TJAS和SJH感谢英国工程和物理科学研究理事会（批准号EP / G035954 / 1和EP / L01548X / 1）资金支持。笔者要感谢为与核先进制造研究中心的研究能力相关的泰坦G2 80-200 S / TEM提供的资金从女王陛下政府（UK）的支持。

1.纳米颗粒合成<ol><li>在在RT75毫升乙二醇溶解10克聚乙烯吡咯烷酮（PVP）（MW = 10,000克/摩尔）。 400毫克的AgNO 3添加到该溶液中。 </li><li>搅拌溶液直至硝酸银于1℃min的恒定速率完全溶解，并随后热在热板上，以100℃-1。让反应继续进行，在100℃1.5小时。 </li><li>加入175毫升蒸馏水并冷却至室温。离心机在8000 XG，除去上清液，再分散的纳米粒子在50毫升的蒸馏水。重复三次。 </li><li>在RT溶于500毫升乙二醇将500mg的PVP（55,000克/摩尔）。该溶液中，从以前的步骤27.8毫升Ag纳米颗粒悬浮液添加到1000毫升圆底烧瓶中。加热在100℃下将烧瓶10分钟。 </li><li>添加四氯三水至1000毫升的水，以形成AUCL 4的0.2mM的溶液- （ 水溶液） </sub&gt;。添加100，200，300或400毫升分装在0.2毫AUCL 4 - （ 水溶液）滴加至在先前步骤（原子％的Ag 93金7原子％），得到平均组成Ag93Au7的AgAu纳米颗粒获得的溶液中，Ag82Au18（银82分别％金18at％），Ag78Au22（银78％，在22金在％）和Ag66Au34（银66％，在18金在％）。 </li><li>冷却至室温，然后用蒸馏水冲洗通过连续多轮离心三次在8000 xg离心，除去50毫升蒸馏水上清，再分散的。添加0.05毫升纳米颗粒溶液至10ml去离子水。 </li></ol>透射电镜2.样品制备<ol><li>吸管大约0.05毫升到一个多孔的/连续碳TEM网格的纳米颗粒溶液。使用用于铍的TEM格栅上，以限制杂散X射线的金属支撑，但如果有的在样品的EDX谱与铜或金的兴趣不重叠峰的Cu或Au网格就足够了。使用大我sh的大小（ 例如，200目），以尽量减少从网格阴影的可能性。 </li><li>纳米颗粒溶液干燥后，洗涤在纯甲醇或乙醇的网格清洁TEM网格。同时它使用抗毛细管交叉镊子举行吸管滴10-20在TEM网格。从使用上至电网的边缘轻轻触摸滤纸在网格的每个下降后除去任何过量的液体。 </li><li>在约80℃（优选在真空中）退火网格通过除去或固定的任何剩余的污染，以减少电子束下的污染。 </li></ol> 3.探测器阴影的表征<ol><li>透射电镜上支持电网进入断层扫描架，然后装入纳米粒子支架插入到TEM。 </li><li>等待显微镜真空达到一个合适的稳定值（低于约1.8×10 -7托）。开柱阀，并确保电子束可在显微镜的荧光SC可见颖。 </li><li>对齐STEM。 注:在这里，一个泰坦G2探头端像差修正路线，在200千伏与描述2020年的断层扫描架一起操作STEM仪器。对于其他显微镜最佳比对程序可以从这些描述略有不同。 <ol><li>在STEM衍射模式下，使用失焦的阴影图像以使样品eucentric高度。要做到这一点，按在搜索选项卡中的阿尔法摇摆按钮倾斜±15°之间的阶段，通过调节Z轴高度最小化特征的样本中任何运动。 </li><li>移动样品，使得光束是在样品中的孔，并确保由定心在一个下开口的阴影了适当的聚光开口正确对齐聚焦在探测器的图像。摆动的强度，并确保聚焦的探针不移动检查光束倾斜失准。 </li><li>移动样品，使无定形碳的面积在图和聚焦是我在衍射模式，以获得Ronchigram。摆焦点Ronchigram中观察畸变，并更正如果需要的话，这些（ 例如，散光和轴向昏迷）。 </li></ol></li><li>通过选择"显示曲目"，在"搜索"选项卡，然后按照方格，同时成像的轮廓跟踪方格（一个接近电网的中心）的轮廓。