这项工作得到了美国陆军研究办公室的 W911NF-14-1-0241 和 W911NF-17-1-0119 奖的支持。DMB 是由美国能源部科学办公室, 基础能源科学办公室在奖编号 DE-FC02-04ER1553。

1. 搭建实验装置
注: 要运行这个实验, 组装一个由等离子体反应器组成的系统, 其中的反应将发生, 光学元件的吸光度测量, 和电子锁定放大系统处理信号。
<ol><li>
构造等离子体电化学电池。
	<ol>
<li>制造一个由透明的玻璃容器组成的反应器单元, 直径50.8 毫米 (2), 两个光学窗口的角度近似°从正常平面向下。</li>
		<li>构造一个含有四孔的非渗透性盖子, 用于介绍等离子电极、铂阳极和用氩 (Ar) 冲洗磁头间隙的小软管。 注意:第四孔将允许 Ar 从头部空间排出。</li>
		<li>通过将一块铂箔贴在不锈钢棒上形成阳极。</li>
		<li>形成阴极通过锐化1.58 毫米 (1/16) 外径的末端, 0.178 毫米 (0.007) 内径不锈钢毛细管。使用适当的接头将 Ar 软管连接到毛细管的钝端。</li>
	</ol>
</li>
	<li>
构造光学测量装置。
	<ol>
<li>构造一个由 670 nm 二极管激光器、可调虹膜和 50 mm 镜头组成的激光光源, 它们都安装在 30 mm 的光笼系统中。将笼装入测, 使整个系统可在19角度旋转, 并将激光定向到电化学电池的一个光学窗口中。 注意:也可以使用其他激光波长, 请参见 Ref 16.</li>
		<li>构造一个由大面积光电二极管连接成反向偏置泄漏电路的光电探测器。将光电探测器安装在测上, 以便它可以通过与激光源相反的电化学电池的光学窗口接收反射光。此外, 安装到探测器的一个带通滤波器对应的激光波长。 注意:在图 1中可以看到光电探测器电路的示意图。对于这样的电路, 输出电压与激光强度成正比。</li>
	</ol>
</li>
	<li>
构造了等离子体开关电路和锁入放大电路。 注:电子元器件包括高压电源、高压开关电路、功能发生器、电压表和锁定放大器。<ol>
<li>连接高压电源, 使其可以在等离子电极和阳极之间施加大约-2.5 伏的直流 (DC) 偏置, 以产生等离子体。</li>
		<li>使用定制的开关电路, 以20赫的载波频率来调制高值和低数值之间的等离子体电流。 注意:电路示意图如图 2所示。高压电源驱动电流通过两个平行连接的镇流器电阻器。当小电流连续流经3ω电阻时, 通过绝缘栅双极结晶体管 (IGBT) 连续切换电流通过220ω。该函数发生器产生20赫驱动频率, 并通过光隔离器连接到 IGBT, 它将高压电源与功能发生器隔离开来。</li>
		<li>集成锁定放大器, 使光电探测器的输出与之连接。 注意:锁在放大器将过滤噪声在20赫波段外面。它的输出, 即吸光度信号的振幅和相位, 应由计算机记录。一个内部程序被用来记录输出。</li>
	</ol>
</li>
</ol>2. 准备次氯酸4溶液作为导电的背景电解质
<ol><li>要准备一个0.163 米次氯酸4解决方案, 这是本实验中使用的浓度, 溶解10克的次氯酸4 500 毫升的去离子水。注意:次氯酸4被选为电解质, 因为它不与溶剂电子发生反应。0.163 m 的集中是仅代表性的, 并且不同的集中可以使用, 典型地在命令 0.001-0. 1 m。</li>
	<li>将60毫升的次氯酸4倒入等离子体反应器。</li>
</ol>3. 准备测量的设置
<ol><li>
准备电化学电池设置和清除反应器。
	<ol>
<li>将阳极通过适当的孔插入非渗透性的盖子。部分淹没在溶液表面下的阳极。</li>
		<li>将等离子电极 (阴极毛细管) 连接到与 Ar 罐连接的质量流量计上, 并通过盖子插入毛细管。悬浮在溶液表面上方大约1-2 毫米的毛细管尖端。使用摄像机测量毛细管和液体表面之间的距离。</li>
		<li>将小软管连接到与 Ar 罐相连的质量流量计, 并将软管插入盖子中的一个孔中;这形成清除线。</li>
		<li>与阴极, 阳极, 和 Ar 清除线到位, 确保非渗透性的盖子的顶部的反应堆细胞。</li>
		<li>通过清除线上的 Ar 流到大约 250 cm3/分钟, 至少5分钟, 从等离子反应器的顶部排出空气。 注意:反应器的流量和流动时间取决于反应器的容积和溶液的体积;这里使用的值是有代表性的。不冲洗空气会导致溶液中溶解氧驱动的副反应 (见 Ref. 21)。</li>
	</ol>
</li>
	<li>
对齐测量。
	<ol>
<li>通过等离子电极将氩气的流量设置为大约10厘米3/分钟, 使反应堆的激光命中等离子-液体界面。这样做是通过观察光被氩气的流动驱散了酒窝。</li>
		<li>关闭氩气到等离子体电极的流动, 等待激光光斑回到其正常尺寸。一旦发生这种情况, 对齐光电探测器, 使激光击中检测器的中心。</li>
	</ol>
</li>
	<li>
测量基线信号强度并准备电气系统。
	<ol>
<li>将光电探测器输出连接到电压表, 并测量激光器所发出的电压。记录这个值, 因为它稍后将被用来规范测量的吸光度信号。 注意:此值与事件强度I0直接成正比。</li>
		<li>在测量入射强度后, 从光电探测器上拔下电缆并将其连接到锁定放大器的输入, 以在20赫载波频率处锁定信号。</li>
		<li>将函数发生器的晶体管-晶体管逻辑输出连接到锁定放大器的频率输入。</li>
		<li>确保打开了锁定放大器、功能发生器和高压电源。 注意:这项实验现在已经准备好开始了。</li>
	</ol>
</li>
</ol>4. 开始实验和数据收集
注意:内部程序用于数据收集。此外, 该系统是自动化的, 以确保精度和减少人为错误。以下步骤介绍了此自动化的底层过程。
<ol><li>打开激光, 开始测量吸光度。让噪音的时间被整合到一个足够低的水平。</li>
	<li>将高压电源设置为大约-2.5 伏的电压差, 以点燃等离子体。 注意:在图 3中显示了从液体表面的距离1毫米的等离子体放电的照片。</li>
	<li>等待约半分钟的振幅测量的锁定放大器达到一个稳定状态, 并在此之后, 记录信号约2分钟。</li>
