We acknowledge the services of Stanley Flegler, Carol Flegler, and Abigail Tirrell at the MSU Center for Advanced Microscopy. We thank Ray Clark and Mark Wilson for technical assistance with the set-up of the electrochemical etching apparatus. Earlier contributions from Anne Benjamin, Georg Bollen, Rafael Ferrer, David Lincoln, Stefan Schwarz and Adrian Valverde, and technical assistance from John Yurkon are also acknowledged. This work was partially supported by the National Science Foundation contract no. PHY-1102511 and PHY-1307233, Michigan State University and the Facility for Rare Isotope Beams, and Central Michigan University.

1.电化学腐蚀<ol><li> 实验装置 <ol><li> 仪器 注意:电化学蚀刻设置需要一个标准0 - 30伏直流（DC）台式电源和相应的电缆，分液漏斗，一个宽基底玻璃烧杯中，标准杆和效用钳电绝缘夹具。小螺丝，绝缘支座，和鳄鱼夹也将被要求。其他项目，下面描述并且在图1中的蚀刻装置的图所示，必须制造。 <ol><li>从约100毫米长直径6毫米铝棒使钨杆保持器。钻一个0.5mm直径大约为8毫米深的孔中的中心，并进行了螺纹孔为一个4-40螺钉在侧保持杆就位。 </li><li>从约100mm×30毫米x 3毫米厚的铜板制作反电极具有约75毫米×20毫米×1.5毫米深的水库磨成它，并在中心1.5毫米直径的孔。附上大约15毫米长的绝缘支座到反电极的背面。 </li><li>通过钻6毫米直径为8毫米深的孔成大约75×20×20mm的铜块作出的FEP捕手。 </li></ol></li><li> 钨棒的制备 <ol><li>使用断线钳到直径0.5mm钨棒切成大约25毫米的长度。 </li><li>清洁的丙酮棒在15分钟的超声浴。 </li><li>用去离子水冲洗杆。 </li></ol></li><li> 蚀刻液 注意:NaOH溶液是腐蚀性的碱溶液，NFPA 704标签:可燃性（0），健康（3），不稳定性/反应活性（0），特别（COR） - 和可以引起化学灼伤如果它在与皮肤接触或眼睛。油烟吸入可引起刺激和灼伤呼吸道。当处理NaOH溶液，WEA- [R化学防溅护目镜和面罩来保护眼睛，手套，以保护皮肤围裙。在通风橱中进行蚀刻过程或佩戴呼吸器。护理应执行步骤1.1.3.1时以产生稀释的NaOH溶液作出。这个过程是高度放热的，并且可以释放可导致烧伤或点燃易燃，并且可能导致溶液飞溅出容器的热量。 <ol><li>通过重量NaOH溶液370毫升去离子水加入30ml的50％相结合，使的400ml总体积进行的1.5M NaOH溶液。 </li><li>填充该NaOH溶液的分液漏斗。 </li></ol></li><li> 切断电路 注意:如果直流电源是手动操作，那么运营商将关闭电源关闭，一旦钨棒已经蚀刻一路过关斩将（参见1.2.2）。在手工操作的情况下，跳到步骤1.2。对于直流电源自动切断，所示的切断电路（&lt;强&gt;图2和以下描述）时，应构成。在这里，我们实现了使用数据采集卡的计算机控制。 <ol><li>与直流电源串联一个电流表。 </li><li>并联的两个电阻器，R 1和R 2串联和地点与电路的钨棒/反电极的蚀刻腿。 （对于R 1和R 2标称值分别为R 1 = 5kΩ和R 2 = 10千欧）。 </li><li>监视横跨与模拟-数字转换器（ADC）和合适的计算机控制软件，例如 LabVIEW中的电阻器之一的电压。所监视的电压V 纹 ，可与在这两个电阻器，因此电压，经由穿过蚀刻腿，V 蚀刻的电压， （4） <img alt="19式" src="/files/ftp_upload/54030/54030eq19.jpg" /> ， W¯¯这里的电压被R两端1监视。 </li><li>连接的低电阻电阻器，R L = 1Ω，串联在蚀刻电路。使用的ADC的第二通道，记录电阻两端的电压。然后蚀刻电流通过发现我 蚀刻 ≈V L / R L。 （仅约1mA流动扔了电路的监控站。） </li><li>在软件中，创建一个程序，以输出从数字输入/输出通道（DI / O）为5 V TTL信号或者当超过设定值的蚀刻电压升高，或低于设定值的蚀刻电流下降，表明钨棒经历蚀刻一路。这些值依赖于腐蚀电流和NaOH溶液的摩尔浓度被使用，并应与该实验的测试运行来确定。 </li><li> 如图2中所示，安排5伏TTL信号邻笔继电器停止电流。 </li></ol></li></ol></li></ol><img alt="图2" src="/files/ftp_upload/54030/54030fig2.jpg" /> 图2示意图蚀刻的电路。在蚀刻电路的示意图用于提供恒定的DC蚀刻电流。电流是通过监视的低电阻电阻器的电压确定，并且电压是通过使用一个ADC跨越高电阻电阻器监视电压记录。一种计算机程序，监视当前并提供5 V输出信号打开的蚀刻电路一旦低于规定值的电流下降的继电器。 <a href="https://www.jove.com/files/ftp_upload/54030/54030fig2large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> <ol start="2"><li> 蚀刻过程 <ol><li> 设备的准备 <ol><li>建立appar的ATU 如图1，用设置在宽基底玻璃烧杯中，并位于其上方的阴极铜内的铜的FEP捕手块，通过绝缘支座间隔开关。 </li><li>设置在DC电源的电流为所需的值，一般为200毫安。 </li><li>放置一个钨棒在支架和鳄鱼夹连接直流电源到4-40夹持螺钉的正极端子。 </li><li>通过在铜阴极的孔插入钨棒，使得约12毫米的钨棒的穿过孔。 </li><li>电源的负极端子连接到与另一个鳄鱼夹在铜阴极。 </li></ol></li><li> 蚀刻 <ol><li>手动调节分液漏斗的滴速通过孔相匹配的滴速，大约每3秒滴注。等待中的阴极铜水库变满。 </li><li>打开直流电源到begin蚀刻。 </li><li>如果在手动模式下操作，关闭直流电源一旦尖端的底部蚀刻一路通过和下降。如果与自动关闭开关操作，蚀刻电流就会被自动切断，一旦杆蚀刻通过。 </li></ol></li></ol></li></ol> 2.场发射点的表征<ol><li> 提示检查 <ol><li>小心地从捕手块用钳子镊子或尖底。松开螺丝4-40，并轻轻拉动上提示出用钳子或钳子取下钨棒持有人上部一角。 </li><li>用丙酮，然后用去离子水冲洗。 </li><li>用光学显微镜检查。提示应该被视为汇聚到细点。那些不这样做， 例如 ，因为它们被弯曲或不具有规则的锥体结构中，应该被丢弃。 图3示出的例子（一）良好的尖端和（b）的弯曲尖端。 </li><li>提示储存在干燥器中。 </li></ol></li></ol><img alt="图3" src="/files/ftp_upload/54030/54030fig3.jpg" /> 图3. FEP提示的光学图像。（ 一 ）一个很好的提示和（b）一个坏的提示，通过光学显微镜观察。图片<a href="https://www.jove.com/files/ftp_upload/54030/54030fig3large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> <ol start="2"><li> 扫描电子显微镜（SEM）成像 <ol><li>用于SEM成像，安全FEP提示，以导电夹持器使用导电带或由它们拧到它（ 例如 ， 见图4）和图像中的扫描电镜，根据制造商的在约1,800X和37,000X的放大倍率的协议，以查看的锥尖端和尖端的端部，分别</li></ol></li> &lt;/ OL&gt; <img alt="图4" src="/files/ftp_upload/54030/54030fig4.jpg" /> 图的SEM图像4. FEP持有者。（A）的顶部和的图片（二）用于紧固前置机同时用扫描电镜成像，在支架底部<a href="https://www.jove.com/files/ftp_upload/54030/54030fig4large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> <img alt="图5" src="/files/ftp_upload/54030/54030fig5.jpg" /> 图5.场发射装置。示意图装置用于将高压施加到前置机同时在真空下，以产生电子束。电子束电流法拉第杯具皮安表监控。 <a href="https://www.jove.com/files/ftp_upload/54030/54030fig5large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> <ol start="3"><li><stroNG&gt;场发射测试<ol><li> 仪器 注意:对于场发射测试以下，或类似的，设备是必需的:6路6"conflat法兰跨作为一个真空室，3个6"到2¾"conflat法兰零长度适配器，一个SHV（安全在2¾高电压）馈通"conflat法兰，一个BNC馈通在2¾"conflat法兰，在2¾线性馈通"conflat法兰，一个6"conflat法兰窗，6"conflat凸缘坯料休，涡轮真空泵安装到6"conflat凸缘，和一个后备泵（ 例如，涡旋泵）的涡轮，一个高压（HV）电源能够提供高达-5千伏供给需要偏压FEP，和一个皮安计需要监测来自FEP发射并收集在法拉第杯电子流，参见例如，13，在代替法拉第杯的，可以使用一个简单的导电收集板，一个schemati的场致发射建立的c为示出在图5中。 <ol><li>制作第二钨棒持有人（见步骤1.1.1.1）。在支架的另一端与前置机钻一个直径为1毫米的孔钻和挖掘杆侧面的孔4-40螺丝将其固定到SHV引线的真空侧。 </li><li>设置的场致发射装置， 如图5所示。法拉第杯应该从FEP的端部大约2厘米。 </li><li>连接高压供给到该FEP保持器附连到SHV馈通，以及连接皮安计到法拉第杯连接到BNC馈通。 </li><li>抽空的设置多达10个的压力- 6毫巴或更低。 </li></ol></li><li> 场发射 <ol><li>逐步加大对FEP的偏见和显示器上的法拉第杯电子束电流以皮安表。当场发射开始时，一个电流将被观察皮安表。 </li><li>增加在增量步骤（大约50伏特）的HV和记录在每一步皮安计的平均电子束电流。 （如果需要的话，也可以手动完成这一过程可以是计算机控制的例如由LabVIEW程序）。保持低于1μA电子束电流。 </li></ol></li><li>空调<ol><li>通过场发射模式下5 nA的1小时工作状态提示。 </li><li>重复播放当前VS的2.3.2.2 HV扫描。 </li></ol></li></ol></li></ol>

