SR承认以色列科学基金会的支持下，不授予。十二分之二百八十零。

1，准备样品的碳<ol><li>磨碎碳样品所需部分尺寸（在此，煤样品研磨成之间74-250毫米的分数大小）。 </li><li>在磨削过程中砂轮机应在规范的环境中举行（AC冷却到20°C）。此外，吹扫研磨室用氮气之前研磨的流动在此阶段最小化氧化。 </li><li>转移碳样品可密封罐和更换空气气氛氮气。保持样本中的温度调节室（AC冷却至20℃）。 </li><li>通过在真空炉中加热该碳样品在惰性环境下制备的碳样品的EPR测量。 （为了除去吸附的水而制得。） </li><li>将每个样品在真空烘箱内开放的玻璃小瓶中（ 图1A）。 </li><li>关闭真空烤箱门，更换气氛在室内无线个氮气或氩气，然后加热至60℃。 </li><li>保持这些条件下放置24小时。 </li><li>关闭烘箱，并允许温度达到室温。然后，打开烤箱，取出样品瓶。 </li><li>塞子用橡胶隔片和铝盖（ 图1B）的样品小瓶中。 </li><li>使用真空系统（ 图1C），以除去氧气的所有痕迹。 </li><li>药瓶连接到系统并密封阀1-5。 </li><li>打开真空泵和压力表。 </li><li>打开阀1，等到显示器显示〜0.1毫巴的真空。 </li><li>确保泄漏极小，通过关闭阀1和计数到30，如果压力增加不大于3毫巴比系统的密封是足够的。 </li><li>开阀2和除去大气中的小瓶 - 等到压力返回到步骤1.14确定的初始压力值，并再次测试渗漏。 </li><li>如果有多个小瓶是贝因克做在同一时间（阀2-4）然后重复步骤1.15为每个阀门。 </li><li>实现真空和有效地清除剩余的气氛的小瓶中后，以期望的气体代替大气。 </li><li>关闭阀1，立即打开阀门5，让压力达到0.5个大气压。 </li><li>关闭阀5和开阀1，除​​去气体，等到返回到起始真空阀（吹扫1）。 </li><li>关闭阀1，立即打开阀门5，让压力达到0.5个大气压。 </li><li>关闭阀5，开阀1，除​​去气体，等到返回到起始真空阀（吹扫2）。 </li><li>关闭阀1，立即打开阀门5，让压力达到1.0个大气压，然后关闭阀门5。 </li><li>关闭阀2和向下轻轻拔出该针取出小瓶。 </li><li>除去小瓶打开阀1和后，从真空系统中清除的气体。 </li><li>在关闭真空泵，开阀2，以允许空气进入系统，并同时关闭所述泵（这防止了油的回流）。 </li></ol> 2，装入EPR3毫米石英管<ol><li>冲洗管的EPR用乙醇和干燥与N 2。 </li><li>从所需的煤样去除铝密封件。 </li><li>轻轻转动EPR管的开口端插入填充有碳样品的小瓶中。 </li><li>按下并转动EPR管，然后轻轻拍打，直到试样均匀分散在底部。 </li><li>填充管以这种方式高达至少1.5厘米的长度。 </li><li>轴封采用腻子约0.5-1.0厘米长（ 图2A）的橡胶腻子铁氟龙管的末端。 </li></ol> 3，设置流动系统<ol><li>将石英管放入EPR谐振器，请确保EPR管装满煤的部分填满整个谐振腔。 </li><li>这里报道的EPR测量是CONDucted在室温292-297 K。 </li><li>设置一个罐用所需流量的气体（N 2，CO 2，赫）确保有2个操作阀门，以控制流动（ 图2B）。 </li><li>连接橡胶管连接到油箱。确保该长度达到EPR石英管具有足够的拉力的前端，以便不把应变在石英管中。 </li><li>一个流量控制器连接到橡胶管来监测气体流动。 </li><li>通过使用小针头插入管通过橡胶特氟隆腻子。 </li><li>插入针头，直到它在接近（约3-4厘米以上的煤表面）的样品，但足够远从样品以免影响磁场（ 图2C）。 </li><li>离开流关闭（调整后只能打开流量）。 </li><li>戳在橡胶腻子的孔释放流出气体。 </li></ol> 4。EPR测量<ol><li>打开EPR谱仪之三。 </li><li>调整，没有气流。打开微波炉调节面板，找到浸达33.0 dB的功率，并使用自动调谐以获得最佳的调谐条件.. </li><li>将微波功率为2.0毫瓦，在这个功率没有饱和。 </li><li>开2D实验中，作为磁场和时间的函数。 </li><li>设置实验的参数如下: 微波功率为2.0毫瓦 调制振幅= 1.0克 时间常数= 60毫秒 扫描宽度= 100g的 延迟= 120秒 点的场扫描扫描= 1024号 点号作为时间= 50的函数</li><li>开始测量周期。 </li><li>打开气体流动。 </li><li>在样品达到平衡，并没有进一步的变化在EPR线的形状，这些参数后，分别测量它们之间的120秒的延迟，大约25 CW-EPR谱，停止气体流动。样品暴露在大气中，并继续进行测量，直到50秒pectra获得，或直至达到平衡。有停止燃气的流量后不需要再调整。测量自动继续，每个CW-EPR谱之间120秒的延迟。 </li><li>如果到达以较慢的速度平衡，增加点的数量作为时间的函数。 </li><li>如果达到以更快的速度的平衡，减少每次扫描之间的延迟时间。 </li></ol> 5。数据分析<ol><li>模拟使用MATLAB的23实施easyspin工具箱每个EPR场扫描光谱。采取两种考虑，在每个物种的g值，线宽，以及电子顺磁共振谱的贡献程度装有通过编写程序文件，如下所示: 清晰，CLF，CLC ％负载实验文件 expdata =负载（&#39;t0s.txt&#39;）; ％定义的物种一个自旋系统 SysC.g = 2.004; SysC.lwpp = 0.62; ％定义实验参数规格IES 1 Exp.mwFreq = 9.85764; ％以GHz Exp.Range = [347 357]; ％为mT Exp.Harmonic = 1; ％计算连续波EPR谱的生物种类之一 [BX，specX] =辣椒（SYSC，地契）; ％定义物种两个自旋系统 SysC2.g = 2.0028; SysC2.lwpp = 0.145; ％定义实验参数进行种内的两个 Exp2.mwFreq = 9.85764; Exp2.Range = [347 357]; Exp2.Harmonic = 1; ％计算连续波EPR谱种的两个 [BX2，specX2] =辣椒（SysC2，Exp2后）; X = 0:0.1:1; ％结合两个物种的光谱。 spectot = 1.0 * specX +0.0 * specX2; ％绘制实验和模拟光谱。 BX * 10，spectot，expdata（:，1），expdata（:，2））; </li></ol>