	<li>关闭激光器, 等待激光信号到达稳定状态。随后, 测量半分钟的吸光度。 注意:这种测量将从以前的吸光度测量中减去, 以解释来自等离子体的噪声。</li>
	<li>关闭高压电源, 关掉等离子。</li>
	<li>要重复实验, 确保等离子电极仍然是对齐的。为此, 应收回至少1厘米的等离子电极, 然后通过毛细管打开 Ar 流。重复步骤3.2 到4.5。</li>
	<li>如果没有更多的实验将被重复, 关闭所有的电子仪器, 从电化学电池中脱下盖子, 并适当地处理次氯酸4 。</li>
</ol>5. 数据分析
注意:从锁定放大器的输出包含有关 20 kHz 吸光度信号的振幅R和相位ϕ的信息。这可以分别由余弦和正弦分量、 X和Y表示。由于锁定放大器测量在步骤1.3.2 中设置的高低电流之间信号的调制幅度, 所以X和Y表示这两个信号之间的差异, 并用于测量吸光度的差异在低和高状态之间, ΔI。
<ol><li>若要正确分析数据, 请通过将事件强度电压I0除以它们来规范化X和Y时间向量。 注意:这一电压, 这是在步骤3.3.1 测量, 是直接成正比的光学强度, 是信号组件X和Y。因此, 将X和Y除以该值应产生无量纲向量, 表示 20 kHz 吸收信号中的相和外相位分量。</li>
	<li>获取X/i0 和Y/i0 从当等离子体打开直到激光器关闭时的稳定状态。 注意:图 4显示了在整个实验中测量的归一化吸收 RMS 大小R 。血浆在三十年代以后被交换了, 吸光度信号在五十年代的时间到达了稳态, 并且血浆在150s 时被关闭了。</li>
	<li>同样, 从激光关闭直到等离子体被关闭以获得等离子体噪声的余弦和正弦分量的那一刻起, 获取X/i0 和Y/i0 的平均值。注意:在图 4中, 等离子体在150s 时被关闭, 噪声测量是从170s 到200s 的平均吸光度。</li>
	<li>为了获得吸收信号的余弦和正弦分量, 从5.2 中获得的平均值减去步骤5.3 中获得的平均值。</li>
	<li>要计算真正的吸光度, 请计算在步骤5.4 中获得的信号的 X 和 Y 分量的平方和, 如公式 1中所示。 <img alt="Equation 1" src="/files/ftp_upload/56833/56833eq1v5.jpg">(1)</li>
</ol>6. 参数提取
<ol><li>计算溶剂电子在溶液中的浓度, 假设溶剂电子被等离子体引入溶液的速率与它们被消耗的速率之间的稳态状态。 注意:在没有其他反应的情况下, 溶剂电子的消耗是通过电子的二阶复合来产生的, 如方程式 2所示。 <img alt="Equation 2" src="/files/ftp_upload/56833/56833eq2v7.jpg">(2)<ol>
<li>使用啤酒定律, 如方程式 3所示, 以确定溶剂电子的浓度为未知穿透深度的函数l, 其中ε是摩尔消光系数, θ是入射角 (在步骤中定义为 19)1.2)。 注意:溶剂电子的消光系数为 ~ 1.9万 L 摩尔-1 cm-1 , 如 Ref. 18 所述。 <img alt="Equation 3" src="/files/ftp_upload/56833/56833eq3v5.jpg">(3)</li>
		<li>若要推断未知穿透深度, 请将公式 3与公式 4相结合, 这将假定电子以与等离子体的电流密度成正比的速率引入, 其中k是第二个的反应常数顺序重组, q是基本电荷, j是当前密度, NA是德罗的数字。 注意:公式 4中包含的系数为 2, 表示两个电子在公式 2中的反应被消耗。 <img alt="Equation 4" src="/files/ftp_upload/56833/56833eq4v5.jpg">(4) 穿透长度l和浓度 [(e-)蒽醌] 可以通过使用公式3和 4测量的信号来确定。</li>
	</ol>
</li>
</ol>7. 反应速率估计
注意:当电子在溶液中化不电解质如次氯酸4时, 溶剂的电子只被在等式 2中的反应所消耗。然而, 溶剂电子有能力减少各种各样的阳离子, 阴离子和中性种类。当这些电子清道夫在水溶液中溶解时, 它们会与溶剂电子发生反应。这降低了它们的平衡浓度, 并导致检测到的吸光度降低, 这使得拉斯方法能够估计这些反应的反应速率常数。当一个新的反应被引入, 利率平衡成为: <img alt="Equation 5" src="/files/ftp_upload/56833/56833eq5v5.jpg">(5) 其中 [(S)蒽醌] 是溶液中电子清道夫的浓度, 而 k2是与其反应相关的反应速率常数。但是, 如果清除剂浓度足够大, 则可以将公式 5简化为: 
 <img alt="Equation 6" src="/files/ftp_upload/56833/56833eq6v5.jpg">(6) 公式 3可以与公式 6相结合, 以获得吸光度和清除剂浓度之间的关系。 <img alt="Equation 7" src="/files/ftp_upload/56833/56833eq7v5.jpg">(7)
<ol><li>要用电子清道夫来测量溶剂电子的反应速率常数, 从在步骤1中准备的次氯酸4溶液中溶解清除剂开始。 注意:该解决方案中的非反应次氯酸4确保了足够高的解决方案电导率以保证等离子体的稳定性。清除剂的浓度应该高到足以与二阶重组竞争, 否则, 反应就不会发生。</li>
	<li>重复步骤2.2 到6.1.2 不同的清除剂浓度, 并测量在步骤5.5 中计算的吸光度的差异, 关于纯次氯酸4解决方案。</li>
	<li>将吸光度的图形绘制为 [(S)蒽醌]-1的函数。 注意:如果清除剂浓度足够大,公式 6有效, 则将吸收率绘制为 [(S)蒽醌]-1的函数将产生一条直线, 其斜率取决于速率常数k2。</li>
	<li>从直线的斜率推断反应速率常数 k2 。 注意:有关其他详细信息, 以及如何将其应用于没有2-(蒽醌)的反应的示例, 没有3-(蒽醌)和 H2O2 (蒽醌), CO2 (蒽醌) 与溶剂电子, 参见 Ref. 1619。</li>
</ol>