这使得它可以直接以确保后续测量为处于网格正方形的中间，以减少从所述支撑栅格遮蔽的可能性的纳米颗粒进行的。如果收购是在靠近格酒吧一对探测器将在一个更大的范围标本的倾斜角度被隐藏的粒子进行。 </li><li>找到网格正方形的中间部分内的代表粒子。倾斜支架的最大倾斜范围（通常为±70°），同时成像，以确保该纳米颗粒不被GRI遮蔽在大架倾斜Ð吧。 </li><li>使用恒定的采集时间（ 例如 ，5分钟），在整个范围的倾斜角获得HAADF和EDX光谱图像用的5-10°之间的角增量（通常为±70°）。首先，通过点击获取在成像窗格中获得的概述HAADF形象。通过在这个图像，然后按采集拖动框中选择围绕纳米粒子的映射窗口。 </li><li>提取EDX谱图像特性X射线的计数在图像处理软件打开光谱datacubes（作为RAW文件），以确定数据采集的时间间隔。然后，总结，通过使用slice2D和总和功能对应于感兴趣的峰的能量的信道的datacube的切片的强度，脚本作为补充代码1-3。 </li></ol> 4. EDX断层扫描采集<ol><li>重复步骤3.1-3.5感兴趣的纳米颗粒样品。 </li><li>收购HAADF一个第二与上一节的倾斜角度的范围内试样的检测器遮蔽特性决定的时间间隔EDX谱图像（通常为±70°），以相同的方式与步骤3.6。 </li></ol> 5.重建和可视化<ol><li>通过以下方法之一编译倾斜系列HAADF图像转化成MRC文件格式: <ol><li>进口HAADF tifs作为"图像序列"，然后再使用MRC作家在图像可视化软件12（文件&gt;另存为&gt; MRC作家）。 </li><li>或者，使用tif_to_mrc函数在断层软件包13。 </li></ol></li><li>在所选择的软件交叉关联HAADF图像来获得倾斜系列的粗略对准。保存校准数据无论是作为.sft文件或文件xcorr.txt。在断层扫描软件设置在设置过滤器窗口，提供了在互相关窗格中的尖锐的峰的过滤器。 &lt;OL&gt; <li>随后，记者继续在计算路线班次窗口，为整个系列的倾斜进行互相关。重复排列，直到当地的转变低于1个像素，以确保保存所有文件转移在每一步为文本。 注意:在执行互相关时使用的过滤器的仔细设定有时需要确保倾斜系列数据的良好对准。 </li></ol></li><li>在图像处理软件，加载所获取的光谱datacubes并提取是能量通道的使用slice3d和总和的脚本函数对应于感兴趣的元素求和切片图，脚本作为补充代码4和5。 </li><li>应用从HAADF图像提取的EDX元素映射确定的路线。选择"对齐从数据视图使用位移"的应用对齐选项卡中断层重建软件执行此。 </li><li>如果需要的话，在执行倾斜轴调整在HAADF图片系列层析重建软件，并通过检查"，从倾斜轴调整任务使用更正"适用于HAADF图像和EDX地图"应用对齐"选项卡。 </li><li>重建为每个使用断层摄影软件包内实现的同步迭代重建技术（SIRT）算法所提取的EDX元素信号的断层数据组，确保重建的尺寸是为所有的元素是相同的。在断层重建软件，成立于并按继续（音量，20次迭代等大小）的重构卷窗口中的参数。确保重建参数是对每个元素是相同的。 </li><li>通过在图像可视化软件12选择图像&gt;栈&gt;正交视图提取分离的元素重建的orthoslices。 </li><li>构建和可视化进一步orthoslices，体积和表面重使用可视化软件重建nderings。加载所有元素重建，并确保规模设置正确，因为这往往不是发自.REC文件传输。 <ol><li>选择对象池并单击鼠标右键重建对象，然后选择orthoslice模块中提取orthoslice。在重建和选择体绘制右键单击提取体绘制。通过提取的重建和选择等值面右击等值面。 注意:通过阈值自动分割是一个更强大的方法，但其中的信噪比很差手工分割，可能需要从该纳米粒子体积为等值面可视外除去嘈杂体素。 </li></ol></li></ol>