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没有利益冲突的声明。

碳材料的表面氧化是显著的工业和学术兴趣。碳底物氧化的影响已被鉴定具有广泛的分析技术，包括EPR。当调查的分子氧与碳基材如煤具有倾向发生氧化（因此它主要利用作为能源资源）的相互作用的样品制备和储存是极其重要的。 我们的样品是已经海外运送大型货舱为能源行业的煤炭利用基板。即使该样品在运输过程中由于发生一些氧化，我们试图通过随后将它们存储在N ...

不同的C / H / O原子（重量％）的比率基板目前不同类型和稳定的自由基，通过电子顺磁共振（EPR）是检测到的浓度8。这些基团依赖于大分子的结构和它们的芳族性质的高度影响。煤自由基的EPR光谱，其特征在于由单一的宽共振。在这种情况下，只对g值时，线条宽度和自旋浓度可以得到。 EPR谱的G-值可以被用于确定是否一个基是碳中心或氧为中心的。基本方程为电子塞曼相互作用<img alt="式（1）" fo:content-width="0.8in" src="/files/ftp_upload/51548/51548eq1.jpg" />定义的g值，其中h是普朗克常数，v是在实验中所施加的恒定MW频率，B 0是谐振磁场和βe为玻尔磁子。对于自由电子的g值是2.00232。 V在从2.00232的g值ariations涉及涉及未成对电子的轨道角动量，其化学环境的磁相互作用。有机基团通常具有G-值接近自由电子克，这取决于自由基在有机基质3，8-10的位置。碳中心自由基具有G-值是接近自由电子的g值2.0023。碳中心自由基与相邻的氧原子具有在2.003-2.004范围内较高的G-值，而中心的氧自由基具有G-数值&gt; 2.004。为2.0034-2.0039的g值的特征是碳中心自由基在附近的氧杂原子而导致增加的G-值较纯碳中心自由基11-15。线宽是由自旋 - 晶格驰豫过程支配。因此，相邻的基团之间或自由基与顺磁氧导致的减少之间的相互作用在自旋晶格弛豫时间，并因此增加了线宽4-6。 停止流动的实验与EPR检测允许观察在EPR信号在两个阶段通过时间扫描采集（动能显示）的相互作用过程中一个独特的字段值的振幅随时间变化。这种测量的结果是一个速率常数的形成，腐烂或转换的顺磁性物质。该过程是类似的完善与其中的光吸收在一个独特的波长的时间依赖性，观察光检测停止流的操作的情况。典型地停止流动实验以液体状态进行与未EPR在液体状态检测由于短的弛豫时间T 1的基团，如，例如羟基（OH×）或超氧化物（O 2 - ）不能直接由EPR-停止研究流技术。它是，但是，possibl<html> e来研究自旋加合物，这些基团与硝酮，产生氮氧自由基型（自旋过滤器），因为它们是EPR-活性和它们的动力学也可以监视由停止流动EPR 16-18。 利用快速流动的气体的技术与EPR检测化学反应速率的测量方法也曾被证实19-22。在本质上，该方法依赖于测量，通过EPR，反应物作为距离的函数的浓度（并因此以恒定的速度，时间）超过该反应物已在与反应气体接触的流管。条件，使反应气体的浓度是大致恒定的，通常采用使测得的衰减是假一级。 在目前的工作中，一个简单的气体流量设置实施和气体的恒定流量被引入到固体碳基体的表面。 ntent"&gt;有在当前工作中详述的方法，我们成功地实现了，其中分子氧与现有的稳定的自由基结构的某一部分的这种相互作用可以被可逆地简单地受到通过在STP下的碳样品流过一个反磁性气体有趣的结果。作为这种方法的结果是除去相互作用的顺磁性气体的揭示了新的基面有g值，这是更接近于自由电子。

<table><tbody><tr><td>EPR spectrometer</td><td>Bruker</td><td>Elexsys E500</td><td></td></tr><tr><td>EPR quartz tube</td><td>Wilmad-Lab Glass</td><td></td><td></td></tr><tr><td>Vacuum oven&amp;nbsp;</td><td>Heraeus</td><td>VT6060</td><td></td></tr><tr><td>Balance</td><td>Denver Instrument</td><td>100A</td><td></td></tr><tr><td>High Vacuum Silicone Grease</td><td>VWR International</td><td>59344-055</td><td></td></tr><tr><td>Teflon putty&amp;nbsp;</td><td></td><td></td><td></td></tr><tr><td>Laboratory (Rubber) Stoppers</td><td>Sigma-Aldrich</td><td>Z114111</td><td></td></tr><tr><td>Aluminum Crimp seals&amp;nbsp;</td><td>Sigma-Aldrich</td><td>Z114146</td><td></td></tr><tr><td>Hand Crimper</td><td>Sigma-Aldrich</td><td>Z114243</td><td></td></tr><tr><td>Borosilicate vials&amp;nbsp;</td><td>Sigma-Aldrich</td><td>Z11938</td><td></td></tr><tr><td>Rubber tubing&amp;nbsp;</td><td></td><td></td><td></td></tr><tr><td>Aluminum hose clamps</td><td></td><td></td><td></td></tr><tr><td>Screwdriver&amp;nbsp;</td><td></td><td></td><td></td></tr><tr><td>Custom made vacuum system&amp;nbsp;</td><td></td><td></td><td></td></tr><tr><td>Glass storage cylinders&amp;nbsp;</td><td></td><td></td><td></td></tr><tr><td>BD Regular Bevel Needles</td><td>BD</td><td>305122</td><td></td></tr><tr><td>Helium&amp;nbsp;&amp;nbsp;</td><td>Oxar Ltd</td><td></td><td></td></tr><tr><td>Argon&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;</td><td>Oxar Ltd</td><td></td><td></td></tr><tr><td>CO&lt;sub&gt;2&lt;/sub&gt; 99.99%</td><td>Maxima</td><td></td><td></td></tr><tr><td>N&lt;sub&gt;2&lt;/sub&gt; 99.999%</td><td>Oxar Ltd</td><td></td><td></td></tr><tr><td>O&lt;sub&gt;2&lt;/sub&gt;</td><td>Maxima</td><td></td><td></td></tr><tr><td>Air</td><td>Maxima</td><td></td><td></td></tr></tbody></table>

exploring the radical nature of a carbon surface by electron paramagnetic resonance and a calibrated gas flow

