我们感谢罗伯特 · 伯杰 （菲利普斯大学马尔堡，德国） 一般激励讨论我们的数据和分子手性的解释。我们对于感谢茱莉亚凯德罗夫斯基、 亚历山大 Schießer 和 Michael Reggelin 从土达姆施塔特 （德国），以及本杰明 Spenger、 曼纽尔 · 马泽瑙尔 Jürgen Stohner 从 ZHAW Wädenswil （瑞士） 提供样品。
Hessen 国家倡议科学和卓越的经济成长，焦点 ELCH （电子系统动力学的手性） 和联邦教育部及研究 (BMBF) 下支持该项目。MS 由阿道夫 · 梅塞尔基金会承认金融支持。

注意: 请务必要熟悉所有可能危害连接与实验和实验室。下面的过程包括第四类激光器、 高电压和真空。物种要追究咨询材料安全数据表 (MSDS)。
 1。 制备 <ol><li>筹备考虑 注: 实际的实验开始前，两个主要选择必须作出; 第一次在调查可能的物种和第二在光谱仪电场。这里假定安装了以前使用其他实验和光谱仪本身不会因此而重新塑造。
	<ol><li><ol><li>样品的选择可望碎裂的示例进行签名的惯用手或结构特征进行调查。请牢记，氢原子常常被释放作为中性碎片;可能不能区分只是氢原子的数量不同的官能团。开始与简单 （也许非手性） 的物种，如应用或 haloethanes.</li>
			<li>检查样品，至少 0.02 mol 是可用的因为这是用在实验中获得成功的最小数额为止</li>
			<li>验证足够的蒸汽压力是可以实现的示例。根据该装置的设计，蒸汽压 &#62; 5 自置居所津贴是足够的射流密度激光实验的必要条件。如果蒸气压是明显降低，检查如果可以通过加热样品达到所需的蒸汽压力。这可能为液体和固体样品，由于后者的升华。如果加热是必需的它是需要有积极的温度梯度，沿路径的气体输送系统 （与喷嘴的最热门的组成部分） 为了避免凝结。更先进的样品制备计划像可能考虑由承运人气回升。</li>
		</ol></li> <li>光谱仪中的电场强度的选择 注: 50 到 100 V/cm 值被证明合理的库仑爆炸影像。最佳值，然而，取决于分光计的几何形状。以下步骤显示如何优化的电场强度。
		<ol><li>估计预期的阳离子碎片的飞行时间。如果光谱仪仅包含与长度 s 和电场强度 E 的均匀场区域，颗粒的质量 m 和电荷 q 的飞行平均时间只是给出 < img alt ="方程 1"src ="/files/ftp_upload/56062/56062eq1.jpg"/ ></li> <li>利用飞行时间 t 以上计算和公式估计传播 x 的片段阳离子与质量为 m 的探测器 < img alt ="方程 2"src ="/files/ftp_upload/56062/56062eq2.jpg"/ > 离子将获得动量 p x 的势头 （质子到 150 的原子单位） 达 400 原子单位。</li>
			<li>如果轻离子物种空间传播 x 大于探测器半径，增加电场强度计算中的，直到蔓延是几毫米比探测器尺寸小得多。电场强度不应该因为这会导致较低的分辨率为重碎片散布出来少在探测器上的高很多。</li>
		</ol></li></ol></li> <li>的实验装置检查 注: 实际测量之前，它已经要检查实验装置有充分的准备。
	<ol><li>互动室真空度的检查 &#60; 1 × 10 -9 自置居所津贴。如果这不是个案，残余气体将导致高背景率。如有疑问关于真空的条件，继续直到步骤 2.2.1 其残余气体的电离率确定。如果压力太高，执行泄漏检查。如果没有泄漏是明显的放入烤箱，分庭几天。</li>
		<li>验证的连接电源电压和探测器信号根据手册或实验描述。</li>
		<li>检查测量计算机上的数据采集软件是能够记录和分析至少四个离子。请确保死区时间的电子模块和信号的脉冲宽度小于 30 ns。</li>
	</ol></li> <li>准备样品交货 <ol><li>验证样品交货管是清洁和连接收紧。如果样品是腐蚀 （例如 酸性） 确保交付系统和粗加工泵的真空室中的所有组件都是调查对象的选取与兼容。粗加工的泵泵样本交付系统，打开阀门和验证实验的腔内的压力不会增加。</li>
		<li>清洁和准备样品收件人。用丙酮或通常实验室玻璃器皿清洗机超声波浴是充足的。</li>
		<li>编写储层和样品交货系统的加热如果样品需要加热 （参看 1.1.1.3）。最方便的方式是使用可调加热电路，加热丝、 温度传感器和温度控制器组成的每一个。</li>
		<li>如果样品具有很低的蒸汽压，或者如果它趋于形式集群 （例如 酸），接机或 copropagation 与惰性气体使用不同的方法。修改的设计，根据这些要求的气行。</li>
		<li>检查分子射流相一致。为此目的，使用稀有气体样品 （如 氩气） 从而达到密集射流 （大约 1 酒吧绝对压力应该足够为 50 微米的喷嘴）。通过移动的机械手的喷嘴安装最大化在射流转储部分压力。</li>
	</ol></li> <li>提供飞秒激光脉冲 注: 电离脉冲系统提供的飞秒激光。描述这种激光和其详细的使用已经超出本议定书的范围。如果使用了一种商业激光系统，请参考手册。
	<ol><li>上的激光开关并检查激光束的输出配置文件。</li>
		<li>检查和纠正 （如果必要） 通过调整各自的镜子实验的入口窗口的光束路径。</li>
		<li>如果有必要，用各自的机械手对齐试验室内的聚焦镜。中心对入射光束的聚焦镜反射。</li>