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作者什么都没有透露。

这里介绍的协议提供了一种方法来确定在三维空间中的任何多元素的纳米颗粒的元素分布。在这里提出的AgAu纳米颗粒的情况下，两个元件的表面偏析明确确定并示于三组分偶合反应进行相关的催化产率。这清楚地表明在帮助解释纳米颗粒系统的物理和化学特性这技术的实用性。 由于是始终以TEM的情况下，应注意在样品制备注意保证最佳结果。彻底清洗和沉积所述纳米颗粒溶液后栅极的退火是特别重要的，以避免通过所需EDX断层扫描的大的电子剂量的碳污染的积聚。所使用的大剂量还可能导致严重的损坏多孔碳片，尤其是当对薄切片经常发现孔之间S，但氮化硅支持膜可以有利于纳米颗粒16的氧化。 的检测器遮蔽效应校正是很重要的，以产生一个准确的重建，尤其是当该方法是被应用在未来元素分布的定量映射。这可以通过检测器遮蔽的精确表征来实现，并随后改变电子剂量的纳米颗粒。另外，阴影可以通过收购后的修正系数光谱图像乘以补偿。然而，应用这种技术来在三维空间中提供定量信息尚不可行，由于限制在每个光谱图像可获得的X射线的计数纳米颗粒的电子束的损坏。 校准是必需的，以便为EDX检测器阴影补偿作为倾斜角为特定显微镜检测器保持器的组合的功能。该SHadowing应首先使用一个样本，让在不同的试样倾斜角度和个人的球形纳米粒子X射线计数没有变化预计将满足这一标准，当其成分是电子束在获取倾斜的时间下是稳定的决定系列。另外，对于晶体纳米颗粒，任何倾斜角度在该电子束被定向沿所述纳米颗粒的主要区域的轴应被删除，并在纳米颗粒应足够小，以避免显著X射线吸收。因此，当单个纳米颗粒的EDX谱获取图像的整个范围内的使用恒定采集时间可能试样倾斜角，在所测量的特性X射线强度的任何变化将是由于检测器单独遮蔽。采集时间，因此，剂量，然后在后续购置变化以补偿阴影意味着总信号计数是大约CON恒定在倾斜系列获得的所有光谱图像。 在比较HAADF或EELS成像模式，EDX断层数据采集仍处于早期阶段。尽管引入X射线检测器的高立体角EDX断层摄影的主要限制，这是常有用于二维EDX成像的情况下，是低的信号。尽管如此，人们优势EDX光谱可以缓缴EELS对于一些纳米粒子系统是在少量在相当大的纳米粒子的重元素的测定。较大的多组分纳米颗粒（&gt; 100nm）的往往非常适合于EDX研究，因为它们提供多个计数并有较少的问题与去卷积谱重叠，但应注意以使用经受小吸收高能量的X射线的峰。 总体而言，EDX断层扫描是确定纳米粒子在元素分布在三个层面的好方法，本书虽然是啊限于能够承受而不显著损害相对高的电子剂量纳米颗粒。在X射线检测器的STEM和断层试样夹具的进一步优化中的立体角进一步增大将允许该技术，以进一步推进，并成为在各个纳米颗粒的表征的重要方法。

该方法的目的是提供单一的纳米颗粒内的元件的三维分布的精确确定。这是通过结合使用能量色散型X射线（EDX）光谱与在扫描透射电子显微镜（STEM）进行层析重建进行。 能量色散X射线光谱仪一直被用来作为一种技术来量化和空间映射本透射电镜的样品中的元素。具有高角环形暗场（HAADF）STEM断层扫描的出现为结晶材料1的三维成像，能量色散X射线断层摄影术中还提出，以允许在三个维度2元素分布的测定方法。然而，早期的研究是有限的，由于X射线检测器的透射型电子显微镜中的设计。特别是这些传统的德tector设计有相对较低的收集效率和大范围的倾角测量没有信号，由于角度从样品架2,3阴影。的（扫描）透射型电子显微镜中引进X射线检测器的新几何设计取得了能量分散型X射线断层摄影术的可行技术，并已导致了许多最近的研究4-6。 HAADF STEM成像是一种广泛使用的电子断层扫描成像模式，并且能够提供在基于所述HAADF信号强度的原子序数灵敏度特定的情况下组成的信息。例如，HAADF断层扫描是非常适合于具有离散元素的区域， 例如 ，纳米颗粒的研究中，明确定义的核-壳形态7中 ，但是，当元件具有一个更复杂的分布，不能使用。电子能量损失谱（EELS）提供了补充的方法，用于确定三维eleme干8中ntal分布。在这种技术中，入射电子束的能量损失被用来确定样品的组成和这种具有较高信噪比比通常是由EDX光谱9得到的优点。 EELS的缺点是，多次散射考虑强加于试样厚度严格的限制，并在几种情况下分析由延迟性边缘或重叠光谱特征的存在复杂。因此，EDX光谱通常更适合于研究重元素，例如那些常与催化或电浆纳米粒子系统9相关联。此外，作为一个完整的光谱图像被收集在EDX光谱学是简单的追溯识别意想不到的元素，这是在能量过滤透射电子显微镜（EFTEM）和EELS更困难的，因为进行元素信息重叠或作为外的频率的光谱范围内的数据集的。 对于EDX断层扫描的理想的样品的几何形状由悬浮在真空和沿断层倾斜轴线4定向的针形的样品。这种情况下，确保了在任何倾斜角度由任样品或样品支架的EDX检测器没有遮蔽。然而，对于纳米颗粒系统所需的针形样品的组装是具有挑战性的10和样品制备通常由简单地转印纳米颗粒上碳薄膜的TEM支撑网格。这些栅极与一个断层试样夹持器专门设计的，以便它可以倾斜，以大角度使用（≈±75°），但遮蔽该范围试样倾斜角的范围内的EDX检测器是不可避免的，并可能会降低所得断层的质量重建。此遮蔽是一个特定的显微镜检测器保持器设置的特性，因此可以阻止收购之前11通过适当的校准样品测量开采。单球形纳米粒子是一种理想的校准样品从这些样品的X射线计数的强度应在所有的倾斜角度保持不变。该探测器阴影然后，可以由不同的每个角度，或数据采集后，用修正系数相乘采集时间进行补偿。在使用前一种方法，因为这减少了电子剂量同时最大化信噪比。