虽然第一电子顺磁共振（EPR）就氧化碳自由基的结构和稳定性影响的研究可以追溯到20世纪80年代初的早期论文的焦点主要特征的变化对结构极其恶劣的条件下（pH值或温度）1-3。它也被称为顺磁性分子氧经过与稳定自由基的海森堡自旋交换作用是极其开阔的EPR信号4-6。最近，我们报道，其中分子氧与现有的稳定的自由基结构的某一部分的这种相互作用可以被可逆地简单地受到通过在STP 7的碳样品流过一个反磁性气体有趣的结果。例如He，CO 2和N 2的流量也有类似的影响这些相互作用发生在大孔体系的表面积。 这个手稿突出了实验吨echniques，工作起来，对影响碳结构的现有稳定的自由基性质分析。希望这将有助于对在社区这些互动的在逃进一步发展和理解。

当预成型的各类煤样的EPR实验，作为曝光时间的函数的反磁性气体流有人指出，气体流动过程中，第二个物种在g〜2.0028出现。这g值是接近自由电子的值，并与未取代的脂族碳中心自由基一致。然而，总自旋浓度为每一个样品我们的实验误差范围内保持恒定（±10％） 图3A给出两个扫描:0秒和1,900秒后煤样已暴露于CO 2气体（HA）。电子顺磁共振谱1,900秒的特点是两个物种。一个在...

Watch this Scientific Journal Video about Exploring the Radical Nature of a Carbon Surface by Electron Paramagnetic Resonance and a Calibrated Gas Flow at JoVE.com

Exploring the Radical Nature of a Carbon Surface by Electron Paramagnetic Resonance and a Calibrated Gas Flow

稳定自由基存在于碳底物通过海森堡自旋交换与顺磁氧相互作用。这种相互作用可以显著STP条件下，通过在碳制流动的反磁性气体减少。这个手稿描述了一个简单的方法来描述这些自由基的性质。

通过电子顺磁共振和校准气体流量探索碳表面的激进性质

While the first Electron Paramagnetic Resonance (EPR) studies regarding the effects of oxidation on the structure and stability of carbon radicals date ...

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10.7K 次观看.  The Hebrew University of Jerusalem. 稳定自由基存在于碳底物通过海森堡自旋交换与顺磁氧相互作用。这种相互作用可以显著STP条件下，通过在碳制流动的反磁性气体减少。这个手稿描述了一个简单的方法来描述这些自由基的性质。 

视频: Exploring the Radical Nature of a Carbon Surface by Electron Paramagnetic Resonance and a Calibrated Gas Flow

A Protocol for Detecting and Scavenging Gas-phase Free Radicals in Mainstream Cigarette Smoke

Cigarette smoking is associated with human cancers. It has been reported that most of the lung cancer deaths are caused by cigarette smoking 5,6,7,12. Although tobacco tars and related products in the particle phase of cigarette smoke are major causes of carcinogenic and mutagenic related diseases, cigarette smoke contains significant amounts of free radicals that are also considered as an important group of carcinogens9,10. Free radicals attack cell constituents by damaging protein structure, lipids and DNA sequences and increase the risks of developing various types of cancers. Inhaled radicals produce adducts that contribute to many of the negative health effects of tobacco smoke in the lung3. Studies have been conducted to reduce free radicals in cigarette smoke to decrease risks of the smoking-induced damage. It has been reported that haemoglobin and heme-containing compounds could partially scavenge nitric oxide, reactive oxidants and carcinogenic volatile nitrosocompounds of cigarette smoke4. A 'bio-filter' consisted of haemoglobin and activated carbon was used to scavenge the free radicals and to remove up to 90% of the free radicals from cigarette smoke14. However, due to the cost-ineffectiveness, it has not been successfully commercialized. Another study showed good scavenging efficiency of shikonin, a component of Chinese herbal medicine8. In the present study, we report a protocol for introducing common natural antioxidant extracts into the cigarette filter for scavenging gas phase free radicals in cigarette smoke and measurement of the scavenge effect on gas phase free radicals in mainstream cigarette smoke (MCS) using spin-trapping Electron Spin Resonance (ESR) Spectroscopy1,2,14. We showed high scavenging capacity of lycopene and grape seed extract which could point to their future application in cigarette filters. An important advantage of these prospective scavengers is that they can be obtained in large quantities from byproducts of tomato or wine industry respectively11,13