		<li>插入过滤器或旋转偏光器梁路径中的，以达到大约 6 x 10 14 W/厘米 2 峰值强度。对于正常库仑爆炸成像，使用线性极化。如果要追究二向色性的影响，通过四分之一波片，只是之前入口窗口更改偏振。</li>
		<li>在一个地方，它可以在其中记录的激光脉冲 （例如 一反射或传输通过对准镜） 的可靠副本插入一个光电二极管。光电二极管的输出连接到一台示波器和验证二极管产生清洁激光重复频率脉冲。</li>
		<li>总是阻止在不使用时梁。</li>
	</ol></li></ol> 2。拐弯处光谱仪和探测器 注: 议定书 》 的这一部分略取决于光谱仪和探测器系统的实际实现。描述在这里是有效的标准的 COLTRIMS 设置与六角延迟线探测器 (HEX75)。 10 在此实现中，探测器具有 7 输出通道: 一个用于微通道板(MCPs)，两个用于每个三层的阳极。
<ol><li>电源打开。
	<ol><li>关掉在互动室真空计，因为他们可能会产生离子探测器被视为。</li>
		<li>连接被放大的信号输出 (使用一种快速的放大器放大 &#8776; 100) 的快速 （最好是） 通用示波器对 MCP。将示波器设置为每个部分在时间尺度上的 5 或 10 ns 和 100 mV 每司在信号范围内。验证电子噪声小于 30 mV。</li>
		对高电压 <li>开关电源检测器。典型的离子化检测器，电压为-2,000 V 的前面板和 300 V 为阳极侧。电压取决于年龄的枇杷和应设置这样的模拟信号是最大，但不是饱和。检查当前。它取决于在探测器枇杷的抵抗，但不是应超过 50 µ A。在示波器的踪影，几个信号每秒几个几百毫伏信号高度应可见 (&#39; 暗计数 &#39;)。</li>
		<li>调到价值建立在步 1.1.2 光谱仪的电力供应。</li>
	</ol></li> <li>检查通过的残余气体电离探测器信号 注: 探测器启动的详细的说明，也可以见于各自手册。 11 ， 12 <ol><li>衰减激光强度对估计值低于 10 14 W/厘米 2 的重点。解除阻止激光和观看示波器跟踪。如果这导致率超过 5%的激光重复频率，在会议厅的残余气体量太高或激光束触动光谱仪。在继续之前解决此问题。如果计数率显著低于激光重复频率的 5%，逐步增加激光强度。</li>
		<li>有仔细看看信号。他们应该只显示一个峰几个几百个 mV 和 no &#39; 响 &#39; （后实际脉冲振荡）。MCP 信号的宽度应不超过 10 ns (FWHM)。</li>
		<li>看看所有六个阳极信号示波器记录。信号是更广泛这里 (20-30 ns)，和通常在电压要低一些。再次检查无干扰信号存在。如果所有的阳极信号低于 100 mV，增加电压 （步骤 2.1.3） 的步骤，50 诉调谐放大器的增益能够得到相同的脉冲高度为所有通道。</li>
		<li>通过恒比鉴频器 (CFD) 将这些模拟信号转换为标准的-0.8 V 的尼姆信号 （核仪表模块）。检查每个实验运行前 CFD 的设置。详细的说明，请参阅手册在因特网上。 12 送入尼姆脉冲时间数字转换器 (TDC)，用于记录与高分辨率 (通常 25 ps) 脉冲的到达时间。这些时间信号的数据采集和分析软件的输入。</li>
		<li>打开数据采集软件和数据记录的开始。看起来在每个通道-命中分布直方图应该是类似所有通道。如果那不是这样的一些渠道，检查这些渠道的 CFD 设置 （步骤 2.2.4）。检查通过另外检查信号总和设置运行时间每个探测器层探测器手册中所述。如有必要，更正的差价合约设置。</li>
		<li>显示探测器图像中的数据采集软件。探测器应显示为带有弥漫现场 （激光焦点图像） 在中心的圆圈。点的扩展主要是获取电离的残余气体的热速度。</li>
		<li>将信号馈入的激光二极管 （步骤 1.5.5） 的数据采集、 最好是探测器信号的方式相同。在软件中显示飞行时间谱。通过计算其预期的时间-的-航班从光谱仪几何 （步骤 1.1.2.1） 相关观测的峰残余气体种类 （H 2、 H 2 O，可能 N 2、 O 2、 CO 2）。</li>
		<li>试图通过计数率，使用激光系统的色散修正最大化最小化的激光脉冲持续时间。短脉冲 （和更高的峰值强度） 将导致率显著上升。</li>
		<li>如果背景压力是如此之低，收费不是足够高，以执行上述步骤，打开燃气射流 （见步骤 2.3），然后执行步骤 2.2.1 直到 2.2.8。飞行时间谱的步 2.2.7 然后显然非主导的射流中物种。</li>
		<li>发现了探测器的绝对方向。为了做到这一点，移动聚焦镜，使激光焦点图像移明显在探测器图像软件中。请注意 （用于步 5.1.1） 移动的方向。此步骤很重要测量的绝对构型的因为它能够避免测量动量的真实实验室空间反演.</li>
	</ol></li> <li>发现的气体射流和激光重叠。
	<ol><li>打开气体射流 1.3.5 步骤中所述。</li>
		<li>如果率增加和一个非常狭窄的地方 (&#39; 射流现货 &#39;) 可见探测器图像数据采集程序，在确保分子喷墨和激光束重叠的至少部分。在这种情况下，调整机械手的聚焦镜仔细地最大限度地在射流点计数。在最优重叠，他们应超过数从残余气体 （步骤 2.2） 的数量级。它可能需要减少激光强度，因为 MCP 计数率不应超过 30 千赫。如果由于残余气体电离背景太高比的信号从气体射流，考虑扩展激光束来达到一个更窄的重点在会议厅外。</li>