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Titan G2 80-200 STEM</td>
			<td>FEI</td>
			<td></td>
			<td>With Super-X detector</td>
		</tr>
		<tr>
			<td>2020 tomography holder</td>
			<td>Fischione</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Carbon film on 200 mesh copper grid</td>
			<td>Agar Scientific</td>
			<td>AGS160</td>
			<td></td>
		</tr>
		<tr>
			<td>EDX Acquisition software</td>
			<td>Bruker</td>
			<td></td>
			<td>Esprit</td>
		</tr>
		<tr>
			<td>Tomographic alignment and reconstruction software</td>
			<td>FEI</td>
			<td></td>
			<td>Inspect3D, alternatives available</td>
		</tr>
		<tr>
			<td>Tomographic alignment and reconstruction software package</td>
			<td>University of Colorado</td>
			<td></td>
			<td>IMOD, alternatives available</td>
		</tr>
		<tr>
			<td>Visualisation software</td>
			<td>FEI</td>
			<td></td>
			<td>Avizo, alternatives available</td>
		</tr>
		<tr>
			<td>Image processing software</td>
			<td>Gatan</td>
			<td></td>
			<td>Digital Micrograph, alternatives available</td>
		</tr>
		<tr>
			<td>Image visualisation software</td>
			<td>Open Source</td>
			<td></td>
			<td>Fiji, alternatives available</td>
		</tr>
		<tr>
			<td>Polyvinyl-pyrrolidone</td>
			<td>Sigma-Aldrich</td>
			<td>856568</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethylene glycol</td>
			<td>Sigma-Aldrich</td>
			<td>V900208</td>
			<td></td>
		</tr>
		<tr>
			<td>Silver nitrate</td>
			<td>Sigma-Aldrich</td>
			<td>209139</td>
			<td></td>
		</tr>
		<tr>
			<td>Benchtop Centrifuge</td>
			<td>Thermo Scientific</td>
			<td>75007200</td>
			<td></td>
		</tr>
		<tr>
			<td>Round bottom flask</td>
			<td>Sigma-Aldrich</td>
			<td>Z41,452-2</td>
			<td>1000mL</td>
		</tr>
		<tr>
			<td>Hydrogen tetrachloroaurate trihydrate</td>
			<td>Sigma-Aldrich</td>
			<td>520918</td>
			<td></td>
		</tr>
	</tbody>
</table>

energy dispersive x-ray tomography for 3d elemental mapping of individual nanoparticles

Energy dispersive X-ray spectroscopy within the scanning transmission electron microscope (STEM) provides accurate elemental analysis with high spatial resolution, and is even capable of providing atomically resolved elemental maps. In this technique, a highly focused electron beam is incident upon a thin sample and the energy of emitted X-rays is measured in order to determine the atomic species of material within the beam path. This elementally sensitive spectroscopy technique can be extended to three dimensional tomographic imaging by acquiring multiple spectrum images with the sample tilted along an axis perpendicular to the electron beam direction.
Elemental distributions within single nanoparticles are often important for determining their optical, catalytic and magnetic properties. Techniques such as X-ray tomography and slice and view energy dispersive X-ray mapping in the scanning electron microscope provide elementally sensitive three dimensional imaging but are typically limited to spatial resolutions of &gt; 20 nm. Atom probe tomography provides near atomic resolution but preparing nanoparticle samples for atom probe analysis is often challenging. Thus, elementally sensitive techniques applied within the scanning transmission electron microscope are uniquely placed to study elemental distributions within nanoparticles of dimensions 10-100 nm.
Here, energy dispersive X-ray (EDX) spectroscopy within the STEM is applied to investigate the distribution of elements in single AgAu nanoparticles. The surface segregation of both Ag and Au, at different nanoparticle compositions, has been observed.