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The authors have nothing to disclose.

我们已经描述了简单的程序，以在一个NaOH溶液电化学蚀刻尖锐场发射点（前置机），并通过场发射模式操作它们来测试前置机。所描述的蚀刻过程是现有技术-薄片下车技术7,8和浮动层技术9,10的变化。但是，我们发现这是更加方便和可靠比上述的方法来实现。 在开始蚀刻过程，以最小化生产具有毛的变形， 例如，一个弯曲的末端，如在图2...

尖锐尖端或点已长期显微镜应用，如场离子显微镜（FIM）1和扫描隧道显微镜（STM）2，和一系列的用于制造各种材料的尖锐尖端技术中使用已开发了3。这些尖头还可以通过施加高电压，以它们作为场致发射点（前置机）动作，并作为一个方便的电子束源。如源的一个应用是通过电子轰击电离（EII）离子的生产。该FEP是在由热发射体产生的温度波动是不期望的应用中是特别有利的。例如，通过背景气体或蒸气的EII离子生产高精度潘宁陷阱4,5。 用于制造前置机一个简单的方法是电化学蚀刻钨棒在氢氧化钠（NaOH）溶液。这种技术相对简单，以便实现具有适度的设备，并已被证明是相当重复，可靠。许多方法在文献中有描述和改进这些技术继续出现6。在这里，我们描述了钨提示在NaOH溶液中电化学腐蚀的方法。我们的方法是片晶落客技术7,8的变化和浮层技术9,10。这两种方法，如它能够生产的从单个蚀刻过程两个尖端。用于蚀刻的尖端的实验装置的图象示于图1。 <img alt="图1" src="/files/ftp_upload/54030/54030fig1.jpg" /> 图1.蚀刻设备。用于钨棒用NaOH溶液的电化学蚀刻的实验装置的照片。 <a href="https://www.jove.com/files/ftp_upload/54030/54030fig1large.jpg" target="_blank">请</a>此处查看该图的放大版本。 在NaOH水溶液碱钨的电化学蚀刻经由一个两阶段过程中发生。首先，中间氧化钨形成​​，并且第二，这些氧化物是非电化学溶解形成可溶性钨阴离子。这个过程的描述，以简化形式，由两个反应 （1）W + 6OH - →WO 3（s）+ 3H 2 O + 6e中- ，和 （2）WO 3（s）+ 2OH - →WO 4 2- + H 2 O 蚀刻电流和所用的NaOH溶液的摩尔浓度影响通过钨棒以蚀刻所需要的时间和电压。在这些效应的研究介绍和讨论。更重要的是，蚀刻参数有场发射模式上的提示的几何形状，并且作为这样的效果，对它们的操作。的几何<html>通过将它们与扫描型电子显微镜（SEM）成像，我们产生的提示进行了表征。这些图像可以被用来估计，例如，尖端半径。此外，该提示是在场致发射模式通过施加通常几百伏的负电压到几千伏给他们，并监测所产生的电子发射电流。场致发射电流之间的关系，I和施加的偏置电压V，可以通过福勒-诺德海姆方程11所描述 （3）I = AV 2ë-Cr EFF / V， 其中r eff是尖的有效半径，A是常数，C是所述第二福勒-诺德海姆恒定<img alt="公式9" src="/files/ftp_upload/54030/54030eq9.jpg" /> ，其中B = 6.83 eV的- 3/2 V /纳米，030eq11.jpg"/&gt;是钨的功函数（ <img alt="11式" src="/files/ftp_upload/54030/54030eq11.jpg" /> ≈4.5电子伏特），k为取决于几何因素（K≈5），和<img alt="12式" src="/files/ftp_upload/54030/54030eq15.jpg" />是诺德海姆图像校正项（ <img alt="12式" src="/files/ftp_upload/54030/54030eq15.jpg" /> ≈1）12。因此，前端的有效半径可以通过测量电子电流作为偏置电压的函数来确定。具体地，它可以从LN的一个所谓的福勒-诺德海姆（FN）情节（I / V 2）与1 / V的斜率来获得。

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			<td height="20" style="height:20px;width:325px;">Tungsten Rod 0.020&#34; x 12&#34;</td>
			<td style="width:159px;">ESPI Metals</td>
			<td style="width:451px;"><a href="http://www.espimetals.com/index.php/online-catalog/467-Tungsten">http://www.espimetals.com/index.php/online-catalog/467-Tungsten&#160;</a></td>
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			<td height="20" style="height:20px;">NaOH salt</td>
			<td>Cole-Parmer</td>
			<td>Item # WU-88404-71</td>
			<td>100 g</td>
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		<tr height="20">
			<td height="20" style="height:20px;">Separatory funnel</td>
			<td>Cole-Parmer</td>
			<td>Item#&#160;WU-34506-03</td>
			<td>250 mL&#160;</td>
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			<td>BK Precision</td>
