu)，能夠與實(shí)現(xiàn)普通XAFS實(shí)驗(yàn)方法的光束線站兼容，特別適合上海光源XAFS光束線開展時(shí)間分辨XAFS實(shí)驗(yàn)方法的研究。 論文在廣泛調(diào)研了國內(nèi)外相關(guān)光束線站QXAFS數(shù)據(jù)采集系統(tǒng)的基礎(chǔ)上，開展了基于EPICS運(yùn)行平臺(tái)的運(yùn)動(dòng)控制和QXAFS數(shù)據(jù)采集系統(tǒng)的相關(guān)研究，主要包括以下工作： 1.針對(duì)上海光源XAFS光束線站現(xiàn)有的QXAFS數(shù)據(jù)采集系統(tǒng)的不足之處，完成了運(yùn)動(dòng)控制和QXAFS數(shù)據(jù)采集系統(tǒng)基于統(tǒng)一的運(yùn)行平臺(tái)的整體設(shè)計(jì)方案。在系統(tǒng)方案中，Scaler用于對(duì)高穩(wěn)定運(yùn)行的Bragg電機(jī)的控制脈沖的進(jìn)行計(jì)數(shù)以獲得單色光能量，高速ADC用于獲取樣品前后電離室的光電流信號(hào)，獨(dú)立運(yùn)行的硬件觸發(fā)信號(hào)源則為兩者分別提供1MHz的硬件觸發(fā)信號(hào)用于實(shí)現(xiàn)控制與數(shù)據(jù)采集系統(tǒng)的硬件同步。在實(shí)驗(yàn)室分別完成了三個(gè)部分的硬件配置、軟件開發(fā)和離線調(diào)試并對(duì)整體軟硬件系統(tǒng)進(jìn)行了集成和聯(lián)調(diào)。 2.在上海光源XAFS光束線站開展了基于EPICS的QXAFS數(shù)據(jù)采集系統(tǒng)的研究和測試。研究測試了提高QXAFS實(shí)驗(yàn)方法信噪比的相關(guān)實(shí)驗(yàn)條件，包括選擇ADC采樣率、確定Bragg電機(jī)驅(qū)動(dòng)器細(xì)分?jǐn)?shù)，在能量掃描過程中進(jìn)行T2電機(jī)補(bǔ)償；測試了電流放大器的配置參數(shù)對(duì)QXAFS譜的影響以及不同積分時(shí)間對(duì)QXAFS譜在高k區(qū)的平滑性的影響。經(jīng)過與標(biāo)準(zhǔn)的7.5um的標(biāo)準(zhǔn)銅箔樣品的普通XAFS譜相對(duì)比，證明了基于EPICS的QXAFS數(shù)據(jù)采集系統(tǒng)不僅采集速度快、采集到的QXAFS譜的信噪比好，而且整個(gè)系統(tǒng)具有很高的穩(wěn)定性和可重復(fù)性。 應(yīng)用該系統(tǒng)在上海光源XAFS光束線站開展了對(duì)Au8團(tuán)簇加入鹽酸后的刻蝕反應(yīng)的原位過程的研究。在加入鹽酸后的不同時(shí)間點(diǎn)取出溶液測試其QXAFS譜以了解Au8團(tuán)簇加入鹽酸后的刻蝕機(jī)理。實(shí)驗(yàn)結(jié)果表明Au8等團(tuán)簇金核原子數(shù)目比較少，Au-Au峰不明顯。而非金屬配位峰只有在反應(yīng)的初期有比較大的變化，，說明該反應(yīng)速度過快，需要嘗試降低反應(yīng)速度來獲得更為豐富的中間過程信息。該應(yīng)用研究驗(yàn)證了基于EPICS的QXAFS數(shù)據(jù)采集系統(tǒng)已能滿足開展動(dòng)態(tài)原位過程研究的要求。
[Abstract]:With the emergence and development of synchrotron radiation, synchrotron radiation experiments of various new emerging. The development of synchrotron radiation new experimental methods and use them to carry out research on scientific problems in related fields has become an important content of.X ray synchrotron radiation field absorption fine structure (X-ray Absorption Fine Structure, XAFS) is an analysis method with the development of synchrotron radiation source and gradually mature strong structure.
Different from ordinary XAFS experimental methods used by the "step-by-step" mode of data acquisition, fast scanning X ray absorption fine structure (Quick-scanning X-rayAbsorption Fine Structure, QXAFS) by using the experimental method of "data collection on-the-fly", can be in double crystal monochromator (Double Crystal Monochromator, DCM) can complete the data acquisition work of a XAFS in order to obtain experimental spectra of the second sample process for the movement of QXAFS in the experimental.QXAFS spectra method, suitable for carrying out the catalytic industry, chemical process, research on dynamic process in situ biological sensing and material science. XAFS (Energy-Dispersive X-rayAbsorption Fine and energy dispersive Structure, EDXAFS), XAFS (pump-probe X-ray pump probe Absorption Fine Structure XAFS) and other experimental methods for time-resolved compared, this method does not need to change the beam line station The existing structure can be compatible with the beamline station that implements the common XAFS experiment method, and is especially suitable for the time resolved XAFS experiment method of XAFS beam line in Shanghai light source.
On the basis of extensive research on the related data acquisition system of beamline QXAFS at home and abroad, the related research on motion control and QXAFS data acquisition system based on EPICS operation platform is carried out.
1. for the shortcomings of Shanghai light source XAFS beamline QXAFS existing data acquisition system, complete the motion control and data acquisition system for QXAFS overall design scheme based on unified operation platform. In the system scheme, Scaler for Bragg motor for high stable operation of the control pulses were counted to obtain monochromatic light energy. High speed ADC for the current signal acquisition chamber samples before and after the independent operation of the hardware trigger signal source is respectively provided 1MHz hardware trigger signal to realize control and data acquisition system hardware synchronization. Three parts hardware configuration were completed in the laboratory of software development and off-line debugging and the whole hardware system the integration and debugging.
2. in Shanghai light source XAFS beam line station to carry out the research and test of QXAFS data acquisition system based on EPICS. The study tested QXAFS experimental methods improve signal-to-noise ratio of the experimental conditions, including the selection of the sampling rate of ADC, Bragg motor subdivision, T2 motor compensation in energy scanning process; test configuration parameters the current amplifier of QXAFS spectrum and the influence of different smooth integration time on QXAFS spectrum in the high K region. Through 7.5um and standard standard samples of ordinary XAFS spectrum copper foil for comparison, that based on the number of QXAFS EPICS data acquisition system not only acquisition speed, good signal-to-noise ratio collected by QXAFS spectrum, and the system has high stability and repeatability.
The application of the system to carry out the research on the process of standing in situ etching reaction of Au8 clusters after the addition of hydrochloric acid in Shanghai light source beamline XAFS. Remove the solution to test its QXAFS spectrum to understand the mechanism of etching Au8 clusters after adding hydrochloric acid. At different time points after addition of hydrochloric acid the experimental results show that the Au8 clusters of gold atom the number is relatively small, the Au-Au peak is not obvious. Instead of metal coordination peaks only have relatively large changes in the initial reaction, the reaction speed is too fast, need to try to reduce the reaction speed to obtain more information rich. The intermediate process of application of validation of the QXAFS EPICS data acquisition system can meet research in situ dynamic process based on the requirements.

【學(xué)位授予單位】：中國科學(xué)院研究生院（上海應(yīng)用物理研究所）
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2015
【分類號(hào)】：TL544;TP274.2

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