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J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+effect+of+solvent+and+of+solutes+on+the+absorption+spectrum+of+solvated+electrons.">The effect of solvent and of solutes on the absorption spectrum of solvated electrons.</a> J. Phys. Chem. 69 (4), 1244-1247 (1965).</li><li>Buxton, G. V., Greenstock, C. L., Helman, W. P., Ross, A. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Critical+review+of+rate+constants+for+reactions+of+hydrated+electrons,+hydrogen+atoms+and+hydroxyl+radicals+(&#183;OH/&#183;O-)+in+aqueous+solution.">Critical review of rate constants for reactions of hydrated electrons, hydrogen atoms and hydroxyl radicals (&#183;OH/&#183;O-) in aqueous solution.</a> J. Phys. Chem. Ref. Data. 17 (2), 513-886 (1988).</li><li>Rumbach, P., Xu, R., Go, D. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electrochemical+production+of+oxalate+and+formate+from+CO2+by+solvated+electrons+produced+using+an+atmospheric-pressure+plasma.">Electrochemical production of oxalate and formate from CO2 by solvated electrons produced using an atmospheric-pressure plasma.</a> J. Electrochem. Soc. 163 (10), 1157-1161 (2016).</li><li>Rumbach, P., Bartels, D. M., Sankaran, R. M., Go, D. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+effect+of+air+on+solvated+electron+chemistry+at+a+plasma/liquid+interface.">The effect of air on solvated electron chemistry at a plasma/liquid interface.</a> J. Phys. D: Appl. Phys. 48 (42), (2015).</li><li>Rumbach, P., Witzke, M., Sankaran, R. 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作者没有什么可透露的。

结果表明, 在等离子体-液界面上测量光的吸光度是检测和测量水溶液中等离子体-溶剂电子浓度的有效方法。随后在不同波长上的测量结果在吸收谱的测量。虽然这个实验是在一个水次氯酸的4溶液中进行的, 但如果电子能在液体中化, 那么这种方法应该对其他种类的液体有效。
次氯酸4解决方案的一个有用的实验特性是, 次氯酸4与溶剂电子无反应。了解?...

