This work was supported by the Natural Science and Engineering Research Council of Canada (Discovery Grant No. 122795-2010) and the program of the Canada Research Chair in Quantum Semiconductors (JJD). The help provided by Xiaohuan Xuang, Mohamed Walid Hassen and technical assistance of Sonia Blais of the Universit&#233; de Sherbrooke Centre de caract&#233;risation de mat&#233;riaux (CCM) in collecting XPS data are greatly appreciated. NL acknowledges the Merit Scholarship Program for Foreign Student, Fonds de recherche du Qu&#233;bec - Nature et technologies, for providing a graduate student scholarship.

1.样品制备<ol><li>使用diamode划线切割的n型（P掺杂）一侧研磨Si晶片（电阻率3.1〜4.8Ω.m），其是3英寸的直径，380微米厚，成12毫米×6毫米的样品;清洁在OptiClear，丙酮和异丙醇（5分钟，每步）的样品。 </li><li>在1分钟以刻蚀掉初始氧化物的〜0.9％的HF溶液蚀刻样本;冲洗在DI水和干的高纯度（99.999％）氮（N 2）。 </li><li>在N 2袋商店准备的样品，以遏制其在空气中氧化。 </li></ol> 2.辐射能力样品的ArF（λ= 193纳米），氟化氪（λ= 248纳米）激光器。 <ol><li>在0.74毫米高腔放置样品，然后密封腔用熔融石英窗口，具有高透射紫外线（≥90％）。用H填充腔室中的0.01-0.2％的范围内，或用脱气甲基2 O 2 / H 2 O的溶液NOL使用微流体通道。 </li><li>照射与均质的ArF或KrF受激光样品以2.6和1.8的缩小，分别。通过一个圆形掩模（4毫米直径）增加激光脉冲100至600中的100个脉冲照射步骤仅2个位点上的每个样品。照射以相同的方式将样品用“枫叶”（9毫米×7.2毫米）掩模。 </li><li>在去离子水冲洗样，干与N 2冲洗;将样品在密闭容器中，然后迅速填补这个容器用 N 2中，为了事先避免暴露在空气中，以进一步的实验。 </li></ol> 3.固定化生物共轭纳米球<ol><li>稀释生物素结合和荧光素染色的40纳米直径的纳米球以pH 7.4的磷酸盐缓冲盐水（PBS，1X）溶液至10 12个粒子/ ml在室温（〜25℃）。浸泡的ArF或KrF激光器照射样品2＆＃160;小时在该溶液中于RT。 </li><li>洗涤样品，用PBS，以消除表面上的物理结合荧光素染色的纳米球。 </li></ol> 4.表面特征<ol><li>接触角（CA）的测量<ol><li>进行静态的CA测量，在室温和环境湿度的环境中的测角器。 </li><li>在微型注射器采用高纯度去离子水（电阻率17.95MΩ·厘米）;产生相似体积（〜5微升）通过降低微型注射器的类似高度对于每个测量滴在样品表面。 </li><li>捕获并保存水滴轮廓的图像由CCD摄像头，支持软件。独立测量4个不同的站点相同的照射条件。 </li><li>估计和平均从ImageJ的软件降分析模块的CA值;加载图像并将其转换为灰度;启动插件Dropsnake;放置一滴轮廓（〜10节）从左上大致几节正确的初始化蛇;接受连接这些结曲线，并按下按钮，蛇的进化曲线。注意：接触角显示的图像和表。 </li></ol></li><li> XPS测量<ol><li>调查表面化学改性与XPS光谱仪（1×10 -9托的基础压力）配备的AlKα源在150瓦工作： <ol><li>加载样品进入真空室。 </li><li>从220微米×220微米的区域收购的50 eV的通能恒定能量模式表面上的调查数据。 </li><li>从相同的分析区域获取高分辨率的扫描数据，在20电子伏特能量通过。 </li></ol></li><li>流程XPS用XPS光谱定量软件光谱数据，参考25,26。 </li></ol></li><li>荧光显微镜成像<ol><li>激发样品，这是通过“枫叶”掩模照射并暴露于荧光素染色纳米微球，用蓝光源（λ= 450〜490纳米）。 </li><li>观察荧光图像，发射在515nm处，在4X的放大荧光倒置显微镜。 </li><li>表征这些样品用原子力显微镜的表面形态，作为参考的27。 </li></ol></li></ol>

The authors have nothing to disclose.