		<li>如果没有喷点在探测器图像上可见，调整机械手的聚焦镜在大步骤查找重叠在一起，并继续然后步 2.3.2。</li>
	</ol></li></ol> 3。样品交期 <ol><li>准备好所有的工具、 收件人垫圈和其他必需品，如样品暴露于环境应该最小化。</li>
	<li>填充到收件人将连接到实验的样本。如果样品具有很高的蒸气压力，冷却收件人和事先来样来减少蒸发损失，在这一步。</li>
	<li>将样品缸连接到喷射系统，并拧紧连接真空证明。冷却钢瓶 （以避免样品损失） 和几秒钟，以排除空气泵。</li>
	<li>阀门开启到喷嘴。在源湛压力误码率应增加到至少几个 10 -5 hPa。</li>
	<li>验证喷射点是可见的 （步骤 2.3.2） 和识别中飞行时间谱的最突出峰。</li>
	<li>优化实验条件 (调整温度、 激光强度的所涉及气体压力 &#8230;)，最大限度地从样品的电离速率。请记住，加热，导致组件的热膨胀系数，喷射机械手 （步骤 1.4.5） 调整可能是必要。</li>
</ol> 4。测量 注: 数据采集软件中执行以下步骤。
<ol><li>检查质谱和巧合谱。
	<ol><li>飞行时间频谱图并将不同的山峰分配给群众，可以发生在碎片 （父大规模、 丰富的片段）。</li>
		<li>绘制在 x 轴上的第一个离子的飞行时间和 y 轴上的第二个离子的飞行时间。以多项罪名的区域指示在巧合中发出的两个片段。锋利的对角线表明分手成两个带电碎片。</li>
		<li>情节类似的直方图的更多的粒子，例如 总和的航班时间为 x 轴上的第一次两个离子和为 y 轴上的第三和第四次离子飞行时间的总和。示例这种 multicoincidence 的频谱如 图 2 所示。</li>
		<li>尝试识别四粒子或五粒子谱不同的分手并检查是否有可能产下调查的结构信息的分手。</li>
	</ol></li> <li>估计测量时间。
	<ol><li>让实验运行约 1 小时，并检查计数为所选的通道数目。小心不要把背景事件。</li>
		<li>乘以这个数目与实验的预期时间。总人数中的相关渠道的计数应该至少几千。</li>
		<li>如果在所选的通道计数数目远远低于这个数字，增加激光强度并重复步骤 4.2.1 和 4.2.2。要小心的是仍然足够低，重合检测率 （见导言）。</li>
	</ol></li></ol> 5。数据分析 注: 库仑爆炸成像实验的数据分析是一种复杂但奖励任务因为很多参数可以微调后实验和大量的实测值的相关性可以探索动量。实验数据分析软件中后通常执行所有以下步骤。
<ol><li>校准实验参数 注: 在第一步，确保重建从探测器的位置和时间信息是正确的。类似于调整电子 （步骤 2.2） 的确切过程取决于特定的实现，在这种情况下数据分析软件。因此，可以考虑只一些一般性的建议。
	<ol><li>情节图像的探测器。检查所有三个阳极层，探测器图像的大小对应于 MCP 的实际大小和探测器图像的中心在 0。验证所有的三层组合产量相同的探测器图像。如果必要的旋转或翻转的检测器，这样的实验室帧对应探测器图像的坐标系统 （使用的测量步骤 2.2.10）。</li>
		<li>确定不同群众在飞行时间谱和适合分光计功能 （步骤 1.1.2.1） 为这些值。在此步骤中的重要参数是飞行时间偏移量 t 0，所有飞行时间值都必须更正的干</li>
		<li>看一看 （参见步骤 4.1.4） 的巧合谱和识别有前途分手渠道。建议一门放几个 100 的飞行时间值 ns 周围的有趣模式和只选择这些为进一步采取的步骤的窗口内的事件。否则为不必要的事件的量太大，会慢下来分析。</li>
		<li>存储 x、 y、 t 为进一步分析的修正的值。</li>
	</ol></li> <li>计算离子动量和能量。
	<ol><li>使用的实验参数和假设的大众收费比率，计算的动力组件 p x，p y 和 p z。使用这些计算动能的片段和他们的总和，动能释放 (KER)。</li>
		<li>使用巧合谱 （步骤 4.1.4） 用于微调电场强度 E 和光谱仪长度 s 和情节与飞行时间影响位置来确定 的位置偏移量 x 0 和 y 0 和速度 v j et 气体射流。如果精度标定是必要的使用 N 2 和分裂成两个单独的 O 2 控物种非常狭窄，好特征振动级数在动能释放 （见参考文献 13 和引用其中）。
		<ol><li>绘制 p x vs p y 等，并调整参数，以便动量分布在动量空间 （例如，关于在二维图形中的圆圈） 的球面上，以 0 为中心。这是，动能不应依赖离子片段的发射方向。</li>
			<li>绘制所有碎片从分子分手总和的势头。对于完整的分手，分布应窄 (通常 &#60; 10 原子单元动量) 和中心在 0.</li>
		</ol></li></ol></li> <li>选择相关的事件和探讨分子体系的性质。
	<ol><li>从背景分离实际的分手事件，通过设置约束在周围观察峰 （通常少于 20 原子单位在每个方向） 的总和势头。</li>
		<li>对于这些事件，使用矢量算法来构造包含结构信息，以进行调查的数量。下面一节中给出了实例为左和右旋异构体之间的区别。</li>
	</ol>
	</li>
</ol>

