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1、X射线吸收精细结构谱XAFS（实验方法和应用）Web of Science Search: “EXAFS” or “XAFS”(but not “XAS” too many false hits) 1971-1975: 8 Publications Last year: 743 Publications Last 10 years: 7,199 Publications XAFS Beamline Design Parameter 位于第三代上海同步辐射装置的BL14W1 是一个高性能的X射线吸收谱光束线站。在一期的七条光束线站中BL14W1设计为通用吸收谱线站。BL14W1 的光源是一个38
2、极Wiggler插入件，最大磁场为1.2T，磁场周期为80mm. XAFS光束线的主要光学部件包括一个准直镜，一个配有Si (111) 和 Si (311)的液氮冷却双晶单色器，一个聚焦镜，一个高次谐波抑制镜。光束线有聚焦和非聚焦两种工作模式，其中，聚焦模式下能量范围为422.5keV，非聚焦模式下的能量范围为3.550keV。 同步装置束线能量范围keV分辨率E/E光通量10kevPhs/sAS（澳大利亚）XAFS4-40510-5210-410121013SPing-8（日本）BL01B13.8-113310-5310-41091011Diamond（英国）I-204-3410-4 10-
3、51012BSRF（北京）1W1B4-301310-421011SSRF（上海）BL14W1450510-5210-410121013国内外同类线站性能比较国内外同类线站性能比较Experimental StationPotential capabilityMinimum Detection Limit 1ppmIt is a general and high performance XAFS beamline, with high flux、high signal/noise ratio and fast data collection.XAFS analytical techniques
4、at SSRF32元高纯元高纯Ge探测器及探测器及XIA电子学系统电子学系统4元元Si漂移探测器及采集系统漂移探测器及采集系统Lytle 荧光电离室荧光电离室Oxford 电离室电离室五五维样品台品台掠入射平台掠入射平台 低温样品室低温样品室 (4K) 和高温炉和高温炉XAFS线站主要仪器设备线站主要仪器设备XAFS线站主要实验技术线站主要实验技术透射透射 XAFS （Transmission XAFS）荧光荧光 XAFS（Fluoresce XAFS）掠入射掠入射 XAFS （Grazing Incident XAFS） 原位原位 XAFS （In situ XAFS ）快速快速 XAFS
5、(QXAFS) Conventional XAFS and QXAFS spectra (5 Sec) of Cu foil at K edge measured at BL14W1 beamline in comparison with standard XAFS spectra (the data is from Chicago University XAFS library, which was measured in APS 13ID) comparison with APS standard XAFS spectraSR-XAFS实验框图XAFSXAFS在钙钛矿催化剂研究中的应用在钙
6、钛矿催化剂研究中的应用汽车尾气污染问题严重汽车尾气污染问题严重1.汽车尾气的污染物，CO、HC以及NOx等，严重威胁到人类的生活，对其治理受到全球范围的重视。2.世界上污染最为严重的二十个城市，出现频率最高的就是中国的城市，占据60%。3.大气污染问题与汽车尾气排放具有很高的相关性。4.引起的呼吸系统疾病(主要是慢性阻塞性肺病)在我国城市居民主要疾病死亡构成中占12.6%，59%以上的司机患有不同程度的呼吸道疾病5.国内不断提高汽车尾气排放处理标准。6.国内在尾气处理催化剂研究人员众多。Mazda: Worlds first application of single-nanocatalyst
7、 Mazda: Worlds first application of single-nanocatalyst technology in catalytic converterstechnology in catalytic convertersSelf-regeneration of a Pd-Self-regeneration of a Pd-perovskite catalyst for perovskite catalyst for automotive emissions automotive emissions controlcontrol用XAFS手段研究催化材料的重生问题，研
8、究其反应前后的结构变化，发现其在催化反应前后所处晶格和配位环境差异，解释了其能长期保持高活性的原因。 SPring-8Nature 418, 164 - 167 (11 July 2002) Improving catalytic converters为了提高催化剂的催化效率，科学家利用同步辐射装置开展很多原位实时监测反应过程的研究。XAFS可以提供很重要的在金属催化剂反应过程中，与局域结构和电子环境有关的原位动力学信息，他的动力学行为可以在ms, us,以至于ps. fs内研究。M. A. Newton et al., Nature Materials 2007, 6, 528-532; A
9、ngew. Chem Int. Ed. 2007, 45, 8629-8631Fig. 99: Normalised Pd K edge energy dispersive EXAFS spectra derived during a switch from a 5%NO/He feed to a 5%CO/He feed (both 75mlmin1 flow) at 673 K over a 1wt%Pd/10ZCA sample. Each spectrum was acquired in ca. 250 msecs. For clarity only 1 spectrum/second
10、 is plotted. The red to yellow shading is indicative of the switch from the NO to CO feed.Fig. 100: Infrared spectra (averaged over 9 reversible NO/CO switches) taken at the same time as the EXAFS spectra shown in Figure 99, collected with a 3 Hz spectral acquistion speed. The major gas phase and su