我们提出的Si晶片的紫外激光照射的协议中的微流体腔室填充有H 2 O 2的溶液低浓度以诱导超亲水Si表面，这主要是由于的Si-OH的生成。的H 2 O 2的紫外激光光解被认为以形成负电荷的OH -基团。另外，紫外激光光电效应导致带正电的表面37的形成。因此，这些负OH的相互作用-自由基与带正电的表面导致的Si-OH的生成的表面上。所以，我们可以增?...

显着的电子和化学性能以及它的高机械强度作出硅（Si）为微电子器件和生物医学芯片1的理想选择。在Si表面的选择区域控制已收到显著关注涉及微流体和实验室片上的设备2,3。这通常是获得或者由表面粗糙度的纳米级修饰或通过在表面4的化学处理的应用程序。的表面粗糙化或图案化，以产生在Si表面上无序或有序的表面结构包括光刻法5，离子束光刻6和激光技术7。与这些方法相比，激光表面纹理化工艺被报道是较不复杂的带，以产生微结构以高空间分辨率8的潜力。然而，由于Si具有升高的纹理阈值，要求照射脉冲能量密度，以导致表面纹理超过了其烧蚀阈值（〜500毫焦耳/ 平方厘米）9，硅表面的纹理经常被协助通过采用活性气体环境，如高压六氟化硫环境4,7,8的。因此，要修改的Si表面的润湿性，许多工作已通过沉积有机10和无机膜2，或使用等离子体或电子束的表面处理11,12集中在化学处理。人们认识Si的亲水性从单数和关联的OH基团在其表面上的存在始发可以通过煮沸它在100℃的H 2 O的2溶液数分钟13来实现。然而，所述疏水硅表面状态，其中大部分是由于的Si-H或Si-O-CH 3基团的存在，可以通过湿法化学处理包括用HF酸溶液或涂布有光致抗蚀剂13的蚀刻来实现-15。为了实现硅的润湿性的选择区域的控制，通常需要复杂的构图步骤，其中包括处理化学溶液16。的紫外激光辐射的高化学反应性也被用来选择性区域处理有机膜涂覆固体基材和修改他们的润湿性17。然而，有限的数据量可在Si润湿性通过浸渍在不同的化学溶液的样品照射激光辅助修改。 在我们以前的研究中，第III-V族半导体中的空气18-20和NH 3 21紫外激光照射被成功用于改变砷化镓，砷化铟镓和InP的表面化学组成。我们建立了第III-V族半导体，紫外线激光照射在去离子（DI）水减少表面氧化物和碳化物，而吸附在半导体表面上的水增加了22。一个强疏水性的硅表面（CA〜103°），通过硅样品的ArF激光器照射获得在甲醇中的最近的工作23。如图中箭头X射线光电子能谱（XPS），这主要是由于在ArF激光器的至photodissociate CH 3 OH的能力。我们也使用的KrF或ArF激光照射的Si（001） 在 H 2 O 2在去离子水中的0.01％。这使我们能够实现选择性区域形成的Si超亲水表面（001）的特征在于邻近15°的CA。该XPS结果表明，这是由于产生的的Si-OH键上的照射表面24。 这种新技术的使用的KrF或ArF激光选择性区 Si表面的亲水/疏水表面原位改性的H 2 O 2 / H 2 O和甲醇溶液浓度低的详细说明证明这篇文章。这里提供的细节应该足够让类似的实验，由感兴趣的研究人员进行。

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>fluorescein stained nanospheres</td>
			<td>Invitrogen</td>
			<td>F8795</td>
			<td></td>
		</tr>
		<tr>
			<td>OptiClear</td>
			<td>National Diagnostics</td>
			<td>OE-101</td>
			<td></td>
		</tr>
		<tr>
			<td>ArF laser (&#955;=193 nm)</td>
			<td>Lumonics</td>
			<td>pulse master 800</td>
			<td></td>
		</tr>
		<tr>
			<td>KrF laser (&#955;=248 nm)</td>
			<td>Lumonics</td>
			<td>pulse master 800</td>
			<td></td>
		</tr>
		<tr>
			<td>XPS</td>
			<td>Kratos Analytical</td>
			<td>AXIS Ultra DLD</td>
			<td></td>
		</tr>
		<tr>
			<td>Fluorescence microscope</td>
			<td>Olympus</td>
			<td>IX71</td>
			<td></td>
		</tr>
		<tr>
			<td>XPS quantitification software</td>
			<td>CasaXPS</td>
			<td>2.3.15</td>
			<td></td>
		</tr>
	</tbody>
</table>

selective area modification of silicon surface wettability by pulsed uv laser irradiation in liquid environment