等离子体-液体相互作用是等离子体科学和工程界越来越感兴趣的领域。等离子体与液体之间的复杂界面, 含有多种高活性自由基, 在分析化学、等离子体医学、水和废水处理、纳米材料合成等领域有广泛的应用.1,2,3,4,5,6。虽然有各种配置, 可以用来带来与液体7接触的等离子体, 也许最简单的是电解电池的等离子模拟, 其中一个标准金属电极被等离子体或气体放电所取代8. 等离子体电化学电池由反应堆容器、浸入式金属电极和等离子体放电组成, 它可以作为阴极或阳极 (或两者) 的作用。当等离子体放电被用作阴极时, 等离子体中产生的气相电子被注入溶液中。电子进入溶液后, 它们的动能在飞9,10,11的时间尺度上消散, 主要通过非弹性散射的溶剂分子。一旦电子达到了接近热的动能, 它们就会在周围的溶剂分子形成的空穴中捕获和化。根据溶剂和温度, 这些 "溶剂" 电子可能是稳定的, 直到他们与一些可还原的物种在解决方案或与另一个溶剂电子的反应。在水溶液中, 溶剂电子也被称为水合电子12。
这种溶剂的过程早已为人所知, 并从二十世纪六十年代13,14,15, 研究了由脉冲辐或闪光光解等过程产生的水合电子的检测。在传统的辐和光解中, 溶剂电子通过溶剂分子的电离产生;然而, 电子溶剂在血浆-液体接口被注射从气体血浆16。先前的实验已经确定水合电子吸收红光近 700 nm13,14,17, 这使得它们可以通过光学吸收光谱进行实验研究。其他的实验已经测量了它们的扩散常数, 它们的反应速率与数以百计的化学种类, 它们的回转半径, 以及它们的电荷移动性, 以及其他感兴趣的属性12,18。
在文献中, 报告了几种检测溶剂电子的方法, 主要分为两类: 体积剂量法, 其中溶剂电子存在是从其反应产物的大宗化学分析中推断出来的,直接瞬态吸收光谱法, 当反应发生时, 电子的吸收量被测量。后一类, 这里提出的方法是基于, 具有直接和即时证据的优势, 以及监测中间反应的能力。
全内反射吸收谱 (拉斯) 方法的发展背后的基本原理是直接研究溶剂电子在等离子体-液体界面上的作用。反射几何的选择, 因为生产溶剂电子使用等离子体放电, 而不是方法, 如辐或光解, 发生在界面之间的等离子体和液体。当探针激光在入射的浅角度吃表面时, 它被完全反射回溶液中, 并输出到探测器中, 减少了电子吸收的少量光。由于没有光进入等离子体, 实验技术只测量液相中的自由基, 就在界面下方, 因此是一种高度敏感的界面检测技术。此外, 总的内部反射现象具有消除噪声的优点, 即由于表面起伏而引起的部分反射的变化, 从而导致信号的控制。
本文概述的拉斯协议具有三基本特性。第一种是等离子体电化学电池, 它由一个透明的玻璃烧杯组成, 它由两个光学窗口构成, 在大约°朝下的角度和氩气的控制顶部。第二个特性是光学测量系统, 它包括二极管激光器、光笼和光电二极管探测器。激光器提供被溶剂电子吸收的光, 并安装在一个可调节的虹膜和一个光学笼中的 50 mm 透镜上。这种安排是安装在一个测, 使它可以旋转到一个预期的入射角。然后由光电探测器测量透射光的强度, 它由在反向偏置泄漏电路中有线的大面积光电二极管组成。最后, 由于他们的高反应性, 溶剂电子只击穿 ~ 10 毫微米入解答, 产生极小的光学吸收信号的 ~ 10-5光学密度。为了保证一个足够高的信噪比, 第三要素是一个锁定放大系统, 其中包括一个等离子开关电路和一个锁定放大器。在开关电路中, 固态继电器电路在由函数发生器设定的20赫的载波频率上调节高和低值之间的等离子体电流。这反过来也调节了界面的溶剂电子浓度及其光学吸收。锁在放大器然后采取信号从光电探测器并且过滤所有噪声在载波频率外面。
在等离子体-液体实验中, 特别是在等离子体电化学中, 拉斯方法有很大的潜力来揭示重要的化学过程。还原和氧化途径主要是由在等离子体-液体界面上的各种短寿命的自由基驱动的, 而对这些物种的检测对于了解界面化学是极其重要的。拉斯的原位监视功能将有助于建立对等离子体-液体界面所涉及的重要电子驱动反应的更深入的了解。拉斯, 例如, 使测量的反应率可能存在的电子清道夫。以前的研究重点是减少没有2-(蒽醌), 没有3-(蒽醌)和 H2O2 (蒽醌)清除剂溶解在水溶液16, 以及减少溶解CO2 (蒽醌)19。其他研究的重点是等离子体载体气体对等离子体-溶剂电子化学的影响20。