探测器的阴影在泰坦G2 ChemiSTEM 2020年断层扫描架的特征显示在图1A。这里使用的检测器是超级-X探测器，在其中四个探测器在围绕光轴90°等方位角使用，导致大于0.6 SR 14的检测器的立体角。探测器的表征允许在图1B显示的补偿断层采集时间确定。这些采集时间的应用后在各倾斜角度的计数应该保持为单一的纳米粒子大致恒定， 如图1C所示 。 在STEM使用EDX断层扫描双金属纳米AgAu由电置换反应合成，进行了调查。在该反应中，AUCL 4中的溶液-是加入Ag纳米颗粒种子。金降低该纳米颗粒的Ag的表面上被氧化，从而导致在初始种子的双金属组合物和空洞化。以前，人们认为Ag和Au形成的均质合金这整个过程中，而且在催化和光学特性的变化是只是由于空鼓和散装成分变化。然而，三维元素映射使用由电反应（ 图2）中合成的AgAu纳米颗粒内的EDX断层扫描显示表面偏析进行。在低金组成，纳米粒子显示效果清晰金表面偏析。然而，由于在Au含量增加该表面偏析切换，使得对于最高的Au含量有明显的Ag表面偏析（ 图3）。表面偏析的这种开关由不同合成了一个三组分偶联反应在炔丙胺的收益率变化相关这些AgAu纳米粒子的成分耳鼻喉科。 通过重建切片是垂直于电子束的方向上提供了一个比较标准的二维元素地图。初始地图包含在沿光束的方向相加的合成信息，这往往可能会非常棘手解释由于重叠不同组成的区域，或在AgAu的情况下的纳米颗粒这里的调查，由于包含在顶部和底部的在突起（ 图3A-C）的表面。通过重建以切片允许移除与颗粒的顶部和底部表面关联的强度，并因此导致在表面偏析的在这种情况下（ 图3D-F）的一个更清楚的显示。 <img alt="图1" src="/files/ftp_upload/52815/52815fig1.jpg" /> <strong&gt;图1. 表征使用单个AgAu纳米粒子探测器遮蔽的（A）Ag和Au的X射线峰的作为倾斜角度的从单个AgAu纳米颗粒的函数采用一组采集时间（5分钟）时的计数。由（A）测定（B）中的采集时间，并随后用于采集倾斜系列。 （C）使用来自（B）中的采集时间时的Ag和Au的X射线峰的计数作为倾斜角度的从单个AgAu纳米颗粒的功能。计数仍然在所有的倾斜角大致不变。从Slater等 15。 <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/52815/52815fig1large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> <img alt="图2" src="/files/ftp_upload/52815/52815fig2.jpg" /> 图2。 </strong&gt;的低含量的Au纳米AgAu（A）Orthoslice通过金重建的重建 。 （B）Orthoslice通过银重建。通过orthoslices（A）和（B）显示在该纳米颗粒清晰的金表面偏析采取（C）线轮廓。银和Au重建的（D）表面可视化。从Slater等 15。 <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/52815/52815fig2large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> <img alt="图3" src="/files/ftp_upload/52815/52815fig3.jpg" /> 图3. 重建金含量高AgAu纳米颗粒。（A）金的2D地图EDX和（B）的Ag 2D地图EDX。 （C）行PROFIL通过2D EDX图（A）和（B）中示出在确定从2D此纳米粒子表面偏析的难度采取ë单独映射。 （D）Orthoslice通过金重建。 （E）Orthoslice通过银重建。 （F）通过orthoslices（D）和（E）显示在该纳米颗粒清晰的银表面偏析采取线轮廓。银和Au重建的（G）表面可视化。从Slater等 15。 <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/52815/52815fig3large.jpg" target="_blank">请点击此处查看该图的放大版本。</a>

Watch this Scientific Journal Video about Energy Dispersive X-ray Tomography for 3D Elemental Mapping of Individual Nanoparticles at JoVE.com

Energy Dispersive X-ray Tomography for 3D Elemental Mapping of Individual Nanoparticles

The use of energy dispersive X-ray tomography in the scanning transmission electron microscope to characterize elemental distributions within single nanoparticles in three dimensions is described.

能量色散X射线断层摄影术对个人纳米3D元素映射

Energy dispersive X-ray spectroscopy within the scanning transmission electron microscope (STEM) provides accurate elemental analysis with high spatial ...

energy-dispersive-x-ray-tomography-for-3d-elemental-mapping

Nanyang Technological University

Research

JoVE Journal

Engineering

11.7K 次观看.  University of Manchester. The use of energy dispersive X-ray tomography in the scanning transmission electron microscope to characterize elemental distributions within single nanoparticles in three dimensions is described.

视频: Energy Dispersive X-ray Tomography for 3D Elemental Mapping of Individual Nanoparticles

Reservoir Condition Pore-scale Imaging of Multiple Fluid Phases Using X-ray Microtomography

X-ray microtomography was used to image, at a resolution of 6.6 &#181;m, the pore-scale arrangement of residual carbon dioxide ganglia in the pore-space of a carbonate rock at pressures and temperatures representative of typical formations used for CO2 storage. Chemical equilibrium between the CO2, brine and rock phases was maintained using a high pressure high temperature reactor, replicating conditions far away from the injection site. Fluid flow was controlled using high pressure high temperature syringe pumps. To maintain representative in-situ conditions within the micro-CT scanner a carbon fiber high pressure micro-CT coreholder was used. Diffusive CO2 exchange across the confining sleeve from the pore-space of the rock to the confining fluid was prevented by surrounding the core with a triple wrap of aluminum foil. Reconstructed brine contrast was modeled using a polychromatic x-ray source, and brine composition was chosen to maximize the three phase contrast between the two fluids and the rock. Flexible flow lines were used to reduce forces on the sample during image acquisition, potentially causing unwanted sample motion, a major shortcoming in previous techniques. An internal thermocouple, placed directly adjacent to the rock core, coupled with an external flexible heating wrap and a PID controller was used to maintain a constant temperature within the flow cell. Substantial amounts of CO2 were trapped, with a residual saturation of 0.203 &#177; 0.013, and the sizes of larger volume ganglia obey power law distributions, consistent with percolation theory.