硅的可润湿性（Si）为在该材料的生物传感装置的制造和表面官能化的技术的重要参数之一。我们报告使用的KrF或ArF激光照射沉浸在与脉冲数低的液体环境中的Si（001）样品，并运行在适度低脉冲能量密度诱导硅润湿性修改的协议。晶圆浸泡长达4小时的0.01％H 2 O 2 / H 2 O解决方案并没有表现出他们的初始接触角（CA）〜75°可衡量的变化。然而，这样的晶片在一个微室500脉冲的KrF或ArF激光照射填充有0.01％ 的 H 2 O 2 / H 2 O的溶液，在250和65毫焦耳/厘米2，分别下降CA以接近15°，表示超亲水表面的形成。 OH-为端的Si（001），形成与晶片的表面形貌的任何可测量的变化，具有已证实通过X射线光电子能谱法和原子力显微镜测量。选择性区域照射样品然后浸入生物素缀合的荧光素染色的纳米球的溶液2小时，从而在非照射区域中的纳米球的一个成功的固定。这说明该方法用于选择性区域biofunctionalization和先进的基于Si的生物传感结构制造的潜力。我们还描述了使用ArF激光器晶片浸渍在甲醇（CH 3 OH）的照射的类似协议在65毫焦耳的脉冲能量密度运行/厘米2和就地形成的Si（001）的强疏水性表面具有103在CA度。该XPS结果表明ArF激光器诱导形成Si-所示的（OCH 3）λ化合物负责观察到的疏水性。但是，没有这样的化合物被发现通过XPS在Si表面上由KrF激光器在甲醇照射，展示出的KrF激光器的无能photodissociate甲醇和创建-OCH 3基团。

这些代表性的成果已经呈现在我们以前发表的作品23,24。 图1显示的网站的CA与N（脉冲数）的DI照射KrF激光器在250毫焦耳/ 平方厘米H 2 O的不同浓度h的2 O 2 / H 2 O的溶液（例如，0.01，0.02，0.05和0.2％）。随着脉冲数的所有的 H 2 O 2的溶液在CA减小。最小的CA（〜15°）为0.02和0.01％的H 2 O 2的溶液中，在500个脉冲获得。一...

Watch this Scientific Journal Video about Selective Area Modification of Silicon Surface Wettability by Pulsed UV Laser Irradiation in Liquid Environment at JoVE.com

Selective Area Modification of Silicon Surface Wettability by Pulsed UV Laser Irradiation in Liquid Environment

我们对在HF原位改变处理的Si（001）面成亲水或疏水状态通过照射在微流体室中填充用H 2 O 2 / H 2 O的溶液（0.01％-0.5％）或甲醇溶液样品的处理报告使用相对低的脉冲能量密度的脉冲UV激光。

硅表面润湿性的选择区域改性脉冲紫外激光照射在液体环境

The wettability of silicon (Si) is one of the important parameters in the technology of surface functionalization of this material and fabrication of ...

selective-area-modification-silicon-surface-wettability-pulsed-uv

Research

JoVE Journal

Engineering

8.2K 次观看.  Université de Sherbrooke. 我们对在HF原位改变处理的Si（001）面成亲水或疏水状态通过照射在微流体室中填充用H 2 O 2 / H 2 O的溶液（0.01％-0.5％）或甲醇溶液样品的处理报告使用相对低的脉冲能量密度的脉冲UV激光。 

视频: Selective Area Modification of Silicon Surface Wettability by Pulsed UV Laser Irradiation in Liquid Environment