11、rface functionalities observed during the experiment are indicated. Again the shading of the flow of the graph indicates the change of reactive feedstock.国内的研究国内的研究汽车尾气净化装置及催化剂汽车尾气净化装置及催化剂通过EXAFS研究助剂Fe的添加对催化剂Pt/Ba/Al2O3 中Pt物种微观结构的影响，这种微观结构的改变对催化剂组分间的作用和催化性能产生了显著影响。Meng M et al.Applied Catalysis B: E
12、nvironmental 78 (2008) 38XAFSXAFS在电化学研究中应用在电化学研究中应用 “Ethanol is one of the most ideal reactants for fuel cells,” said Brookhaven chemist Radoslav Adzic. “Its easy to produce, renewable, nontoxic, relatively easy to transport, and it has a high energy density. A major hurdle to the commercial use of
13、direct ethanol fuel cells is the molecules slow, inefficient oxidation, which breaks the compound into hydrogen ions and electrons that are needed to generate electricity. Specifically, scientists have been unable to find a catalyst capable of breaking the bonds between ethanols carbon atoms. But at
14、 Brookhaven, scientists have found a winner. Made of platinum and rhodium atoms on carbon-supported tin dioxide nanoparticles, the research teams electrocatalyst is capable of breaking carbon bonds at room temperature and efficiently oxidizing ethanol into carbon dioxide as the main reaction product
15、. Other catalysts, by comparison, produce acetalhyde and acetic acid as the main products, which make them unsuitable for power generation. 氢电池：储存、运输困氢电池：储存、运输困难难甲醇电池：甲醇电池：CO中间物质中间物质乙醇电池：氧化困难，乙醇电池：氧化困难， “The ability to split the carbon-carbon bond and generate CO2 at room temperature is a completely
16、 new feature of catalysis,” Adzic said. “There are no other catalysts that can achieve this at practical potentials.”The main absorption peaks at the Rh and Pt edges have a very small potential dependence, indicating that the surfaces are only slightly oxidized, unlike the process that occurs with t
17、he pure Rh phase. It is likely that OH, which is present on the SnO2 surface in aqueous solutions, causes a shift in surface oxidation of Rh and Pt (Rh or PtOH formation)Measurements of metal metal (RhPt and PtRh) coordination numbers NRh-Pt and NPt-Rhenabled us to obtain the average composition of
18、the nanoparticles: x(Pt)/x(Rh) = NRh-Pt/NPt-Rh = 2.1(0.3), in reasonably good agreement with the ICP data x(Pt)/x(Rh)=1.5(0.2). The absolute values of these coordination numbers indicate the same size range (13 nm) as obtained by TEM. The obtained Pt and Rh coordination numbers have similar values 9
19、.5(0.8) and 10.8(0.8) respectively, consistent with homogeneous distribution of Pt and Rh throughout the particles.In addition, as the NPtPt/NPtRh and NRhPt/NRhRh ratios were found to be consistent, with the bulk ratios of Pt and Rh concentrations obtained independently byEXAFS and ICP, we conclude
20、that the Pt and Rh formed a quasi-random alloy. Further independent evidence towards that conclusion is the similarity between the PtPt, PtRh and RhRh bond lengths found by our EXAFS analysis: 2.743, 2.725 , and 2.705 , respectively, that is, characterized by a much smaller spread than between pure