We present a methodology for the imaging of multiple fluid phases at reservoir conditions by the use of x-ray microtomography. We show some representative results of capillary trapping in a carbonate rock sample.

多重流体相储层孔隙条件级成像使用X射线微断层

X-ray microtomography was used to image, at a resolution of 6.6 &#181;m, the pore-scale arrangement of residual carbon dioxide ganglia in the pore-space ...

科研

工程学

Failure Analysis of Batteries Using Synchrotron-based Hard X-ray Microtomography

Imaging morphological changes that occur during the lifetime of rechargeable batteries is necessary to understand how these devices fail. Since the advent of lithium-ion batteries, researchers have known that the lithium metal anode has the highest theoretical energy density of any anode material. However, rechargeable batteries containing a lithium metal anode are not widely used in consumer products because the growth of lithium dendrites from the anode upon charging of the battery causes premature cell failure by short circuit. Lithium dendrites can also form in commercial lithium-ion batteries with graphite anodes if they are improperly charged. We demonstrate that lithium dendrite growth can be studied using synchrotron-based hard X-ray microtomography. This non-destructive imaging technique allows researchers to study the growth of lithium dendrites, in addition to other morphological changes inside batteries, and subsequently develop methods to extend battery life.

Synchrotron-based hard X-ray microtomography is used to image the electrochemical growth of dendrites from a lithium metal electrode through a solid polymer electrolyte membrane.

电池的使用同步为基础的硬X射线微断层故障分析

Imaging morphological changes that occur during the lifetime of rechargeable batteries is necessary to understand how these devices fail. Since the advent ...

Measurement of X-ray Beam Coherence along Multiple Directions Using 2-D Checkerboard Phase Grating

A procedure for a technique to measure the transverse coherence of synchrotron radiation X-ray sources using a single phase grating interferometer is reported. The measurements were demonstrated at the 1-BM bending magnet beamline of the Advanced Photon Source (APS) at Argonne National Laboratory (ANL). By using a 2-D checkerboard &#960;/2 phase-shift grating, transverse coherence lengths were obtained along the vertical and horizontal directions as well as along the 45&#176; and 135&#176; directions to the horizontal direction. Following the technical details specified in this paper, interferograms were measured at different positions downstream of the phase grating along the beam propagation direction. Visibility values of each interferogram were extracted from analyzing harmonic peaks in its Fourier Transformed image. Consequently, the coherence length along each direction can be extracted from the evolution of visibility as a function of the grating-to-detector distance. The simultaneous measurement of coherence lengths in four directions helped identify the elliptical shape of the coherence area of the Gaussian-shaped X-ray source. The reported technique for multiple-direction coherence characterization is important for selecting the appropriate sample size and orientation as well as for correcting the partial coherence effects in coherence scattering experiments. This technique can also be applied for assessing coherence preserving capabilities of X-ray optics.

The measurement protocol and data analysis procedure are given for obtaining transverse coherence of a synchrotron radiation X-ray source along four directions simultaneously using a single 2-D checkerboard phase grating. This simple technique can be applied for complete transverse coherence characterization of X-ray sources and X-ray optics.

使用2-D棋盘相位光栅X射线束相干测量沿多个方向

A procedure for a technique to measure the transverse coherence of synchrotron radiation X-ray sources using a single phase grating interferometer is ...

Protocol of Electrochemical Test and Characterization of Aprotic Li-O2 Battery

We demonstrate a method for electrochemical testing of an aprotic Li-O2 battery. An aprotic Li-O2 battery is made of a Li-metal anode, an aprotic electrolyte, and an O2-breathing cathode. The aprotic electrolyte is a solution of lithium salt with aprotic solvent; and porous carbon is commonly used as the cathode substrate. To improve the performance, an electrocatalyst is deposited onto the porous carbon substrate by certain deposition methods, such as atomic layer deposition (ALD) and wet-chemistry reaction. The as-prepared cathode materials are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray absorption near edge structure (XANES). A Swagelok-type cell, sealed in a glass chamber filled with pure O2, is used for the electrochemical test on a battery test system. The cells are tested under either capacity-controlled mode or voltage controlled mode. The reaction products are investigated by electron microscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, and Raman spectroscopy to study the possible pathway of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). This protocol demonstrates a systematic and efficient arrangement of routine tests of the aprotic Li-O2 battery, including the electrochemical test and characterization of battery materials.