<ol>
	<li>G&#252;bitz, G., Schmid, M. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chiral+Separation+by+Chromatographic+and+Electromigration+Techniques.+A+Review.">Chiral Separation by Chromatographic and Electromigration Techniques. A Review.</a> Biopharm. Drug Disposition. 22, 291-336 (2001).</li><li>Berova, N., Polaravapu, P. L., Nakanishi, K., Woody, R. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Comprehensive Chiroptical Spectroscopy. , (2012).</li><li>Bijvoet, J. M., Peerdeman, A. F., van Bommel, A. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Determination+of+the+Absolute+Configuration+of+Optically+Active+Compounds+by+means+of+X-rays.">Determination of the Absolute Configuration of Optically Active Compounds by means of X-rays.</a> Nature. 168 (4268), 271-272 (1951).</li><li>Pitzer, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Direct+Determination+of+Absolute+Molecular+Stereochemistry+in+Gas+Phase+by+Coulomb+Explosion+Imaging.">Direct Determination of Absolute Molecular Stereochemistry in Gas Phase by Coulomb Explosion Imaging.</a> Science. 341 (6150), 1096-1100 (2013).</li><li>Pitzer, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Absolute+Configuration+from+Different+Multifragmentation+Pathways+in+Light-Induced+Coulomb+Explosion+Imaging.">Absolute Configuration from Different Multifragmentation Pathways in Light-Induced Coulomb Explosion Imaging.</a> Chem Phys Chem. 17 (16), 2465-2472 (2016).</li><li>Vager, Z., Naaman, R., Kanter, E. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Coulomb+Explosion+Imaging+of+small+molecules.">Coulomb Explosion Imaging of small molecules.</a> Science. 244 (4903), 426-431 (1989).</li><li>Herwig, P. H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Imaging+the+Absolute+Configuration+of+a+Chiral+Epoxide+in+the+Gas+Phase.">Imaging the Absolute Configuration of a Chiral Epoxide in the Gas Phase.</a> Science. 342 (6162), 1084-1186 (2013).</li><li>D&#246;rner, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cold+Target+Recoil+Ion+Momentum+Spectroscopy:+a+'momentum+microscope'+to+view+atomic+collision+dynamics.">Cold Target Recoil Ion Momentum Spectroscopy: a 'momentum microscope' to view atomic collision dynamics.</a> Physics Reports. 330, 95-192 (2000).</li><li>Ullrich, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Recoil-ion+and+electron+momentum+spectroscopy:+reaction-microscopes.">Recoil-ion and electron momentum spectroscopy: reaction-microscopes.</a> Rep. Prog. Phys. 66 (9), 1463-1545 (2003).</li><li>Jagutzki, O., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Multiple+Hit+Readout+of+a+Microchannel+Plate+Detector+With+a+Three-Layer+Delay-Line+Anode.">Multiple Hit Readout of a Microchannel Plate Detector With a Three-Layer Delay-Line Anode.</a> IEEE Trans Nucl Sci. 49 (5), 2477-2483 (2002).</li><li>. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> RoentDek GmbH MCP Delay Line Detector Manual. , (2017).</li><li>. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> RoentDek GmbH The RoentDek Constant Fraction Discriminators CFD8c, CFD7x, CFD4c, CFD1c and CFD1x. , (2017).</li><li>Zeller, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Imaging+the+He2+quantum+halo+state+using+a+free+electron+laser.">Imaging the He2 quantum halo state using a free electron laser.</a> PNAS. 113 (51), 14651-14655 (2016).</li><li>Pitzer, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stereochemical+configuration+and+selective+excitation+of+the+chiral+molecule+halothane.">Stereochemical configuration and selective excitation of the chiral molecule halothane.</a> J. Phys. B.: At. Mol. Opt. Phys. 49 (23), 234001 (2016).</li><li>Hine, J., Dowell, A. M., Singley, J. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Carbon+Dihalides+as+Intermediates+in+the+Basic+Hydrolysis+of+Haloforms:+IV+Relative+Reactivities+of+Haloforms.">Carbon Dihalides as Intermediates in the Basic Hydrolysis of Haloforms: IV Relative Reactivities of Haloforms.</a> J. Am. Soc. Chem. 78, 479-482 (1956).</li><li>Wales, B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+coincidence+detection+algorithm+for+improving+detection+rates+in+coulomb+explosion+imaging.">A coincidence detection algorithm for improving detection rates in coulomb explosion imaging.</a> Nucl. Instr. Meth. in Phys. Res. A. 667, 11-15 (2012).</li><li>Kastirke, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Konstruktion und Aufbau einer UHV-tauglichen COLTRIMS-Kammer. , (2014).</li><li>Calegari, F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Charge+migration+induced+by+attosecond+pulses+in+bio-relevant+molecules.">Charge migration induced by attosecond pulses in bio-relevant molecules.</a> J. Phys. B.: At. Mol. Opt. Phys. 49 (14), 142001 (2016).</li><li>Gaie-Levrel, F., Garcia, G. A., Schwell, M., Nahon, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=VUV+state-selected+photoionization+of+thermally-desorbed+biomolecules+by+coupling+an+aerosol+source+to+an+imaging+photoelectron/photoion+coincidence+spectrometer:+case+of+the+amino+acids+tryptophan+and+phenylalanine.">VUV state-selected photoionization of thermally-desorbed biomolecules by coupling an aerosol source to an imaging photoelectron/photoion coincidence spectrometer: case of the amino acids tryptophan and phenylalanine.</a> Phys. Chem. Chem. Phys. 13, 7024-7036 (2010).</li><li>Ablikim, U., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Identification+of+absolute+geometries+of+cis+and+trans+molecular+isomers+by+Coulomb+Explosion+Imaging.">Identification of absolute geometries of cis and trans molecular isomers by Coulomb Explosion Imaging.</a> Sci. Rep. 6, 38202 (2016).</li></ol>