			<td>1672</td>
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			<td height="20" style="height:20px;">Acetone</td>
			<td>Cole-Parmer</td>
			<td>Item#&#160;WU-88000-68</td>
			<td>500 mL</td>
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			<td height="20" style="height:20px;">Data Acquisition Card</td>
			<td>National Instruments</td>
			<td style="width:451px;">NI PXI-6221</td>
			<td>16 AI, 24 DIO, 2 AO</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Relay</td>
			<td>Magnecraft</td>
			<td>276 XAXH-5D</td>
			<td>7 A, 30 V DC Reed Relay</td>
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			<td>Kurt J Lesker</td>
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			<td height="20" style="height:20px;">6&#34; to 2-3/4&#34; conflat zero length reducer flange&#160; (x3)</td>
			<td>Kurt J Lesker</td>
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			<td>Kurt J Lesker</td>
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			<td>Kurt J Lesker</td>
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			<td>MDC</td>
			<td>660006, REF# BLM-275-2</td>
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			<td>Kurt J Lesker</td>
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			<td>Keithley Instruments</td>
			<td>Keithley Model #2290-5</td>
			<td>0 - 5 kV DC HV Power Supply</td>
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			<td height="20" style="height:20px;">Picoammeter</td>
			<td>Keithley Instruments</td>
			<td>Keithley Model #6485</td>
			<td></td>
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		<tr height="20">
			<td height="20" style="height:20px;">Faraday Cup</td>
			<td>Beam Imaging Solutions</td>
			<td>Model FC-1 Faraday Cup</td>
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	</tbody>
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electrochemical etching and characterization of sharp field emission points for electron impact ionization

A new variation of the drop-off method for fabricating field emission points by electrochemically etching tungsten rods in a NaOH solution is described. The results of studies in which the etching current and the molarity of the NaOH solution used in the etching process were varied are presented. The investigation of the geometry of the tips, by imaging them with a scanning electron microscope, and by operating them in field emission mode is also described. The field emission tips produced are intended to be used as an electron beam source for ion production via electron impact ionization of background gas or vapor in Penning trap mass spectrometry applications.