Investigation of Early Plasma Evolution Induced by Ultrashort Laser Pulses

Early plasma is generated owing to high intensity laser irradiation of target and the subsequent target material ionization. Its dynamics plays a significant role in laser-material interaction, especially in the air environment1-11.
Early plasma evolution has been captured through pump-probe shadowgraphy1-3 and interferometry1,4-7. However, the studied time frames and applied laser parameter ranges are limited. For example, direct examinations of plasma front locations and electron number densities within a delay time of 100 picosecond (ps) with respect to the laser pulse peak are still very few, especially for the ultrashort pulse of a duration around 100 femtosecond (fs) and a low power density around 1014 W/cm2. Early plasma generated under these conditions has only been captured recently with high temporal and spatial resolutions12. The detailed setup strategy and procedures of this high precision measurement will be illustrated in this paper. The rationale of the measurement is optical pump-probe shadowgraphy: one ultrashort laser pulse is split to a pump pulse and a probe pulse, while the delay time between them can be adjusted by changing their beam path lengths. The pump pulse ablates the target and generates the early plasma, and the probe pulse propagates through the plasma region and detects the non-uniformity of electron number density. In addition, animations are generated using the calculated results from the simulation model of Ref. 12 to illustrate the plasma formation and evolution with a very high resolution (0.04 ~ 1 ps).
Both the experimental method and the simulation method can be applied to a broad range of time frames and laser parameters. These methods can be used to examine the early plasma generated not only from metals, but also from semiconductors and insulators.

An experimental method to examine the early plasma evolution induced by ultrashort laser pulses is described. Using this method, high quality images of early plasma are obtained with high temporal and spatial resolutions. A novel integrated atomistic model is used to simulate and explain the mechanisms of early plasma.

超短激光脉冲诱导的等离子体演化早期的调查

Early plasma is generated owing to high intensity laser irradiation of target and the subsequent target material ionization. Its dynamics plays a ...

科研

工程学

Characterization of Surface Modifications by White Light Interferometry: Applications in Ion Sputtering, Laser Ablation, and Tribology Experiments

In materials science and engineering it is often necessary to obtain quantitative measurements of surface topography with micrometer lateral resolution. From the measured surface, 3D topographic maps can be subsequently analyzed using a variety of software packages to extract the information that is needed.
In this article we describe how white light interferometry, and optical profilometry (OP) in general, combined with generic surface analysis software, can be used for materials science and engineering tasks. In this article, a number of applications of white light interferometry for investigation of surface modifications in mass spectrometry, and wear phenomena in tribology and lubrication are demonstrated. We characterize the products of the interaction of semiconductors and metals with energetic ions (sputtering), and laser irradiation (ablation), as well as ex situ measurements of wear of tribological test specimens.
Specifically, we will discuss:
<ol class="lroman">
	<li>Aspects of traditional ion sputtering-based mass spectrometry such as sputtering rates/yields measurements on Si and Cu and subsequent time-to-depth conversion.</li>
	<li>Results of quantitative characterization of the interaction of femtosecond laser irradiation with a semiconductor surface. These results are important for applications such as ablation mass spectrometry, where the quantities of evaporated material can be studied and controlled via pulse duration and energy per pulse. Thus, by determining the crater geometry one can define depth and lateral resolution versus experimental setup conditions.</li>
	<li>Measurements of surface roughness parameters in two dimensions, and quantitative measurements of the surface wear that occur as a result of friction and wear tests.</li>
</ol>
Some inherent drawbacks, possible artifacts, and uncertainty assessments of the white light interferometry approach will be discussed and explained.

White light microscope interferometry is an optical, noncontact and quick method for measuring the topography of surfaces. It is shown how the method can be applied toward mechanical wear analysis, where wear scars on tribological test samples are analyzed; and in materials science to determine ion beam sputtering or laser ablation volumes and depths.

白光干涉表面改性中的应用离子溅射，激光烧蚀，与摩擦学实验表征

In materials science and engineering it is often necessary to obtain quantitative measurements of surface topography with micrometer lateral resolution. ...

Fabrication of Nano-engineered Transparent Conducting Oxides by Pulsed Laser Deposition

Nanosecond Pulsed Laser Deposition (PLD) in the presence of a background gas allows the deposition of metal oxides with tunable morphology, structure, density and stoichiometry by a proper control of the plasma plume expansion dynamics. Such versatility can be exploited to produce nanostructured films from compact and dense to nanoporous characterized by a hierarchical assembly of nano-sized clusters. In particular we describe the detailed methodology to fabricate two types of Al-doped ZnO (AZO) films as transparent electrodes in photovoltaic devices: 1) at low O2 pressure, compact films with electrical conductivity and optical transparency close to the state of the art transparent conducting oxides (TCO) can be deposited at room temperature, to be compatible with thermally sensitive materials such as polymers used in organic photovoltaics (OPVs); 2) highly light scattering hierarchical structures resembling a forest of nano-trees are produced at higher pressures. Such structures show high Haze factor (&gt;80%) and may be exploited to enhance the light trapping capability. The method here described for AZO films can be applied to other metal oxides relevant for technological applications such as TiO2, Al2O3, WO3 and Ag4O4.