作者宣称没有相互竞争的利益。

由于各种元器件，COLTRIMS 安装程序需要相当高水平的技术专长，尤其是在真空技术、 粒子检测、 快速的电子和数据分析等领域。在谈到复杂种类调查之前, 它应因此彻底检查如果运行安装程序的方法正确，例如通过执行和分析测量对双原子或原子的物种。
优化的强度和持续时间的激光脉冲与分子射流重叠实现尽可能多尽可能多个电离事件至关重要。随着动量分布可能?...

手性是性质的我们一直令人着迷的研究人员超过 150 年特征。在 19th世纪、 巴斯德、 范特霍夫和别人发现分子可以发生在并不是超级不再依赖-像我们的左手和右手的两个镜像结构。此属性被称为 '手'，从 '手' 的希腊语。
到目前为止，已发现了在热力学性质或左和右旋形式 （两个对映体'） 的能量水平无差异。分析了样品的惯用手，分离对映体，可以使用与其他手性分子相互作用，例如这样做的各种色谱方法。1 （振动） 圆二色性、 (V) CD、 旋光色散，ORD，Chiroptical 方法经常被雇用来区分对映体。2
微观结构测定的时候，这些技术需要附加信息，例如从量子化学计算。唯一的技术正在被广泛接受，直接确定的绝对构型是反常的 x 射线衍射。3
它最近被证明绝对构型的简单手性物种可以由库仑爆炸成像。4,5在这种方法，在气相中的分子是乘以电离，其余内核强烈排斥对方。这斥力导致的分子的快速瓦解 （' 爆炸'）。片段动量相关结构的分子 — — 小分子的大小和方向的动量方向对应出奇好债券轴。使用分子离子束从加速器，开创了分子结构测定的库仑爆炸。6这束箔技术最近也被应用于手性识别。7
与异常的 x 射线衍射、 样品不能结晶，但在气相中提供。这使得库仑爆炸方法挥发性化合物的理想和对 x-射线衍射从而补充。在某些情况下，甚至可以为单个分子已确定惯用手。
在实践中，分子的结构的精确重建已证明困难甚至甲烷衍生物，如中央碳与不同取代基的分子。这被归功于片段之间的相互作用不完全是库仑和并不是所有债券同时都打破。为了获得立体化学信息，尤其是以区分对映体，这种重建是幸运的是不必要的。相反，可以相关不同片段的动量向量，是明显的左和右旋分子的产量。为了得到可靠的结果，至少四个片段动量必须被记录下来。
为了衡量这势头信息，从一个 — — 且只有一个 — — 分子分手片段必须在一个单一的测量步骤中检测到。这种情况通常被称为 '重合检测'。此外，发射方向必须加以分析，这数额在实践中记录的时间和片段的位置影响在列表模式数据格式。
在原子和分子物理学中，技术已经采用静电光谱仪的大规模分离和时间和位置灵敏多命中探测器实现这种测量的方法。最突出的例子是 COLTRIMS （冷目标反冲离子动量谱仪） 设置 — — 也称为反应显微镜。8,9这种实验示意图图 1中给出。相反可以记录以及电子的标准 COLTRIMS，库仑爆炸成像要求只有离子化检测器。
光谱仪和探测器安装在超高真空条件下 (&#60; 1 × 10-9自置居所津贴) 以避免创建从残余气体离子。通过超音速规模扩张所造成的气态自由分子射流提供样品的单分子: 根据蒸汽压力，分子扩大通过小的喷嘴 （大约 50 µ m 直径） 放入真空。实验中，源分庭，这一部分被隔开相互作用区域通常两撇和差异泵浦的阶段。额外的差异抽水部分位于后面的互动区域转储气体射流，从而避免背景气体相互作用区域。
电离辐射与分子射流 90 ° 之下相交。大多数实验室现在用飞秒激光脉冲的同步辐射，快离子或电子冲击虽可能 '弹' 诱使库仑爆炸。
以下协议使重合的离子和飞秒激光成像的运行安装程序可在实验室中的假设。进四个或甚至五个片段诱导库仑爆炸所需的峰值强度必须大约 6 x 1014 W/厘米2。为了避免极长的测量，激光重复频率应 10 千赫或更多。这是关键的因为一方面，重合检测可以只确定如果碎片在激光焦点的概率远远低于 1 每激光脉冲 （理想情况下不超过 10%)。总的碎片率，另一方面，不应低于几千赫因为有关多重碎裂通路的份额通常是小于 10-4。同样令人鼓舞的事实，应该提到的是原则单一碎片事件已足以识别的光学纯样品，配置和检测几百允许确定的对映异构体中丰度未知的对映体组成的样品。

<table border="0" cellpadding="0" cellspacing="0" width="599">
	<tbody>
		<tr height="31">
			<td height="31" style="height:31px;width:179px;">CHBrCl2</td>
			<td style="width:93px;">SigmaAldrich</td>
			<td style="width:147px;">139181-10G</td>
			<td style="width:180px;">or other suitable sample</td>
		</tr>
		<tr height="31">
			<td height="31" style="height:31px;width:179px;">femtosecond laser system</td>
			<td>KMLabs</td>
			<td style="width:147px;">Wyvern500</td>
			<td style="width:180px;"></td>
		</tr>
		<tr height="31">
			<td height="31" style="height:31px;width:179px;">High-reflective mirrors</td>
			<td>EKSMA</td>
			<td style="width:147px;">042-0800</td>
			<td style="width:180px;"></td>
		</tr>
		<tr height="31">
			<td height="31" style="height:31px;width:179px;">mirror mounts</td>
			<td>Newport</td>
			<td style="width:147px;">U100-A-LH-2K&#160;&#160;</td>
			<td style="width:180px;"></td>
		</tr>
		<tr height="35">
			<td height="35" style="height:35px;width:179px;">focusing mirror (protected silver, f = 75 mm)</td>
			<td>Thorlabs&#160;</td>
			<td style="width:147px;">CM254-075-P01</td>
			<td style="width:180px;">(if available: f = 60 mm)</td>
		</tr>
		<tr height="51">
			<td height="51" style="height:51px;width:179px;">COLTRIMS spectrometer, including electronics and data acquisition system</td>
			<td>RoentDek</td>
			<td style="width:147px;">custom</td>
			<td style="width:180px;">contrary to the standard COLTRIMS, only one detector is needed</td>
		</tr>
	</tbody>
</table>

coulomb explosion imaging as a tool to distinguish between stereoisomers

这篇文章显示了如何使用 COLTRIMS （冷目标反冲离子动量谱仪） 或"反应显微镜"技术来区分对映体 （立体异构体） 的单个分子水平上的简单手性物种。在此方法中，样品的气体分子射流扩展进入真空室和飞秒 (fs) 激光脉冲与相交。高强度的脉冲会导致快速多个电离，点燃了所谓的库仑爆炸，产生几个阳离子 （正电） 片段。静电场指导这些阳离子时间和位置灵敏探测器上。类似于飞行时间质谱仪，每个离子的到达时间产生于它的质量信息。如有盈余，静电场被调整中，发射方向和动能后碎片导致变异在飞行时间和影响位置探测器的一种方式。
每个离子影响创建电子信号在探测器;这个信号是治疗高频率电子和计算机记录事件的事件。注册的数据对应的影响时间和位置。面对这些数据，可以计算能量和每个片段的发射方向。这些值是根据调查，即对债券长度和相对位置的原子，允许以确定分子通过分子的手性的简单手性物种和其他同分异构体的功能分子的结构性质有关。