研究腐蚀参数 在蚀刻工艺期间的电源是恒流模式操作。所需的电压作为钨棒蚀刻掉（由于在杆的阻力的增加），以略微保持这个恒定电流增大。目前几乎降到零当尖端通过蚀刻一路。一个小的电流继续由于流动的事实，上部前端仍然与蚀刻溶液接触。的电流和电压作为蚀刻工艺期间作为时间函数作图示于图...

Watch this Scientific Journal Video about Electrochemical Etching and Characterization of Sharp Field Emission Points for Electron Impact Ionization at JoVE.com

Electrochemical Etching and Characterization of Sharp Field Emission Points for Electron Impact Ionization

A method for electrochemically etching field emission tips is presented. Etching parameters are characterized and the operation of the tips in field emission mode is investigated.

电化学腐蚀和电子碰撞电离夏普场发射点的表征

A new variation of the drop-off method for fabricating field emission points by electrochemically etching tungsten rods in a NaOH solution is described. ...

electrochemical-etching-characterization-sharp-field-emission-points

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9.4K 次观看.  Central Michigan University. A method for electrochemically etching field emission tips is presented. Etching parameters are characterized and the operation of the tips in field emission mode is investigated.

视频: Electrochemical Etching and Characterization of Sharp Field Emission Points for Electron Impact Ionization

Fabrication of VB2/Air Cells for Electrochemical Testing

A technique to investigate the properties and performance of new multi-electron metal/air battery systems is proposed and presented. A method for synthesizing nanoscopic VB2 is presented as well as step-by-step procedure for applying a zirconium oxide coating to the VB2 particles for stabilization upon discharge. The process for disassembling existing zinc/air cells is shown, in addition construction of the new working electrode to replace the conventional zinc/air cell anode with a the nanoscopic VB2 anode. Finally, discharge of the completed VB2/air battery is reported. We show that using the zinc/air cell as a test bed is useful to provide a consistent configuration to study the performance of the high-energy high capacity nanoscopic VB2 anode.

Fabrication of VB2/Air Cells for Electrochemical Testing

A protocol is presented to study multi-electron metal/air battery systems by using previous technology developed for the zinc/air cell. Electrochemical testing is then performed on fabricated batteries to evaluate performance.

VB制作<sub&gt; 2</sub&gt; /空气电池电化学测试

A technique to investigate the properties and performance of new multi-electron metal/air battery systems is proposed and presented. A method for ...

科研

工程学

Spatial Separation of Molecular Conformers and Clusters

Gas-phase molecular physics and physical chemistry experiments commonly use supersonic expansions through pulsed valves for the production of cold molecular beams. However, these beams often contain multiple conformers and clusters, even at low rotational temperatures. We present an experimental methodology that allows the spatial separation of these constituent parts of a molecular beam expansion. Using an electric deflector the beam is separated by its mass-to-dipole moment ratio, analogous to a bender or an electric sector mass spectrometer spatially dispersing charged molecules on the basis of their mass-to-charge ratio. This deflector exploits the Stark effect in an inhomogeneous electric field and allows the separation of individual species of polar neutral molecules and clusters. It furthermore allows the selection of the coldest part of a molecular beam, as low-energy rotational quantum states generally experience the largest deflection. Different structural isomers (conformers) of a species can be separated due to the different arrangement of functional groups, which leads to distinct dipole moments. These are exploited by the electrostatic deflector for the production of a conformationally pure sample from a molecular beam. Similarly, specific cluster stoichiometries can be selected, as the mass and dipole moment of a given cluster depends on the degree of solvation around the parent molecule. This allows experiments on specific cluster sizes and structures, enabling the systematic study of solvation of neutral molecules.