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			<td style="width:144px;">Protek</td>
			<td style="width:144px;">B8055</td>
			<td style="width:144px;"></td>
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			<td height="37" style="height:37px;width:144px;">Lock-in Amplifier</td>
			<td style="width:144px;">Stanford Research Systems</td>
			<td style="width:144px;">SR830</td>
			<td style="width:144px;"></td>
		</tr>
		<tr height="37">
			<td height="37" style="height:37px;width:144px;">High-Voltage Power Supply</td>
			<td style="width:144px;">Stanford Research Systems</td>
			<td style="width:144px;">PS325</td>
			<td style="width:144px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:144px;">Photodetector</td>
			<td style="width:144px;">Self-built</td>
			<td style="width:144px;"></td>
			<td style="width:144px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:144px;">Flowmeter</td>
			<td style="width:144px;">Key Instruments</td>
			<td style="width:144px;">60310 R5</td>
			<td style="width:144px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:144px;">Flow controller</td>
			<td style="width:144px;">Omega Engineering</td>
			<td style="width:144px;">FMA 5400A/5500A</td>
			<td style="width:144px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:144px;">Camera</td>
			<td style="width:144px;">Dino-lite</td>
			<td style="width:144px;">Dinocapture 2.0</td>
			<td style="width:144px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:144px;">Voltmeter</td>
			<td style="width:144px;">Amprobe</td>
			<td style="width:144px;">AM-510</td>
			<td style="width:144px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:144px;">Optical Cage System</td>
			<td style="width:144px;">Thorlabs</td>
			<td style="width:144px;"></td>
			<td style="width:144px;">30 mm cage system</td>
		</tr>
		<tr height="37">
			<td height="37" style="height:37px;width:144px;">Goniometers</td>
			<td style="width:144px;">Thorlabs</td>
			<td style="width:144px;">RP01 - &#216;2</td>
			<td style="width:144px;">Manual rotation stage</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:144px;">Diode lasers</td>
			<td style="width:144px;">Thorlabs</td>
			<td style="width:144px;"></td>
			<td style="width:144px;"></td>
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		<tr height="37">
			<td height="37" style="height:37px;width:144px;">Electrochemical cell</td>
			<td style="width:144px;">Adams &#38; Chittenden Scientific Glass</td>
			<td style="width:144px;">Custom-made product</td>
			<td style="width:144px;"></td>
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		<tr height="37">
			<td height="37" style="height:37px;width:144px;">Stainless steel capillary</td>
			<td style="width:144px;">Restek</td>
			<td style="width:144px;"></td>
			<td style="width:144px;">0.007 in. ID</td>
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		<tr height="37">
			<td height="37" style="height:37px;width:144px;">SHV Coax Cable</td>
			<td style="width:144px;">SRS</td>
			<td style="width:144px;">Custom-made product</td>
			<td style="width:144px;"></td>
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		<tr height="37">
			<td height="37" style="height:37px;width:144px;">Sodium Perchlorate</td>
			<td style="width:144px;">Sigma-Aldrich</td>
			<td style="width:144px;"></td>
			<td style="width:144px;">ACS reagent, &#8805;98.0%</td>
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		<tr height="21">
			<td height="21" style="height:21px;width:144px;">Argon</td>
			<td style="width:144px;">Airgas</td>
			<td style="width:144px;">AR UHP300</td>
			<td style="width:144px;">Ultra-high purity</td>
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			<td height="73" style="height:73px;width:144px;">LabVIEW</td>
			<td style="width:144px;">National Instruments</td>
			<td style="width:144px;"></td>
			<td style="width:144px;">Software used to generate in-house program used to collect data</td>
		</tr>
	</tbody>
</table>

total internal reflection absorption spectroscopy (tiras) for the detection of solvated electrons at a plasma-liquid interface

本文提出的全内反射吸收光谱法 (拉斯) 方法采用廉价的二极管激光器, 检测与水溶液接触的低温等离子体产生的溶剂电子。溶剂电子是一种强大的还原剂, 它被认为在气体等离子体或放电和导电液体之间的界面化学中起着重要的作用。然而, 由于在界面上的反应物种的高度局部浓度, 他们有一个短的平均寿命 (〜1µs), 这使得他们极其难以检测。拉斯技术使用独特的全内反射几何结合振幅调制锁定放大, 以区分溶剂电子的吸光度信号从其他杂散噪声源。这使得原位检测界面区域中的短寿命中间体, 而不是溶液中的稳定产品的批量测量。这种方法对于等离子体电化学领域尤其有吸引力, 因为在那里, 许多重要的化学物质都是由短寿命自由基驱动的。本实验方法用于分析亚硝酸盐的还原 (无2-(蒽醌)), 硝酸盐 (没有3-(蒽醌)), 过氧化氢 (H2O2 (蒽醌)) 和溶解的二氧化碳 (CO2 (蒽醌)) 通过等离子体溶剂电子, 并推断出有效速率常数。这种方法的局限性可能出现在非预期的平行反应中, 例如等离子体中的空气污染, 而减少的电化学产品的沉淀也会阻碍吸光度的测量。总的来说, 拉斯法可以成为研究等离子体-液体界面的有力工具, 但其有效性取决于所研究的特定系统和反应化学。

如步骤5所述, 本实验测量吸收信号的余弦和正弦分量、它们之间的相角和信号的大小。在图 4中显示了信号的大小及其两个分量的图。
有时, 将有可能不是最佳或甚至无法使用的测量。这可能是由于激光与等离子束的失调或引入噪声进入系统。一个好的和坏的测量的例子可以在图 5?...

Watch this Scientific Journal Video about Total Internal Reflection Absorption Spectroscopy TIRAS for the Detection of Solvated Electrons at a Plasma-liquid Interface at JoVE.com

Total Internal Reflection Absorption Spectroscopy TIRAS for the Detection of Solvated Electrons at a Plasma-liquid Interface

本文提出了一种全内反射吸收光谱法 (拉斯) 测量等离子体-液体界面的短活自由基。特别是, 拉斯是用来识别溶剂电子的基础上, 其光学吸收的红光近700纳米。

全内反射吸收光谱法 (拉斯) 在等离子体-液体界面上检测溶剂电子

The total internal reflection absorption spectroscopy (TIRAS) method presented in this article uses an inexpensive diode laser to detect solvated ...

total-internal-reflection-absorption-spectroscopy-tiras-for-detection

Research

JoVE Journal

Chemistry

Total Internal Reflection Absorption Spectroscopy (TIRAS) for the Detection of Solvated Electrons at a Plasma-liquid Interface

13.6K 次观看.  University of Notre Dame. 本文提出了一种全内反射吸收光谱法 (拉斯) 测量等离子体-液体界面的短活自由基。特别是, 拉斯是用来识别溶剂电子的基础上, 其光学吸收的红光近700纳米。

视频: Total Internal Reflection Absorption Spectroscopy TIRAS for the Detection of Solvated Electrons at a Plasma-liquid Interface