Protocol of Electrochemical Test and Characterization of Aprotic Li-O2 Battery

A protocol for the electrochemical testing of an aprotic Li-O2 battery with the preparation of electrodes and electrolytes and an introduction of the frequently used methods of characterization is presented here.

电化学测试的协议及表征非质子锂的O<sub&gt; 2</sub&gt;电池

We demonstrate a method for electrochemical testing of an aprotic Li-O2 battery. An aprotic Li-O2 battery is made of a Li-metal anode, an aprotic ...

Dynamic Pore-scale Reservoir-condition Imaging of Reaction in Carbonates Using Synchrotron Fast Tomography

Underground storage permanence is a major concern for carbon capture and storage. Pumping CO2 into carbonate reservoirs has the potential to dissolve geologic seals and allow CO2 to escape. However, the dissolution processes at reservoir conditions are poorly understood. Thus, time-resolved experiments are needed to observe and predict the nature and rate of dissolution at the pore scale. Synchrotron fast tomography is a method of taking high-resolution time-resolved images of complex pore structures much more quickly than traditional &#181;-CT. The Diamond Lightsource Pink Beam was used to dynamically image dissolution of limestone in the presence of CO2-saturated brine at reservoir conditions. 100 scans were taken at a 6.1 &#181;m resolution over a period of 2 hours. The images were segmented and the porosity and permeability were measured using image analysis and network extraction. Porosity increased uniformly along the length of the sample; however, the rate of increase of both porosity and permeability slowed at later times.

Synchrotron fast tomography was used to dynamically image dissolution of limestone in the presence of CO2-saturated brine at reservoir conditions. 100 scans were taken at a 6.1 &#181;m resolution over a period of 2 h.

用同步快速反应层析成像动态孔隙规模油藏条件下成像碳酸盐

Underground storage permanence is a major concern for carbon capture and storage. Pumping CO2 into carbonate reservoirs has the potential to dissolve ...

In Depth Analyses of LEDs by a Combination of X-ray Computed Tomography (CT) and Light Microscopy (LM) Correlated with Scanning Electron Microscopy (SEM)

In failure analysis, device characterization and reverse engineering of light emitting diodes (LEDs), and similar electronic components of micro-characterization, plays an important role. Commonly, different techniques like X-ray computed tomography (CT), light microscopy (LM) and scanning electron microscopy (SEM) are used separately. Similarly, the results have to be treated for each technique independently. Here a comprehensive study is shown which demonstrates the potentials leveraged by linking CT, LM and SEM. In depth characterization is performed on a white emitting LED, which can be operated throughout all characterization steps. Major advantages are: planned preparation of defined cross sections, correlation of optical properties to structural and compositional information, as well as reliable identification of different functional regions. This results from the breadth of information available from identical regions of interest (ROIs): polarization contrast, bright and dark-field LM images, as well as optical images of the LED cross section in operation. This is supplemented by SEM imaging techniques and micro-analysis using energy dispersive X-ray spectroscopy.

In Depth Analyses of LEDs by a Combination of X-ray Computed Tomography CT and Light Microscopy LM Correlated with Scanning Electron Microscopy SEM

A workflow for comprehensive micro-characterization of active optical devices is outlined. It contains structural as well as functional investigations by means of CT, LM and SEM. The method is demonstrated for a white LED which can be still be operated during characterization.

在通过X射线计算机断层扫描（CT）和与扫描电子显微镜相关光学显微镜（LM）的一个组合的LED深度分析（SEM）的

In failure analysis, device characterization and reverse engineering of light emitting diodes (LEDs), and similar electronic components of ...

Applying X-ray Imaging Crystal Spectroscopy for Use as a High Temperature Plasma Diagnostic

X-ray spectra provide a wealth of information on high temperature plasmas; for example electron temperature and density can be inferred from line intensity ratios. By using a Johann spectrometer viewing the plasma, it is possible to construct profiles of plasma parameters such as density, temperature, and velocity with good spatial and time resolution. However, benchmarking atomic code modeling of X-ray spectra obtained from well-diagnosed laboratory plasmas is important to justify use of such spectra to determine plasma parameters when other independent diagnostics are not available. This manuscript presents the operation of the High Resolution X-ray Crystal Imaging Spectrometer with Spatial Resolution (HIREXSR), a high wavelength resolution spatially imaging X-ray spectrometer used to view hydrogen- and helium-like ions of medium atomic number elements in a tokamak plasma. In addition, this manuscript covers a laser blow-off system that can introduce such ions to the plasma with precise timing to allow for perturbative studies of transport in the plasma.

X-ray spectra provide a wealth of information on high temperature plasmas. This manuscript presents the operation of a high wavelength resolution spatially imaging X-ray spectrometer used to view hydrogen- and helium-like ions of medium atomic number elements in a tokamak plasma.

运用X射线成像光谱水晶的使用为高温等离子体诊断

X-ray spectra provide a wealth of information on high temperature plasmas; for example electron temperature and density can be inferred from line ...