We present a technique that allows the spatial separation of different conformers or clusters present in a molecular beam. An electrostatic deflector is used to separate species by their mass-to-dipole moment ratio, leading to the production of gas-phase ensembles of a single conformer or cluster stoichiometry.

分子构象器和星团的空间分离

Gas-phase molecular physics and physical chemistry experiments commonly use supersonic expansions through pulsed valves for the production of cold ...

Characterization of Recombination Effects in a Liquid Ionization Chamber Used for the Dosimetry of a Radiosurgical Accelerator

Most modern radiation therapy devices allow the use of very small fields, either through beamlets in Intensity-Modulated Radiation Therapy (IMRT) or via stereotactic radiotherapy where positioning accuracy allows delivering very high doses per fraction in a small volume of the patient. Dosimetric measurements on medical accelerators are conventionally realized using air-filled ionization chambers. However, in small beams these are subject to nonnegligible perturbation effects. This study focuses on liquid ionization chambers, which offer advantages in terms of spatial resolution and low fluence perturbation. Ion recombination effects are investigated for the microLion detector (PTW) used with the Cyberknife system (Accuray). The method consists of performing a series of water tank measurements at different source-surface distances, and applying corrections to the liquid detector readings based on simultaneous gaseous detector measurements. This approach facilitates isolating the recombination effects arising from the high density of the liquid sensitive medium and obtaining correction factors to apply to the detector readings. The main difficulty resides in achieving a sufficient level of accuracy in the setup to be able to detect small changes in the chamber response.

A growing number of radiation therapy devices offer the advantage of delivering the dose through very small beams to the tumor, allowing for increased conformity and higher doses per fraction. Many different detectors can be used for the dosimetry of these small fields. In the present study, the effect of ion recombination is investigated for a liquid ionization chamber using a stereotactic radiation therapy system.

重组的影响在液体电离室表征用于一个电波加速器的剂量学

Most modern radiation therapy devices allow the use of very small fields, either through beamlets in Intensity-Modulated Radiation Therapy (IMRT) or via ...

Electron Channeling Contrast Imaging for Rapid III-V Heteroepitaxial Characterization

Misfit dislocations in heteroepitaxial layers of GaP grown on Si(001) substrates are characterized through use of electron channeling contrast imaging (ECCI) in a scanning electron microscope (SEM). ECCI allows for imaging of defects and crystallographic features under specific diffraction conditions, similar to that possible via plan-view transmission electron microscopy (PV-TEM). A particular advantage of the ECCI technique is that it requires little to no sample preparation, and indeed can use large area, as-produced samples, making it a considerably higher throughput characterization method than TEM. Similar to TEM, different diffraction conditions can be obtained with ECCI by tilting and rotating the sample in the SEM. This capability enables the selective imaging of specific defects, such as misfit dislocations at the GaP/Si interface, with high contrast levels, which are determined by the standard invisibility criteria. An example application of this technique is described wherein ECCI imaging is used to determine the critical thickness for dislocation nucleation for GaP-on-Si by imaging a range of samples with various GaP epilayer thicknesses. Examples of ECCI micrographs of additional defect types, including threading dislocations and a stacking fault, are provided as demonstration of its broad, TEM-like applicability. Ultimately, the combination of TEM-like capabilities &#8211; high spatial resolution and richness of microstructural data &#8211; with the convenience and speed of SEM, position ECCI as a powerful tool for the rapid characterization of crystalline materials.

The use of electron channeling contrast imaging in a scanning electron microscope to characterize defects in III-V/Si heteroexpitaxial thin films is described. This method yields similar results to plan-view transmission electron microscopy, but in significantly less time due to lack of required sample preparation.

电子通道造影的快速III-V异质特征

Misfit dislocations in heteroepitaxial layers of GaP grown on Si(001) substrates are characterized through use of electron channeling contrast imaging ...

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 ...