Isolation and Chemical Characterization of Lipid A from Gram-negative Bacteria

Lipopolysaccharide (LPS) is the major cell surface molecule of gram-negative bacteria, deposited on the outer leaflet of the outer membrane bilayer. LPS can be subdivided into three domains: the distal O-polysaccharide, a core oligosaccharide, and the lipid A domain consisting of a lipid A molecular species and 3-deoxy-D-manno-oct-2-ulosonic acid residues (Kdo). The lipid A domain is the only component essential for bacterial cell survival. Following its synthesis, lipid A is chemically modified in response to environmental stresses such as pH or temperature, to promote resistance to antibiotic compounds, and to evade recognition by mediators of the host innate immune response. The following protocol details the small- and large-scale isolation of lipid A from gram-negative bacteria. Isolated material is then chemically characterized by thin layer chromatography (TLC) or mass-spectrometry (MS). In addition to matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) MS, we also describe tandem MS protocols for analyzing lipid A molecular species using electrospray ionization (ESI) coupled to collision induced dissociation (CID) and newly employed ultraviolet photodissociation (UVPD) methods. Our MS protocols allow for unequivocal determination of chemical structure, paramount to characterization of lipid A molecules that contain unique or novel chemical modifications. We also describe the radioisotopic labeling, and subsequent isolation, of lipid A from bacterial cells for analysis by TLC. Relative to MS-based protocols, TLC provides a more economical and rapid characterization method, but cannot be used to unambiguously assign lipid A chemical structures without the use of standards of known chemical structure. Over the last two decades isolation and characterization of lipid A has led to numerous exciting discoveries that have improved our understanding of the physiology of gram-negative bacteria, mechanisms of antibiotic resistance, the human innate immune response, and have provided many new targets in the development of antibacterial compounds.

Isolation and characterization of the lipid A domain of lipopolysaccharide (LPS) from gram-negative bacteria provides insight into cell surface based mechanisms of antibiotic resistance, bacterial survival and fitness, and how chemically diverse lipid A molecular species differentially modulate host innate immune responses.

隔离和脂质A的化学表征革兰氏阴性菌

Lipopolysaccharide (LPS) is the major cell surface molecule of gram-negative bacteria, deposited on the outer leaflet of the outer membrane bilayer. LPS ...

科研

化学

Optimization of Synthetic Proteins: Identification of Interpositional Dependencies Indicating Structurally and/or Functionally Linked Residues

Protein alignments are commonly used to evaluate the similarity of protein residues, and the derived consensus sequence used for identifying functional units (e.g., domains). Traditional consensus-building models fail to account for interpositional dependencies &#8211; functionally required covariation of residues that tend to appear simultaneously throughout evolution and across the phylogentic tree. These relationships can reveal important clues about the processes of protein folding, thermostability, and the formation of functional sites, which in turn can be used to inform the engineering of synthetic proteins. Unfortunately, these relationships essentially form sub-motifs which cannot be predicted by simple &#8220;majority rule&#8221; or even HMM-based consensus models, and the result can be a biologically invalid &#8220;consensus&#8221; which is not only never seen in nature but is less viable than any extant protein. We have developed a visual analytics tool, StickWRLD, which creates an interactive 3D representation of a protein alignment and clearly displays covarying residues. The user has the ability to pan and zoom, as well as dynamically change the statistical threshold underlying the identification of covariants. StickWRLD has previously been successfully used to identify functionally-required covarying residues in proteins such as Adenylate Kinase and in DNA sequences such as endonuclease target sites.

Synthetic protein sequences based on consensus motifs typically ignore co-evolving residues, that imply interpositional dependencies (IPDs). IPDs can be essential to activity, and designs that disregard them may result in suboptimal results. This protocol uses StickWRLD to identify IPDs and help inform rational protein design, resulting in more efficient results.

优化合成蛋白质:Interpositional依赖性的鉴定指示在结构和/或功能性连接的残留

Protein alignments are commonly used to evaluate the similarity of protein residues, and the derived consensus sequence used for identifying functional ...

Protocol for the Synthesis of Ortho-trifluoromethoxylated Aniline Derivatives

Molecules bearing trifluoromethoxy (OCF3) group often show desired pharmacological and biological properties. However, facile synthesis of trifluoromethoxylated aromatic compounds remains a formidable challenge in organic synthesis. Conventional approaches often suffer from poor substrate scope, or require use of highly toxic, difficult-to-handle, and/or thermally labile reagents. Herein, we report a user-friendly protocol for the synthesis of methyl 4-acetamido-3-(trifluoromethoxy)benzoate using 1-trifluoromethyl-1,2-benziodoxol-3(1H)-one (Togni reagent II). Treating methyl 4-(N-hydroxyacetamido)benzoate (1a) with Togni reagent II in the presence of a catalytic amount of cesium carbonate (Cs2CO3) in chloroform at RT afforded methyl 4-(N-(trifluoromethoxy)acetamido)benzoate (2a). This intermediate was then converted to the final product methyl 4-acetamido-3-(trifluoromethoxy)benzoate (3a) in nitromethane at 120 &#176;C. This procedure is general and can be applied to the synthesis of a broad spectrum of ortho-trifluoromethoxylated aniline derivatives, which could serve as useful synthetic building blocks for the discovery and development of new pharmaceuticals, agrochemicals, and functional materials.