Synchrotron X-ray Microdiffraction and Fluorescence Imaging of Mineral and Rock Samples

In this report, we describe a detailed procedure for acquiring and processing&#160;x-ray microfluorescence (&#956;XRF), and Laue and powder microdiffraction two-dimensional (2D) maps at beamline 12.3.2 of the Advanced Light Source (ALS), Lawrence Berkeley National Laboratory. Measurements can be performed on any sample that is less than 10 cm x 10 cm x 5 cm, with a flat exposed surface. The experimental geometry is calibrated using standard materials (elemental standards for XRF, and crystalline samples such as Si, quartz, or Al2O3 for diffraction). Samples are aligned to the focal point of the x-ray microbeam, and raster scans are performed, where each pixel of a map corresponds to one measurement, e.g., one XRF spectrum or one diffraction pattern. The data are then processed using the in-house developed software XMAS, which outputs text files, where each row corresponds to a pixel position. Representative data from moissanite and an olive snail shell are presented to demonstrate data quality, collection, and analysis strategies.

We describe a beamline setup meant to carry out rapid two-dimensional x-ray fluorescence and x-ray microdiffraction mapping of single crystal or powder samples using either Laue (polychromatic radiation) or powder (monochromatic radiation) diffraction. The resulting maps give information about strain, orientation, phase distribution, and plastic deformation.

矿物和岩石样品的同步辐射 x 射线 Microdiffraction 和荧光成像

In this report, we describe a detailed procedure for acquiring and processing&#160;x-ray microfluorescence (&#956;XRF), and Laue and powder ...

Pore-scale Imaging and Characterization of Hydrocarbon Reservoir Rock Wettability at Subsurface Conditions Using X-ray Microtomography

In situ wettability measurements in hydrocarbon reservoir rocks have only been possible recently. The purpose of this work is to present a protocol to characterize the complex wetting conditions of hydrocarbon reservoir rock using pore-scale three-dimensional X-ray imaging at subsurface conditions. In this work, heterogeneous carbonate reservoir rocks, extracted from a very large producing oil field, have been used to demonstrate the protocol. The rocks are saturated with brine and oil and aged over three weeks at subsurface conditions to replicate the wettability conditions that typically exist in hydrocarbon reservoirs (known as mixed-wettability). After the brine injection, high-resolution three-dimensional images (2 &#181;m/voxel) are acquired and then processed and segmented. To calculate the distribution of the contact angle, which defines the wettability, the following steps are performed. First, fluid-fluid and fluid-rock surfaces are meshed. The surfaces are smoothed to remove voxel artefacts, and in situ contact angles are measured at the three-phase contact line throughout the whole image. The main advantage of this method is its ability to characterize in situ wettability accounting for pore-scale rock properties, such as rock surface roughness, rock chemical composition, and pore size. The in situ wettability is determined rapidly at hundreds of thousands of points. 
The method is limited by the segmentation accuracy and X-ray image resolution. This protocol could be used to characterize the wettability of other complex rocks saturated with different fluids and at different conditions for a variety of applications. For example, it could help in determining the optimal wettability that could yield an extra oil recovery (i.e., designing brine salinity accordingly to obtain higher oil recovery) and to find the most efficient wetting conditions to trap more CO2 in subsurface formations.

This protocol is presented to characterize the complex wetting conditions of an opaque porous medium (hydrocarbon reservoir rock) using three-dimensional images obtained by X-ray microtomography at subsurface conditions.

利用 X 射线层析在地下条件下油气储层岩石润湿性的孔隙度成像与表征

In situ wettability measurements in hydrocarbon reservoir rocks have only been possible recently. The purpose of this work is to present a protocol to ...

An Efficient Method for Selective Desalination of Radioactive Iodine Anions by Using Gold Nanoparticles-Embedded Membrane Filter

Here, we demonstrate a detail protocol for the preparation of nanomaterials-embedded composite membranes and its application to the efficient and ion-selective removal of radioactive iodines. By using citrate-stabilized gold nanoparticles (mean diameter: 13 nm) and cellulose acetate membranes, gold nanoparticle-embedded cellulose acetate membranes (Au-CAM) have easily been fabricated. The nano-adsorbents on Au-CAM were highly stable in the presence of high concentration of inorganic salts and organic molecules. The iodide ions in aqueous solutions could rapidly be captured by this engineered membrane. Through a filtration process using an Au-CAM containing filter unit, excellent removal efficiency (&gt;99%) as well as ion-selective desalination result was achieved in a short time. Moreover, Au-CAM provided good reusability without significant decrease of its performances. These results suggested that the present technology using the engineered hybrid membrane will be a promising process for the large-scale decontamination of radioactive iodine from liquid wastes.

An efficient method for the rapid and ion-selective desalination of radioactive iodine in several aqueous solutions is described by using gold nanoparticles-immobilized cellulose acetate membrane filters.