21、Pt (2.775 ) and Rh (2.689 ).in situ IRRAS to identify the intermediates and products of ethanol oxidationXAS of Platinum Monolayer Fuel CellElectrocatalysts Unambiguous, Direct Correlationof Spectroscopy Data with Catalytic Properties(a) Models of pseudomorphic monolayers of Pt on three different su
22、bstrates inducing compressive strain (Ru(0001) and Pd(111) and expansive strain (Au(111). (b) Schematic of Pt monolayer electrocatalyst subjectto synchrotron X-rayK. Sasaki, R. R. Adzic. Synchrotron Radiatin News, 2009, 22, 17-21Structural and Electronic Properties of Platinum Nanoparticle Surface i
23、n an Aqueous System Probed by In Situ X-ray Absorption Spectroscopy其他几个与电池材料有关的例子LixNi0.5Mn0.5O2-cathodeMeasured at Ni K- and Mn K-edges alternately during discharge.0.1 Hz, averaged over 20 spectra. Lithiation speed C/4.5, starting with x=0.414.Oxidation state changes from Ni4+ over Ni3+ to Ni2+.Di
24、scharge of new lithium battery materials:Discharge of new lithium battery materials:LiLix xNiNi0.50.5MnMn0.50.5OO2 2Ni K-edgeLixNi0.5Mn0.5O2-cathodeMeasured at Ni K- and Mn K-edges alternately during discharge.0.1 Hz, averaged over 20 spectra. Lithiation speed C/4.5, starting with x=0.414.Significan
25、t changes in the EXAFS.Discharge of new lithium battery materials:Discharge of new lithium battery materials:LiLix xNiNi0.50.5MnMn0.50.5OO2 2Ni K-edgeLixNi0.5Mn0.5O2-cathodeMeasured at Ni K- and Mn K-edges alternately during discharge.0.1 Hz, averaged over 20 spectra. Lithiation speed C/4.5, startin
26、g with x=0.414.Oxidation state of Mn stays in a tetravalent state.Discharge of new lithium battery materials:Discharge of new lithium battery materials:LiLix xNiNi0.50.5MnMn0.50.5OO2 2Mn K-edge直接甲醇燃料电池直接甲醇燃料电池DMFCElectrochemical cell for in situ EXAFS of fuel cell electrodes on station 16.5 at the S
27、RS, DaresburyPEM fuel cell for in situ EXAFS studies of anode or cathode catalysts on station 16.5 at the SRS, Daresbury. The cell design enables the study of realistic catalyst loadings of 1 mg Pt per cm-2 of electrode area and operates under fully humidified conditions at 80 C.优点优点缺点缺点时间分辨时间分辨XAFS
28、XAFS在动力学研究中应用在动力学研究中应用QXAFS-催化催化-Pt/Al2O3-CO-氧化氧化时间时间分辨分辨分辨分辨XAFSXAFS在反在反在反在反应动应动力学力学力学力学应应用用用用时间时间分辨分辨分辨分辨XAFSXAFS在反在反在反在反应动应动力学力学力学力学应应用用用用Filming chemical reactionsThe study of transient states of matter that last nanoseconds (10-9 s), or even picoseconds (10-12 s), is one of the scientific chall
29、enges that the ESRF has taken up successfully. For example, researchers observed what happens to the C2H4I2 molecule in water when hit by a flash of laser light. The pump and probe technique used in this experiment may also help in the future to study nanomaterials and proteins in action.H. Ihee et
30、al., Science 2005, 309, 1223XAFSXAFS在多相催化中应用在多相催化中应用solid catalystgasesSurface eventsMolecular understandingAtomic scale constructionDynamic probe of operating state在在原子精度原子精度上设计、构筑高效催化剂；在上设计、构筑高效催化剂；在分子精度分子精度上揭示反应物向产物上揭示反应物向产物的转化；发展表征工具，的转化；发展表征工具，原位、实时、高空间分辨原位、实时、高空间分辨地表征地表征工作状态工作状态催化催化剂，实现对催化过程本质