Emission Spectroscopic Boundary Layer Investigation during Ablative Material Testing in Plasmatron

Ablative Thermal Protection Systems (TPS) allowed the first humans to safely return to Earth from the moon and are still considered as the only solution for future high-speed reentry missions. But despite the advancements made since Apollo, heat flux prediction remains an imperfect science and engineers resort to safety factors to determine the TPS thickness. This goes at the expense of embarked payload, hampering, for example, sample return missions. 
Ground testing in plasma wind-tunnels is currently the only affordable possibility for both material qualification and validation of material response codes. The subsonic 1.2MW Inductively Coupled Plasmatron facility at the von Karman Institute for Fluid Dynamics is able to reproduce a wide range of reentry environments. This protocol describes a procedure for the study of the gas/surface interaction on ablative materials in high enthalpy flows and presents sample results of a non-pyrolyzing, ablating carbon fiber precursor. With this publication, the authors envisage the definition of a standard procedure, facilitating comparison with other laboratories and contributing to ongoing efforts to improve heat shield reliability and reduce design uncertainties.
The described core techniques are non-intrusive methods to track the material recession with a high-speed camera along with the chemistry in the reactive boundary layer, probed by emission spectroscopy. Although optical emission spectroscopy is limited to line-of-sight measurements and is further constrained to electronically excited atoms and molecules, its simplicity and broad applicability still make it the technique of choice for analysis of the reactive boundary layer. Recession of the ablating sample further requires that the distance of the measurement location with respect to the surface is known at all times during the experiment. Calibration of the optical system of the applied three spectrometers allowed quantitative comparison. At the fiber scale, results from a post-test microscopy analysis are presented.

Development of new ablative materials and their numerical modeling requires extensive experimental investigation. This protocol describes procedures for material response characterization in plasma flows with the core techniques being non-intrusive methods to track the material recession along with the chemistry in the reactive boundary layer by emission spectroscopy.

烧蚀材料在试验过程中等离子体发生器发射光谱边界层研究

Ablative Thermal Protection Systems (TPS) allowed the first humans to safely return to Earth from the moon and are still considered as the only solution ...

Comprehensive Characterization of Extended Defects in Semiconductor Materials by a Scanning Electron Microscope

Extended defects such as dislocations and grain boundaries have a strong influence on the performance of microelectronic devices and on other applications of semiconductor materials. However, it is still under debate how the defect structure determines the band structure, and therefore, the recombination behavior of electron-hole pairs responsible for the optical and electrical properties of the extended defects. The present paper is a survey of procedures for the spatially resolved investigation of structural and of physical properties of extended defects in semiconductor materials with a scanning electron microscope (SEM). Representative examples are given for crystalline silicon. The luminescence behavior of extended defects can be investigated by cathodoluminescence (CL) measurements. They are particularly valuable because spectrally and spatially resolved information can be obtained simultaneously. For silicon, with an indirect electronic band structure, CL measurements should be carried out at low temperatures down to 5 K due to the low fraction of radiative recombination processes in comparison to non-radiative transitions at room temperature. For the study of the electrical properties of extended defects, the electron beam induced current (EBIC) technique can be applied. The EBIC image reflects the local distribution of defects due to the increased charge-carrier recombination in their vicinity. The procedure for EBIC investigations is described for measurements at room temperature and at low temperatures. Internal strain fields arising from extended defects can be determined quantitatively by cross-correlation electron backscatter diffraction (ccEBSD). This method is challenging because of the necessary preparation of the sample surface and because of the quality of the diffraction patterns which are recorded during the mapping of the sample. The spatial resolution of the three experimental techniques is compared.

The optical, electrical, and structural properties of dislocations and of grain boundaries in semiconductor materials can be determined by experiments performed in a scanning electron microscope. Electron microscopy has been used to investigate cathodoluminescence, electron beam induced current, and diffraction of backscattered electrons.

通过扫描电子显微镜在半导体材料的扩展缺陷的全面表征

Extended defects such as dislocations and grain boundaries have a strong influence on the performance of microelectronic devices and on other applications ...

Fabrication of White Light-emitting Electrochemical Cells with Stable Emission from Exciplexes

The authors present an approach for fabricating stable white light emission from polymer light-emitting electrochemical cells (PLECs) having an active layer which consists of blue-fluorescent poly(9,9-di-n-dodecylfluorenyl-2,7-diyl) (PFD) and &#960;-conjugated triphenylamine molecules. This white light emission originates from exciplexes formed between PFD and amines in electronically excited states. A device containing PFD, 4,4&#39;,4&#39;&#39;-tris[2-naphthyl(phenyl)amino]triphenylamine (2-TNATA), Poly(ethylene oxide) and K2CF3SO3 showed white light emission with Commission internationale de l&#39;&#233;clairage (CIE) coordinates of (0.33, 0.43) and a Color Rendering Index (CRI) of Ra = 73 at an applied voltage of 3.5 V. Constant voltage measurements showed that the CIE coordinates of (0.27, 0.37), Ra of 67, and the emission color observed immediately after application of a voltage of 5 V were nearly unchanged and stable after 300 sec.