在这一部分中，我们显示结果的应用。这些种类的原理验证实验由于其简单性和蒸汽压力高的理想选择。同时，利用同步辐射光源的软 x 射线光子诱导多个电离研究了更复杂的物种氟烷。14
CHBrClF
Bromochlorofluoromethane (CHBrClF) 是一个教科书例子为手性分子与手性碳原?...

Watch this Scientific Journal Video about Coulomb Explosion Imaging as a Tool to Distinguish Between Stereoisomers at JoVE.com

Coulomb Explosion Imaging as a Tool to Distinguish Between Stereoisomers

作为一种工具来区分立体异构体的库仑爆炸成像

小手性的物种，库仑爆炸成像提供了新的途径来确定单个分子的手性。

This article shows how the COLTRIMS (Cold Target Recoil Ion Momentum Spectroscopy) or the "reaction microscope" technique can be used to distinguish ...

coulomb-explosion-imaging-as-tool-to-distinguish-between

Education

Research

JoVE Core

JoVE Journal

Organic Chemistry

Chemistry

Unit 1

Transition Metals and Coordination Complexes

Stereoisomerism

SCIENTISTS IN ACTION

9.0K 次观看.  Goethe-Universität Frankfurt am Main. 小手性的物种，库仑爆炸成像提供了新的途径来确定单个分子的手性。

视频: Coulomb Explosion Imaging as a Tool to Distinguish Between Stereoisomers

Rapid Colorimetric Assays to Qualitatively Distinguish RNA and DNA in Biomolecular Samples

Biochemical experimentation generally requires accurate knowledge, at an early stage, of the nucleic acid, protein, and other biomolecular components in potentially heterogeneous specimens. Nucleic acids can be detected via several established approaches, including analytical methods that are spectrophotometric (e.g., A260), fluorometric (e.g., binding of fluorescent dyes), or colorimetric (nucleoside-specific chromogenic chemical reactions).1 Though it cannot readily distinguish RNA from DNA, the A260/A280 ratio is commonly employed, as it offers a simple and rapid2 assessment of the relative content of nucleic acid, which absorbs predominantly near 260 nm and protein, which absorbs primarily near 280 nm. Ratios &lt; 0.8 are taken as indicative of 'pure' protein specimens, while pure nucleic acid (NA) is characterized by ratios &gt; 1.53.
However, there are scenarios in which the protein/NA content cannot be as clearly or reliably inferred from simple uv-vis spectrophotometric measurements. For instance, (i) samples may contain one or more proteins which are relatively devoid of the aromatic amino acids responsible for absorption at &asymp;280 nm (Trp, Tyr, Phe), as is the case with some small RNA-binding proteins, and (ii) samples can exhibit intermediate A260/A280 ratios (~0.8 &lt; ~1.5), where the protein/NA content is far less clear and may even reflect some high-affinity association between the protein and NA components. For such scenarios, we describe herein a suite of colorimetric assays to rapidly distinguish RNA, DNA, and reducing sugars in a potentially mixed sample of biomolecules. The methods rely on the differential sensitivity of pentoses and other carbohydrates to Benedict's, Bial's (orcinol), and Dische's (diphenylamine) reagents; the streamlined protocols can be completed in a matter of minutes, without any additional steps of having to isolate the components. The assays can be performed in parallel to differentiate between RNA and DNA, as well as indicate the presence of free reducing sugars such as glucose, fructose, and ribose (Figure 1).

A suite of colorimetric assays is described for rapidly distinguishing protein, RNA, DNA, and reducing sugars in potentially heterogeneous biomolecular samples.

快速比色测定RNA和DNA生物分子样品进行定性区分

Biochemical experimentation generally requires accurate knowledge, at an early stage, of the nucleic acid, protein, and other biomolecular components in ...

科研

化学

Real-time Monitoring of Reactions Performed Using Continuous-flow Processing: The Preparation of 3-Acetylcoumarin as an Example

By using inline monitoring, it is possible to optimize reactions performed using continuous-flow processing in a simple and rapid way. It is also possible to ensure consistent product quality over time using this technique. We here show how to interface a commercially available flow unit with a Raman spectrometer. The Raman flow cell is placed after the back-pressure regulator, meaning that it can be operated at atmospheric pressure. In addition, the fact that the product stream passes through a length of tubing before entering the flow cell means that the material is at RT. It is important that the spectra are acquired under isothermal conditions since Raman signal intensity is temperature dependent. Having assembled the apparatus, we then show how to monitor a chemical reaction, the piperidine-catalyzed synthesis of 3-acetylcoumarin from salicylaldehyde and ethyl acetoacetate being used as an example. The reaction can be performed over a range of flow rates and temperatures, the in-situ monitoring tool being used to optimize conditions simply and easily.

Real-time monitoring allows for fast optimization of reactions performed using continuous-flow processing. Here the preparation of 3-acetylcoumarin is used as an example. The apparatus for performing in-situ Raman monitoring is described, as are the steps required to optimize the reaction.

反应执行使用连续流处理的实时监控:3  - 乙酰基香豆素的制备为例

By using inline monitoring, it is possible to optimize reactions performed using continuous-flow processing in a simple and rapid way. It is also possible ...