31、的理解剂，实现对催化过程本质的理解 DOE Report 2007Advancing Time-resolved Methods in Monitoringand Characterization of CatalystsReduction of a CuO/ZnO/Al2O3 methanol catalyst in H2 atmosphere, observed with 50 ms time resolution. Measurements performed at HASYLAB in collaboration with the group of B.S. Clausen.A nov
32、el fast monochromator: Drive systemA novel fast monochromator: Drive systemGoal: Faster (ms), wide spectral range, continuous movementCurrently up to 40 Hz possible 80 spectra / s 12.5 ms / spectrumExperiments at APS undulator 1-ID MonochromatorCatalytic reactorCuO/ZnO-catalyst: ReductionCuOCuCu K-e
33、dgeD Dt=200 sJ.-D. Grunwaldt and A. Baiker, ETH ZrichCuO/ZnO-catalyst: ReductionCuOCuCu K-edgeD Dt=200 sTomographic absorption spectroscopy:Entering the 3rd dimensionm m-XAFS in 2D and 3DCharacterization of multi component samples on mm-scale Valence distribution of elements2D-mapping:0.25 mm2 with
34、5 mm resolution: 10.000 spectra not feasible with conventional methods, 30 s/scan 3.5 days oscillating QEXAFS at moderate 10 Hz 8 min3D-Tomography:Even more time consumingFirst experiments at ESRF (BM) and APS (tapered undulator)Focussing with X-ray lenses Focal size 6 mm x 2 mm. Even dilute biologi
35、cal samples in fluorescence mode possible!XANES m m-tomographyr rotationotationt translationranslationI I1 1I I2 2I I0 0reference samplereference sampleL L2 2horizontal focal size: 6-10 mrefrarefrac ctivetivele lensnsmonochromaticmonochromaticX-rays fromX-rays fromoscillatingoscillatingmonochromator
36、monochromatorCollaboration with RWTH Aachen (B. Lengeler)and TU Dresden (C. Schroer)X-ray Absorption Spectroscopic Microscopy:From the Micro- to the NanoscaleXANES tomography: (a) schematic sketch of the sample.(b) Tomographic reconstruction of the sample on a virtual section at X-rayenergy E = 8995
37、 eV. From the tomographic data set, the full XANES spectraat each location on the virtual section can be reconstructed. Two examplespectra for locations shown in (b) are depicted in (c). (d) Relative concentrationsof metallic, monovalent, and bivalent Cu inside the glass capillary.The concentration
38、of bivalent copper is below the detection limit of themethod. Attenuation generated by elements other than Cu is shown in thelower right image.Measured Data acquire 10 spectra in 1 second sampling rate: 100 kHz 102 projections 91 points per projectionAt each position in the scan:Acquisition of tomog
39、raphic data set:over 90.000 spectra with 104 points each 7 GByte of raw datarotationrotationtranslationtranslationNear edge spectrum:Sample:CuO/ZnO catalyst in glass capillaryCu/ZnO catalystSample in glass capillary, outer diameter 500 mm, inner diameter 400 mm.Beam size: 10 mm x 10 mmSample below /
40、 above Cu K-edgeReconstructed spectra with referencesC.G. Schroer et al., Appl. Phys. Lett. 82, 3360 (2003)Reconstruction at different positions after several oxidation/reduction cycles: What happens to the catalyst during catalysis?All spectra can be decomposed into content of the Cu-oxides and Cu