Protocol for the Synthesis of Ortho-trifluoromethoxylated Aniline Derivatives

An operationally simple procedure for the synthesis of ortho-trifluoromethoxylated aniline derivatives via a two-step sequence of O-trifluoromethylation of N-aryl-N-hydroxyacetamide followed by thermally induced intramolecular OCF3-migration is reported.

协议的合成<em&gt;邻</em&gt; -trifluoromethoxylated苯胺类化合物

Molecules bearing trifluoromethoxy (OCF3) group often show desired pharmacological and biological properties. However, facile synthesis of ...

1,3,5-Triphenylbenzene and Corannulene as Electron Receptors for Lithium Solvated Electron Solutions

The authors report on conductivity studies carried out on lithium solvated electron solutions (LiSES) prepared using two types of polyaromatic hydrocarbons (PAH), namely 1,3,5-triphenylbenzene and corannulene, as electron receptors. The solid PAHs were first dissolved in tetrahydrofuran (THF) to form a solution. Metallic lithium was then dissolved into these PAH/THF solutions to yield either blue or greenish blue solutions, colors which are indicative of the presence of solvated electrons. Conductivity measurements at ambient temperature carried out on 1,3,5-triphenylbenzene-based LiSES, denoted by LixTPB(THF)24.7 (x = 1, 2, 3, 4), showed an increase of conductivity with increase of Li:PAH ratio from x = 1 to 2. However, the conductivity gradually decreased upon further increasing the ratio. Indeed the conductivity of LixTPB(THF)24.7 for x = 4 is even lower than for x = 1. Such behavior is similar to that of the previously reported LiSES prepared from biphenyl and naphthalene. Conductivity versus temperature measurements on corannulene-based LiSES, denoted by LixCor(THF)247 (x = 1, 2, 3, 4, 5), showed linear relationships with negative slopes, indicating a metallic behavior similar to biphenyl and naphthalene-based LiSES.

The authors report on conductivity studies carried out on lithium solvated electron solutions (LiSES) prepared using 1,3,5-triphenylbenzene (TPB) and corannulene as electron receptors.

1,3,5-三苯和碗烯作为电子受体锂溶剂化电子解决方案

The authors report on conductivity studies carried out on lithium solvated electron solutions (LiSES) prepared using two types of polyaromatic ...

Insights into the Interactions of Amino Acids and Peptides with Inorganic Materials Using Single-Molecule Force Spectroscopy

The interactions between proteins or peptides and inorganic materials lead to several interesting processes. For example, combining proteins with minerals leads to the formation of composite materials with unique properties. In addition, the undesirable process of biofouling is initiated by the adsorption of biomolecules, mainly proteins, on surfaces. This organic layer is an adhesion layer for bacteria and allows them to interact with the surface. Understanding the fundamental forces that govern the interactions at the organic-inorganic interface is therefore important for many areas of research and could lead to the design of new materials for optical, mechanical and biomedical applications. This paper demonstrates a single-molecule force spectroscopy technique that utilizes an AFM to measure the adhesion force between either peptides or amino acids and well-defined inorganic surfaces. This technique involves a protocol for attaching the biomolecule to the AFM tip through a covalent flexible linker and single-molecule force spectroscopy measurements by atomic force microscope. In addition, an analysis of these measurements is included.

Here we present a protocol to measure the force of interactions between a well-defined inorganic surface and either peptides or amino acids by single-molecule force spectroscopy measurements using an atomic force microscope (AFM). The information obtained from the measurement is important to better understand the peptide-inorganic material interphase.

洞察氨基酸和多肽与无机材料的使用相互作用的单分子力谱

The interactions between proteins or peptides and inorganic materials lead to several interesting processes. For example, combining proteins with minerals ...

NMR Spectroscopy as a Robust Tool for the Rapid Evaluation of the Lipid Profile of Fish Oil Supplements

The western diet is poor in n-3 fatty acids, therefore the consumption of fish oil supplements is recommended to increase the intake of these essential nutrients. The objective of this work is to demonstrate the qualitative and quantitative analysis of encapsulated fish oil supplements using high-resolution 1H and 13C NMR spectroscopy utilizing two different NMR instruments; a 500 MHz and an 850 MHz instrument. Both proton (1H) and carbon (13C) NMR spectra can be used for the quantitative determination of the major constituents of fish oil supplements. Quantification of the lipids in fish oil supplements is achieved through integration of the appropriate NMR signals in the relevant 1D spectra. Results obtained by 1H and 13C NMR are in good agreement with each other, despite the difference in resolution and sensitivity between the two nuclei and the two instruments. 1H NMR offers a more rapid analysis compared to 13C NMR, as the spectrum can be recorded in less than 1 min, in contrast to 13C NMR analysis, which lasts from 10 min to one hour. The 13C NMR spectrum, however, is much more informative. It can provide quantitative data for a greater number of individual fatty acids and can be used for determining the positional distribution of fatty acids on the glycerol backbone. Both nuclei can provide quantitative information in just one experiment without the need of purification or separation steps. The strength of the magnetic field mostly affects the 1H NMR spectra due to its lower resolution with respect to 13C NMR, however, even lower cost NMR instruments can be efficiently applied as a standard method by the food industry and quality control laboratories.

Here, high-resolution 1H and 13C Nuclear Magnetic Resonance (NMR) spectroscopy was used as a rapid and reliable tool for quantitative and qualitative analysis of encapsulated fish oil supplements.