Deacetylation Assays to Unravel the Interplay between Sirtuins (SIRT2) and Specific Protein-substrates

Acetylation has emerged as an important post-translational modification (PTM) regulating a plethora of cellular processes and functions. This is further supported by recent findings in high-resolution mass spectrometry based proteomics showing that many new proteins and sites within these proteins can be acetylated. However the identity of the enzymes regulating these proteins and sites is often unknown. Among these enzymes, sirtuins, which belong to the class III histone lysine deacetylases, have attracted great interest as enzymes regulating the acetylome under different physiological or pathophysiological conditions. Here we describe methods to link SIRT2, the cytoplasmic sirtuin, with its substrates including both in vitro and in vivo deacetylation assays. These assays can be applied in studies focused on other members of the sirtuin family to unravel the specific role of sirtuins and are necessary in order to establish the regulatory interplay of specific deacetylases with their substrates as a first step to better understand the role of protein acetylation. Furthermore, such assays can be used to distinguish functional acetylation sites on a protein from what may be non-regulatory acetylated lysines, as well as to examine the interplay between a deacetylase and its substrate in a physiological context.

Deacetylation Assays to Unravel the Interplay between Sirtuins SIRT2 and Specific Protein-substrates

This protocol describes the required steps to execute in vitro and in vivo deacetylation assays in order to establish the role of proteins as specific deacetylation substrates for sirtuins and further study the role of reversible - lysine acetylation as a post-translational modification.

脱乙酰测定解开蛋白特异底物乙酰化酶之间的Interplay（SIRT2）和

Acetylation has emerged as an important post-translational modification (PTM) regulating a plethora of cellular processes and functions. This is further ...

Spin Saturation Transfer Difference NMR (SSTD NMR): A New Tool to Obtain Kinetic Parameters of Chemical Exchange Processes

This detailed protocol describes the new Spin Saturation Transfer Difference Nuclear Magnetic Resonance protocol (SSTD NMR), recently developed in our group to study processes of mutual-site chemical exchange that are difficult to analyze by traditional methods. As the name suggests, this method combines the Spin Saturation Transfer method used for small molecules, with the Saturation Transfer Difference (STD) NMR method employed for the study of protein-ligand interactions, by measuring transient spin saturation transfer along increasing saturation times (build-up curves) in small organic and organometallic molecules undergoing chemical exchange.
Advantages of this method over existing ones are: there is no need to reach coalescence of the exchanging signals; the method can be applied as long as one signal of the exchanging sites is isolated; there is no need to measure T1 or reach steady state saturation; rate constant values are measured directly, and T1 values are obtained in the same experiment, using only one set of experiments.
To test the method, we have studied the dynamics of the hindered rotation of N,N-dimethylamides, for which much data is available for comparison. The thermodynamic parameters obtained using SSTD are very similar to the reported ones (spin-saturation transfer techniques and line-shape analysis). The method can be applied to more challenging substrates that cannot be studied by previous methods.
We envisage that the simple experimental set up and the wide applicability of the method to a great variety of substrates will make this a common technique amongst organic and organometallic chemists without extensive expertise in NMR.

Spin Saturation Transfer Difference NMR SSTD NMR: A New Tool to Obtain Kinetic Parameters of Chemical Exchange Processes

A detailed protocol describing the SSTD NMR method is presented here to help new users apply this new method to obtain the kinetic parameters of their own systems undergoing chemical exchange.

自旋饱和转移差异核磁共振（NMR SSTD）:一种新的工具来获得化学交换过程的动力学参数

This detailed protocol describes the new Spin Saturation Transfer Difference Nuclear Magnetic Resonance protocol (SSTD NMR), recently developed in our ...

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). ...

Color Spot Test As a Presumptive Tool for the Rapid Detection of Synthetic Cathinones

Synthetic cathinones are a large class of new psychoactive substances (NPS) that are increasingly prevalent in drug seizures made by law enforcement and other border protection agencies globally. Color testing is a presumptive identification technique indicating the presence or absence of a particular drug class using rapid and uncomplicated chemical methods. Owing to their relatively recent emergence, a color test for the specific identification of synthetic cathinones is not currently available. In this study, we introduce a protocol for the presumptive identification of synthetic cathinones, employing three aqueous reagent solutions: copper(II) nitrate, 2,9-dimethyl-1,10-phenanthroline (neocuproine) and sodium acetate. Small pin-head sized amounts (approximately 0.1-0.2 mg) of the suspected drugs are added to the wells of a porcelain spot plate, and each reagent is then added dropwise sequentially before heating on a hotplate. A color change from very light blue to yellow-orange after 10 min indicates the likely presence of synthetic cathinones. The highly stable and specific test reagent has the potential for use in the presumptive screening of unknown samples for synthetic cathinones in a forensic laboratory. However, the nuisance of an added heating step for the color change result limits the test to laboratory application and decreases the likelihood of an easy translation to field testing.

Here we present a simple, inexpensive, and selective chemical spot test protocol for the detection of synthetic cathinones, a class of new psychoactive substances. The protocol is suitable for use in various areas of law enforcement that encounter illicit material.

色斑试验作为合成 Cathinones 快速检测的推定工具

Synthetic cathinones are a large class of new psychoactive substances (NPS) that are increasingly prevalent in drug seizures made by law enforcement and ...