Spin-trapping ESR spectroscopy was used to study the effect of plant antioxidants lycopene, pycnogenol and grape seed extract on scavenging gas-phase free radicals in cigarette smoke.

卷烟主流烟气中检测和清除气相自由基议定书

Cigarette smoking is associated with human cancers. It has been reported that most of the lung cancer deaths are caused by cigarette smoking 5,6,7,12.  ...

科研

生物工程

Measurement of Ultrafast Vibrational Coherences in Polyatomic Radical Cations with Strong-Field Adiabatic Ionization

We present a pump-probe method for preparing vibrational coherences in polyatomic radical cations and probing their ultrafast dynamics. By shifting the wavelength of the strong-field ionizing pump pulse from the commonly used 800 nm into the near-infrared (1200-1600 nm), the contribution of adiabatic electron tunneling to the ionization process increases relative to multiphoton absorption. Adiabatic ionization results in predominant population of the ground electronic state of the ion upon electron removal, which effectively prepares a coherent vibrational state (&#34;wave packet&#34;) amenable to subsequent excitation. In our experiments, the coherent vibrational dynamics are probed with a weak-field 800 nm pulse and the time-dependent yields of dissociation products measured in a time-of-flight mass spectrometer. We present the measurements on the molecule dimethyl methylphosphonate (DMMP) to illustrate how using 1500 nm pulses for excitation enhances the amplitude of coherent oscillations in ion yields by a factor of 10 as compared to 800 nm pulses. This protocol may be implemented in existing pump-probe setups through the incorporation of an optical parametric amplifier (OPA) for wavelength conversion.

We present a protocol for probing ultrafast vibrational coherences in polyatomic radical cations that result in molecular dissociation.

强场绝热电离多原子自由基阳离子超快振动相干的测量

We present a pump-probe method for preparing vibrational coherences in polyatomic radical cations and probing their ultrafast dynamics. By shifting the ...

化学

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 ...

Rapid Scan Electron Paramagnetic Resonance Opens New Avenues for Imaging Physiologically Important Parameters In Vivo

We demonstrate a superior method of 2D spectral-spatial imaging of stable radical reporter molecules at 250 MHz using rapid-scan electron-paramagnetic-resonance (RS-EPR), which can provide quantitative information under in vivo conditions on oxygen concentration, pH, redox status and concentration of signaling molecules (i.e., OH&#8226;, NO&#8226;). The RS-EPR technique has a higher sensitivity, improved spatial resolution (1 mm), and shorter acquisition time in comparison to the standard continuous wave (CW) technique. A variety of phantom configurations have been tested, with spatial resolution varying from 1 to 6 mm, and spectral width of the reporter molecules ranging from 16 &#181;T (160 mG) to 5 mT (50 G). A cross-loop bimodal resonator decouples excitation and detection, reducing the noise, while the rapid scan effect allows more power to be input to the spin system before saturation, increasing the EPR signal. This leads to a substantially higher signal-to-noise ratio than in conventional CW EPR experiments.

Rapid Scan Electron Paramagnetic Resonance Opens New Avenues for Imaging Physiologically Important Parameters In Vivo

A new electron paramagnetic resonance (EPR) method, rapid scan EPR (RS-EPR), is demonstrated for 2D spectral spatial imaging which is superior to the traditional continuous wave (CW) technique and opens new venues for in vivo imaging. Results are demonstrated at 250 MHz, but the technique is applicable at any frequency.

快速扫描电子顺磁共振打开新的途径成像生理重要参数<em&gt;在体内</em

We demonstrate a superior method of 2D spectral-spatial imaging of stable radical reporter molecules at 250 MHz using rapid-scan ...