核磁共振作为鱼油补充剂的血脂的快速评价一个强大的工具

The western diet is poor in n-3 fatty acids, therefore the consumption of fish oil supplements is recommended to increase the intake of these essential ...

Electrochemical Impedance Spectroscopy as a Tool for Electrochemical Rate Constant Estimation

Electrochemical impedance spectroscopy (EIS) was used for advanced characterization of organic electroactive compounds along with cyclic voltammetry (CV). In the case of fast reversible electrochemical processes, current is predominantly affected by the rate of diffusion, which is the slowest and limiting stage. EIS is a powerful technique that allows separate analysis of stages of charge transfer that have different AC frequency response. The capability of the method was used to extract the value of charge transfer resistance, which characterizes the rate of charge exchange on the electrode-solution interface. The application of this technique is broad, from biochemistry up to organic electronics. In this work, we are presenting the method of analysis of organic compounds for optoelectronic applications.

Electrochemical impedance spectroscopy (EIS) of species that undergo reversible oxidation or reduction in solution was used for determination of rate constants of oxidation or reduction.

电化学阻抗谱作为电化学速率常数估计的一种工具

Electrochemical impedance spectroscopy (EIS) was used for advanced characterization of organic electroactive compounds along with cyclic voltammetry (CV). ...

Detection and Quantification of Plasmodium falciparum in Aqueous Red Blood Cells by Attenuated Total Reflection Infrared Spectroscopy and Multivariate Data Analysis

We demonstrate a method of quantification and detection of parasites in aqueous red blood cells (RBCs) by using a simple benchtop Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) spectrometer in conjunction with Multivariate Data Analysis (MVDA). 3D7 P. falciparum were cultured to 10% parasitemia ring stage parasites and used to spike fresh donor isolated RBCs to create a dilution series between 0&#8211;1%. 10 &#181;L of each sample were placed onto the center of the ATR diamond window to acquire the spectrum. The sample data was treated to improve the signal to noise ratio and to remove the contribution of water, and then the second derivative was applied to resolve spectral features. The data were then analyzed using two types of MVDA: first Principal Component Analysis (PCA) to determine any outliers and then Partial Least Squares Regression (PLS-R) to build the quantification model.

Detection and Quantification of Plasmodium falciparum in Aqueous Red Blood Cells by Attenuated Total Reflection Infrared Spectroscopy and Multivariate Data Analysis

Here, we present a protocol for the detection and quantification of Plasmodium falciparum in infected aqueous red blood cells using an attenuated total reflection infrared spectrometer and multivariate data analysis.

衰减全反射红外光谱和多变量数据分析检测和定量水红血球中恶性疟原虫

We demonstrate a method of quantification and detection of parasites in aqueous red blood cells (RBCs) by using a simple benchtop Attenuated Total ...

Elemental-sensitive Detection of the Chemistry in Batteries through Soft X-ray Absorption Spectroscopy and Resonant Inelastic X-ray Scattering

Energy storage has become more and more a limiting factor of today's sustainable energy applications, including electric vehicles and green electric grid based on volatile solar and wind sources. The pressing demand of developing high-performance electrochemical energy storage solutions, i.e., batteries, relies on both fundamental understanding and practical developments from both the academy and industry. The formidable challenge of developing successful battery technology stems from the different requirements for different energy-storage applications. Energy density, power, stability, safety, and cost parameters all have to be balanced in batteries to meet the requirements of different applications. Therefore, multiple battery technologies based on different materials and mechanisms need to be developed and optimized. Incisive tools that could directly probe the chemical reactions in various battery materials are becoming critical to advance the field beyond its conventional trial-and-error approach. Here, we present detailed protocols for soft X-ray absorption spectroscopy (sXAS), soft X-ray emission spectroscopy (sXES), and resonant inelastic X-ray scattering (RIXS) experiments, which are inherently elemental-sensitive probes of the transition-metal 3d and anion 2p states in battery compounds. We provide the details on the experimental techniques and demonstrations revealing the key chemical states in battery materials through these soft X-ray spectroscopy techniques.

Here, we present a protocol for typical experiments of soft X-ray absorption spectroscopy (sXAS) and resonant inelastic X-ray scattering (RIXS) with applications in battery material studies.

软 x 射线吸收光谱和共振非弹性 x 射线散射法检测电池化学成分的元素敏感度

Energy storage has become more and more a limiting factor of today's sustainable energy applications, including electric vehicles and green electric grid ...

Imaging Corrosion at the Metal-Paint Interface Using Time-of-Flight Secondary Ion Mass Spectrometry

Corrosion developed at the paint and aluminum (Al) metal-paint interface of an aluminum alloy is analyzed using time-of-flight secondary ion mass spectrometry (ToF-SIMS), illustrating that SIMS is a suitable technique to study the chemical distribution at a metal-paint interface. The painted Al alloy coupons are immersed in a salt solution or exposed to air only. SIMS provides chemical mapping and 2D molecular imaging of the interface, allowing direct visualization of the morphology of the corrosion products formed at the metal-paint interface and mapping of the chemical after corrosion occurs. The experimental procedure of this method is presented to provide technical details to facilitate similar research and highlight pitfalls that may be encountered during such experiments.

Time-of-flight secondary ion mass spectrometry is applied to demonstrate the chemical mapping and corrosion morphology at the metal-paint interface of an aluminum alloy after being exposed to a salt solution compared with a specimen exposed to air.

全内反射吸收光谱法 (拉斯) 在等离子体-液体界面上检测溶剂电子

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