The authors present a method for fabricating stable white-light-emitting electrochemical cells utilizing emission from exciplexes formed between a blue-emitting fluorene polymer and aromatic amines.

白的制造发光电化学细胞与来自激发络合物稳定的发射

The authors present an approach for fabricating stable white light emission from polymer light-emitting electrochemical cells (PLECs) having an active ...

One-Step Approach to Fabricating Polydimethylsiloxane Microfluidic Channels of Different Geometric Sections by Sequential Wet Etching Processes

Polydimethylsiloxane (PDMS) materials are substantially exploited to fabricate microfluidic devices by using soft lithography replica molding techniques. Customized channel layout designs are necessary for specific functions and integrated performance of microfluidic devices in numerous biomedical and chemical applications (e.g., cell culture, biosensing, chemical synthesis, and liquid handling). Owing to the nature of molding approaches using silicon wafers with photoresist layers patterned by photolithography as master molds, the microfluidic channels commonly have regular cross sections of rectangular shapes with identical heights. Typically, channels with multiple heights or different geometric sections are designed to possess particular functions and to perform in various microfluidic applications (e.g., hydrophoresis is used for sorting particles and in continuous flows for separating blood cells6,7,8,9). Therefore, a great deal of effort has been made in constructing channels with various sections through multiple-step approaches like photolithography using several photoresist layers and assembly of different PDMS thin sheets. Nevertheless, such multiple-step approaches usually involve tedious procedures and extensive instrumentation. Furthermore, the fabricated devices may not perform consistently and the resulted experimental data may be unpredictable. Here, a one-step approach is developed for the straightforward fabrication of microfluidic channels with different geometric cross sections through PDMS sequential wet etching processes, that introduces etchant into channels of planned single-layer layouts embedded in PDMS materials. Compared to the existing methods for manufacturing PDMS microfluidic channels with different geometries, the developed one-step approach can significantly simplify the process to fabricate channels with non-rectangular sections or various heights. Consequently, the technique is a way of constructing complex microfluidic channels, which provides a fabrication solution for the advancement of innovative microfluidic systems.

Several methods are available for the fabrication of channels of non-rectangular sections embedded in polydimethylsiloxane microfluidic devices. Most of them involve multistep manufacturing and extensive alignment. In this paper, a one-step approach is reported for fabricating microfluidic channels of different geometric cross sections by polydimethylsiloxane sequential wet etching.

连续湿法刻蚀法制作不同几何断面烷微流控通道的一步法

Polydimethylsiloxane (PDMS) materials are substantially exploited to fabricate microfluidic devices by using soft lithography replica molding techniques. ...

Method Development for Contactless Resonant Cavity Dielectric Spectroscopic Studies of Cellulosic Paper

The current analytical techniques for characterizing printing and graphic arts substrates are largely ex situ and destructive. This limits the amount of data that can be obtained from an individual sample and renders it difficult to produce statistically relevant data for unique and rare materials. Resonant cavity dielectric spectroscopy is a non-destructive, contactless technique which can simultaneously interrogate both sides of a sheeted material and provide measurements which are suitable for statistical interpretations. This offers analysts the ability to quickly discriminate between sheeted materials based on composition and storage history. In this methodology article, we demonstrate how contactless resonant cavity dielectric spectroscopy may be used to differentiate between paper analytes of varying fiber species compositions, to determine the relative age of the paper, and to detect and quantify the amount of post-consumer waste (PCW) recycled fiber content in manufactured office paper.

A protocol for the non-destructive analysis of the fiber content and relative age of paper.

纤维素纸非接触式共振腔电谱研究的方法研究

The current analytical techniques for characterizing printing and graphic arts substrates are largely ex situ and destructive. This limits the amount of ...

电化学腐蚀和电子碰撞电离夏普场发射点的表征

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