High-Temperature and High-Pressure In situ Magic Angle Spinning Nuclear Magnetic Resonance Spectroscopy

Nuclear magnetic resonance (NMR) spectroscopy represents an important technique to understand the structure and bonding environments of molecules. There exists a drive to characterize materials under conditions relevant to the chemical process of interest. To address this, in situ high-temperature, high-pressure MAS NMR methods have been developed to enable the observation of chemical interactions over a range of pressures (vacuum to several hundred bar) and temperatures (well below 0 &#176;C to 250 &#176;C). Further, the chemical identity of the samples can be comprised of solids, liquids, and gases or mixtures of the three. The method incorporates all-zirconia NMR rotors (sample holder for MAS NMR) which can be sealed using a threaded cap to compress an O-ring. This rotor exhibits great chemical resistance, temperature compatibility, low NMR background, and can withstand high pressures. These combined factors enable it to be utilized in a wide range of system combinations, which in turn permit its use in diverse fields as carbon sequestration, catalysis, material science, geochemistry, and biology. The flexibility of this technique makes it an attractive option for scientists from numerous disciplines.

The molecular structures and dynamics of solids, liquids, gases, and mixtures are of critical interest to diverse scientific fields. High-temperature, high-pressure in situ MAS NMR enables detection of the chemical environment of constituents in mixed phase systems under tightly controlled chemical environments.

高温高压原位魔角旋转核磁共振光谱

Nuclear magnetic resonance (NMR) spectroscopy represents an important technique to understand the structure and bonding environments of molecules. There ...

Performing In Situ Closed-Cell Gas Reactions in the Transmission Electron Microscope

Gas reactions studied by in situ electron microscopy can be used to capture the real-time morphological and microchemical transformations of materials at length scales down to the atomic level. In situ closed-cell gas reaction (CCGR) studies performed using (scanning) transmission electron microscopy (STEM) can separate and identify localized dynamic reactions, which are extremely challenging to capture using other characterization techniques. For these experiments, we used a CCGR holder that utilizes microelectromechanical systems (MEMS)-based heating microchips (hereafter referred to as &#34;E-chips&#34;). The experimental protocol described here details the method for performing in situ gas reactions in dry and wet gases in an aberration-corrected STEM. This method finds relevance in many different materials systems, such as catalysis and high-temperature oxidation of structural materials at atmospheric pressure and in the presence of various gases with or without water vapor. Here, several sample preparation methods are described for various material form factors. During the reaction, mass spectra obtained with a residual gas analyzer (RGA) system with and without water vapor further validates gas exposure conditions during reactions. Integrating an RGA with an in situ CCGR-STEM system can, therefore, provide critical insight to correlate gas composition with the dynamic surface evolution of materials during reactions. In situ/operando studies using this approach allow&#160;for detailed investigation of the fundamental reaction mechanisms and kinetics that occur at specific environmental conditions (time, temperature, gas, pressure), in real-time, and at high spatial resolution.

Performing In Situ Closed-Cell Gas Reactions in the Transmission Electron Microscope

Here, we present a protocol for performing in situ TEM closed-cell gas reaction experiments while detailing several commonly used sample preparation methods.

在传输电子显微镜中执行 原位 闭电池气体反应

Gas reactions studied by in situ electron microscopy can be used to capture the real-time morphological and microchemical transformations of materials at ...

工程学

Microscopic Visualization of Porous Nanographenes Synthesized through a Combination of Solution and On-Surface Chemistry

On-surface synthesis has recently been regarded as a promising approach for the generation of new molecular structures. It has been particularly successful in the synthesis of graphene nanoribbons, nanographenes and intrinsically reactive and instable, yet attractive species. It is based on the combination of solution chemistry aimed at preparation of appropriate molecular precursors for further ultra-high vacuum surface assisted transformations. This approach also owes its success to an incredible development of characterization techniques, such as scanning tunneling/atomic force microscopy and related methods, which allow detailed, local characterization at atomic scale. While the surface-assisted synthesis can provide molecular nanostructures with outstanding precision, down to single atoms, it suffers from basing on metallic surfaces and often limited yield. Therefore, the extension of the approach away from metals and the struggle to increase productivity seem to be significant challenges toward wider applications. Herein, we demonstrate the on-surface synthesis approach for generation of non-planar nanographenes, which are synthesized through a combination of solution chemistry and sequential surface-assisted processes, together with the detailed characterization by scanning probe microscopy methods.