41、to answer this question!Cu/ZnO catalyst: Cu distributionCu Cu(I) , 1.26 : 1 Average over whole cross section:Cu : Cu(I) = 51 : 49 Very detailed in situ observation of behaviour of real catalysts!XAFSXAFS在表面有机金属化学中应用在表面有机金属化学中应用XAFS在有机金属化学中在有机金属化学中应用用-Zeolite-IrXAFS在双金属纳米粒子研究中应用在双金属纳米粒子研究中应用Magnetic
42、nanoparticlesIron-platinum nanoparticles are known for their interesting magnetic properties. At the ESRF, they were subjected to successive treatments. The structural changes and their influence on the element-specific magnetic moments were monitored by the analysis of the X-ray absorption near-edg
43、e structure and the X-ray magnetic circular dichroism.The synthesised Fe50Pt50 particles were self-assembled on a silicon substrate and exposed to a soft hydrogen plasma. They were then annealed at 600C in order toachieve the chemically-ordered L10 phaseC. Antoniak et al., Phys. Rev. Lett. 97, 11720
44、1 (2006).Near edge X-ray absorption fine structureC 1s(C=C)* C=C：283.4 eVC 1s(C-H)* ring：285.2 eVC 1s(C-N) *ring：286.8 eV*CCJ. AM. CHEM. SOC. 9 VOL. 131, NO. 18, 2009上海光源上海光源XAFS线部分研究结果线部分研究结果 FeFe基超导材料高压基超导材料高压X X射线吸收谱结构研究射线吸收谱结构研究中科院物理所中科院物理所 赵忠贤赵忠贤 丁洪丁洪 孙力玲孙力玲用于用于XAFS 实验的金刚石实验的金刚石CeFeAsO1-xFx铁基超导
45、材料结构高压与超导临界温度关系高压X射线吸收谱（XAFS) 2008年春日本和中国科学家发现一种新型超导体年春日本和中国科学家发现一种新型超导体铁基超铁基超导材料。铁基超导材料的发现为高温超导研究和量子凝聚物导材料。铁基超导材料的发现为高温超导研究和量子凝聚物理带来了巨大的刺激和振奋，理带来了巨大的刺激和振奋，XAFS将从原子和电子结构上将从原子和电子结构上理解高温超导的深层机制理解高温超导的深层机制 ，利用，利用SSRF高通量、高能量分辨高通量、高能量分辨的的XAFS光束线，获得了高质量高压光束线，获得了高质量高压XAFS谱。谱。 经过辐照后，随时间增加，伴随主峰强度降低，吸收边能量位移，和
46、边前峰的强度降低特征，判定三价铁逐渐还原为二价铁原位研究离子液体（原位研究离子液体（BmimFeCl4)的铁的还原过程的铁的还原过程 中国科学院上海应用物理研究所中国科学院上海应用物理研究所此辐照反应的机理为：Fe（）受X射线激发产生光电子或俄歇电子，随后被Bmim+阳离子俘获，成为溶剂化电子，此溶剂化电子继而还原了Fe（），生成Fe（）；其次，Fe（）被还原为Fe（）与Bmim+阳离子的分解是一个竞争过程，Fe（）的被还原过程优先于Bmim+阳离子的分解，在小范围内的Fe（）基本上反应完全之后，Bmim+阳离子才开始分解。SnO2包裹的包裹的单分散超分散超顺磁磁Fe的氧化物的氧化物纳米米颗粒
47、粒的高温的高温稳定性研究定性研究 “ On the basis of XAFS results, it can be concluded that after the heating treatment 500 C for 4 h, Fe3O4-to- -Fe2O3 transition indeed occurred in core-shell structured iron-oxideSnO2 NPs. This indicates that O ions penetrate through SnO2 shells to oxidize Fe3O4. It is also found th
48、at the XAFS curves of the as prepared A and B are extremely similar, indicating that coating process did not largely affect local environment of Fe ions in B. ”APPLIED PHYSICS LETTERS 95, 183112 （2009） 蒋建中研究组，浙江大学蒋建中研究组，浙江大学RuHAp（羟基磷灰石基新型高效多相催化材料，（羟基磷灰石基新型高效多相催化材料，Ru （1 wt%）通过XAFS测试发现催化剂中存在两种Ru-O键，拟
49、合得到结构参数 键长：1.88和2.01，配位数分别为2.2和4.2。中国科学院大连化学物理研究所中国科学院大连化学物理研究所 王军虎王军虎PtFe 催化剂原位催化剂原位X射线表征射线表征中国科学院大连化学物理研究所中国科学院大连化学物理研究所 包信和包信和 PtFeSiO2催化剂中铁催化剂中铁K K边吸收谱及边前峰放大图边吸收谱及边前峰放大图 利用上海光源XAFS高通量特点，使用高温、通气原位反应炉，在国内首次获得了该催化剂的整个化学氧化和还原过程的原位XAFS谱。富氢条件下低温选择氧化CO的PtFe纳米催化剂表现出了高效的催化活性，为了进一步明确它的活性组分，采用原位XAFS表征，对反应过
50、程中Fe吸收边的位移的分析表明了原位生成的FeO为催化反应的活性组分；而Pt在整个反应过程中吸收边没有发生变化，一直以单质形式存在。原位原位XAFSXAFS射线吸收精细结构（射线吸收精细结构（X X) )PtFe纳米粒子催化剂的活性结构纳米粒子催化剂的活性结构PtPtPtPt的的的的L L L L3 3 3 3边吸收谱边吸收谱边吸收谱边吸收谱 Pt Pt以金属态存在！以金属态存在！H2 473 K1%CO, 0.5%O2, H2 balanceRT20%O2, He balance RTPtFe纳米粒子催化剂的活性结构纳米粒子催化剂的活性结构 反应过程中产生了反应过程中产生了FeOFeO物种！物种！FeFeFeFe的的的的K K K K边吸收谱边吸收谱边吸收谱边吸收谱PtFe纳米粒子催化剂的活性结构纳米粒子催化剂的活性结构H2 473 K reduction Fe0+ 1%CO, 0.5%O2, H2 balanceFeO 20%O2, He balanceFe2O3