Automation of a Positron-emission Tomography (PET) Radiotracer Synthesis Protocol for Clinical Production

The development of new positron-emission tomography (PET) tracers is enabling researchers and clinicians to image an increasingly wide array of biological targets and processes. However, the increasing number of different tracers creates challenges for their production at radiopharmacies. While historically it has been practical to dedicate a custom-configured radiosynthesizer and hot cell for the repeated production of each individual tracer, it is becoming necessary to change this workflow. Recent commercial radiosynthesizers based on disposable cassettes/kits for each tracer simplify the production of multiple tracers with one set of equipment by eliminating the need for custom tracer-specific modifications. Furthermore, some of these radiosynthesizers enable the operator to develop and optimize their own synthesis protocols in addition to purchasing commercially-available kits. In this protocol, we describe the general procedure for how the manual synthesis of a new PET tracer can be automated on one of these radiosynthesizers and validated for the production of clinical-grade tracers. As an example, we use the ELIXYS radiosynthesizer, a flexible cassette-based radiochemistry tool that can support both PET tracer development efforts, as well as routine clinical probe manufacturing on the same system, to produce [18F]Clofarabine ([18F]CFA), a PET tracer to measure in vivo deoxycytidine kinase (dCK) enzyme activity. Translating a manual synthesis involves breaking down the synthetic protocol into basic radiochemistry processes that are then translated into intuitive chemistry &#34;unit operations&#34; supported by the synthesizer software. These operations can then rapidly be converted into an automated synthesis program by assembling them using the drag-and-drop interface. After basic testing, the synthesis and purification procedure may require optimization to achieve the desired yield and purity. Once the desired performance is achieved, a validation of the synthesis is carried out to determine its suitability for the production of the radiotracer for clinical use.

Automation of a Positron-emission Tomography PET Radiotracer Synthesis Protocol for Clinical Production

Positron-emission tomography (PET) imaging sites that are involved in multiple early clinical research trials need robust and versatile radiotracer manufacturing capabilities. Using the radiotracer [18F]Clofarabine as an example, we illustrate how to automate the synthesis of a radiotracer using a flexible, cassette-based radiosynthesizer and validate the synthesis for clinical use.

用于临床生产的正电子发射层析成像 (PET) 放射性同位素示踪合成协议的自动化

The development of new positron-emission tomography (PET) tracers is enabling researchers and clinicians to image an increasingly wide array of biological ...

Solid Phase 11C-Methylation, Purification and Formulation for the Production of PET Tracers

Routine production of radiotracers used in positron emission tomography (PET) mostly relies on wet chemistry where the radioactive synthon reacts with a non-radioactive precursor in solution. This approach necessitates purification of the tracer by high performance liquid chromatography (HPLC) followed by reformulation in a biocompatible solvent for human administration. We recently developed a novel 11C-methylation approach for the highly efficient synthesis of carbon-11 labeled PET radiopharmaceuticals, taking advantage of solid phase cartridges as disposable &#34;3-in-1&#34; units for the synthesis, purification and reformulation of the tracers. This approach obviates the use of preparative HPLC and reduces the losses of the tracer in transfer lines and due to radioactive decay. Furthermore, the cartridge-based technique improves synthesis reliability, simplifies the automation process and facilitates compliance with the Good Manufacturing Practice (GMP) requirements. Here, we demonstrate this technique on the example of production of a PET tracer Pittsburgh compound B ([11C]PiB), a gold standard in vivo imaging agent for amyloid plaques in the human brains.

Solid Phase 11C-Methylation, Purification and Formulation for the Production of PET Tracers

We report an efficient carbon-11 radiolabeling technique to produce clinically relevant tracers for Positron Emission Tomography (PET) using solid phase extraction cartridges. 11C-methylating agent is passed through a cartridge preloaded with precursor and successive elution with aqueous ethanol provides chemically and radiochemically pure PET tracers in high radiochemical yields.

用于生产PET示踪剂的固体阶段11C甲基化、纯化和配方

Routine production of radiotracers used in positron emission tomography (PET) mostly relies on wet chemistry where the radioactive synthon reacts with a ...

In situ FTIR Spectroscopy as a Tool for Investigation of Gas/Solid Interaction: Water-Enhanced CO2 Adsorption in UiO-66 Metal-Organic Framework

In situ infrared spectroscopy is an inexpensive, highly sensitive, and selective valuable tool to investigate the interaction of polycrystalline solids with adsorbates. Vibrational spectra provide information on the chemical nature of adsorbed species and their structure. Thus, they are very useful for obtaining molecular level understanding of surface species. The IR spectrum of the sample itself gives some direct information about the material. General conclusions can be drawn concerning hydroxyl groups, some stable surface species and impurities. However, the spectrum of the sample is &#34;blind&#34; with respect to the presence of coordinatively unsaturated ions and gives rather poor information about the acidity of surface hydroxyls, species decisive for the adsorption and catalytic properties of the materials. Furthermore, no discrimination between bulk and surface species can be made. These problems are solved by the use of probe molecules, substances that interact specifically with the surface; the alteration of some spectral features of these molecules as a result of adsorption provides valuable information about the nature, properties, location, concentration, etc., of the surface sites.
The experimental protocol for in-situ IR studies of gas/sample interaction includes preparation of a sample pellet, activation of the material, initial spectral characterization through the analysis of the background spectra, characterization by probe molecules, and study of the interaction with a particular set of gas mixtures. In this paper we investigate a zirconium terephthalate metal organic framework, Zr6O4(OH)4(BDC)6 (BDC = benzene-1,4-dicarboxylate), namely UiO-66 (UiO refers to University of Oslo). The acid sites of the UiO-66 sample are determined by using CO and CD3CN as molecular probes. Furthermore, we have demonstrated that CO2 is adsorbed on basic sites exposed on dehydroxylated UiO-66. Introduction of water to the system produces hydroxyl groups acting as additional CO2 adsorption sites. As a result, CO2 adsorption capacity of the sample is strongly enhanced.

In situ FTIR Spectroscopy as a Tool for Investigation of Gas/Solid Interaction: Water-Enhanced CO2 Adsorption in UiO-66 Metal-Organic Framework

The use of FTIR spectroscopy for investigation of the surface properties of polycrystalline solids is described. Preparation of sample pellets, activation procedures, characterization with probe molecules and model studies of CO2 adsorption are discussed.

原位FTIR 光谱作为气体/固体相互作用研究工具:UiO-66 金属-有机框架中的水增强 CO2吸附

In situ infrared spectroscopy is an inexpensive, highly sensitive, and selective valuable tool to investigate the interaction of polycrystalline solids ...

作为一种工具来区分立体异构体的库仑爆炸成像

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