<meta charset="utf8"></head><body>通过溶液和表面化学相结合合成的多孔纳米石墨烯的微观可视化

A combination of solution and surface assisted synthesis opens new directions in the atomically precise synthesis of nanostructures. Scanning tunneling microscopy (STM) supplemented by non-contact atomic force microscopy (nc-AFM) enables detailed characterization of newly designed and generated carbon-based nano-objects.

通过溶液和表面化学相结合合成的多孔纳米石墨烯的微观可视化

On-surface synthesis has recently been regarded as a promising approach for the generation of new molecular structures. It has been particularly ...

Raman Spectroscopy for Chemical Analysis

Source: Laboratory of Dr. Ryoichi Ishihara &#8212; Delft University of Technology
Raman spectroscopy is a technique for analyzing vibrational and other low frequency modes in a system. In chemistry it is used to identify molecules by their Raman fingerprint. In solid-state physics it is used to characterize materials, and more specifically to investigate their crystal structure or crystallinity. Compared to other techniques for investigating the crystal structure (e.g. transmission electron microscope and x-ray diffraction) Raman micro-spectroscopy is non-destructive, generally requires no sample preparation, and can be performed on small sample volumes.
For performing Raman spectroscopy a monochromatic laser is shone on a sample. If required the sample can be coated by a transparent layer which is not Raman active (e.g., SiO2) or placed in DI water. The electromagnetic radiation (typically in the near infrared, visible, or near ultraviolet range) emitted from the sample is collected, the laser wavelength is filtered out (e.g., by a notch or bandpass filter), and the resulting light is sent through a monochromator (e.g., a grating) to a CCD detector. Using this, the inelastic scattered light, originating from Raman scattering, can be captured and used to construct the Raman spectrum of the sample.
In the case of Raman micro-spectroscopy the light passes through a microscope before reaching the sample, allowing it to be focused on an area as small as 1 &#181;m2. This allows accurate mapping of a sample, or confocal microscopy in order to investigate stacks of layers. Care has to be taken, however, that the small and intense laser spot does not damage the sample.
In this video we will briefly explain the procedure for obtaining a Raman spectra, and an example of a Raman spectrum captured from carbon nanotubes will be given.

拉曼光谱化学分析

Source: Laboratory of Dr. Ryoichi Ishihara &#8212; Delft University of Technology
Raman spectroscopy is a technique for analyzing vibrational and other ...

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Electron Paramagnetic Resonance (EPR) Spectroscopy

Source: David C. Powers, Tamara M. Powers, Texas A&#38;M
In this video, we will learn the basic principles behind Electron Paramagnetic Resonance (EPR). We will use EPR spectroscopy to study how dibutylhydroxy toluene (BHT) behaves as an antioxidant in the autoxidation of aliphatic aldehydes.

EPR Spectroscopy, Paramagnetic Molecule and Zeeman Effect

电子顺磁共振 (EPR) 光谱学

Source: David C. Powers, Tamara M. Powers, Texas A&#38;M
In this video, we will learn the basic principles behind Electron Paramagnetic Resonance (EPR). ...

通过电子顺磁共振和校准气体流量探索碳表面的激进性质

摘要

探索更多视频

此视频中的章节

卷烟主流烟气中检测和清除气相自由基议定书

强场绝热电离多原子自由基阳离子超快振动相干的测量

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

快速扫描电子顺磁共振打开新的途径成像生理重要参数

高温高压原位魔角旋转核磁共振光谱

在传输电子显微镜中执行原位闭电池气体反应

通过溶液和表面化学相结合合成的多孔纳米石墨烯的微观可视化

通过溶液和表面化学相结合合成的多孔纳米石墨烯的微观可视化

拉曼光谱化学分析

电子顺磁共振 (EPR) 光谱学

通过电子顺磁共振和校准气体流量探索碳表面的激进性质

摘要

探索更多视频

此视频中的章节

卷烟主流烟气中检测和清除气相自由基议定书

强场绝热电离多原子自由基阳离子超快振动相干的测量

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

快速扫描电子顺磁共振打开新的途径成像生理重要参数

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