We describe the experimental method to deposit nanostructured oxide thin films by nanosecond Pulsed Laser Deposition (PLD) in the presence of a background gas. By using this method Al-doped ZnO (AZO) films, from compact to hierarchically structured as nano-tree forests, can be deposited.

制备纳米设计的脉冲激光沉积透明导电氧化物

Nanosecond Pulsed  Laser Deposition (PLD) in the presence of a background gas allows the deposition  of metal oxides with tunable morphology, structure, ...

Visualization of High Speed Liquid Jet Impaction on a Moving Surface

Two apparatuses for examining liquid jet impingement on a high-speed moving surface are described: an air cannon device (for examining surface speeds between 0 and 25 m/sec) and a spinning disk device (for examining surface speeds between 15 and 100 m/sec). The air cannon linear traverse is a pneumatic energy-powered system that is designed to accelerate a metal rail surface mounted on top of a wooden projectile. A pressurized cylinder fitted with a solenoid valve rapidly releases pressurized air into the barrel, forcing the projectile down the cannon barrel. The projectile travels beneath a spray nozzle, which impinges a liquid jet onto its metal upper surface, and the projectile then hits a stopping mechanism. A camera records the jet impingement, and a pressure transducer records the spray nozzle backpressure. The spinning disk set-up consists of a steel disk that reaches speeds of 500 to 3,000 rpm via a variable frequency drive (VFD) motor. A spray system similar to that of the air cannon generates a liquid jet that impinges onto the spinning disc, and cameras placed at several optical access points record the jet impingement. Video recordings of jet impingement processes are recorded and examined to determine whether the outcome of impingement is splash, splatter, or deposition. The apparatuses are the first that involve the high speed impingement of low-Reynolds-number liquid jets on high speed moving surfaces. In addition to its rail industry applications, the described technique may be used for technical and industrial purposes such as steelmaking and may be relevant to high-speed 3D printing.

Two experimental devices for examining liquid jet impingement on a high-speed moving surface are described: an air cannon device and a spinning disk device. The apparatuses are used to determine optimal approaches to the application of liquid friction modifier (LFM) onto rail tracks for top-of-rail friction control.

高速喷液嵌塞对移动表面的可视化

Two apparatuses for examining liquid jet impingement on a high-speed moving surface are described: an air cannon device (for examining surface speeds ...

Integration of Light Trapping Silver Nanostructures in Hydrogenated Microcrystalline Silicon Solar Cells by Transfer Printing

One of the potential applications of metal nanostructures is light trapping in solar cells, where unique optical properties of nanosized metals, commonly known as plasmonic effects, play an important role. Research in this field has, however, been impeded owing to the difficulty of fabricating devices containing the desired functional metal nanostructures. In order to provide a viable strategy to this issue, we herein show a transfer printing-based approach that allows the quick and low-cost integration of designed metal nanostructures with a variety of device architectures, including solar cells. Nanopillar poly(dimethylsiloxane) (PDMS) stamps were fabricated from a commercially available nanohole plastic film as a master mold. On this nanopatterned PDMS stamps, Ag films were deposited, which were then transfer-printed onto block copolymer (binding layer)-coated hydrogenated microcrystalline Si (&#181;c-Si:H) surface to afford ordered Ag nanodisk structures. It was confirmed that the resulting Ag nanodisk-incorporated &#181;c-Si:H solar cells show higher performances compared to a cell without the transfer-printed Ag nanodisks, thanks to plasmonic light trapping effect derived from the Ag nanodisks. Because of the simplicity and versatility, further device application would also be feasible thorough this approach.

A viable transfer printing-based methodology to introduce plasmonic metal nanostructures in solar cells is described. Using nanopillar poly(dimethylsiloxane) stamps, an Ag-based ordered nanodisk array was integrated with standard hydrogenated microcrystalline Si solar cells, which led to improved device performances due to plasmonic light trapping.

灯光诱杀银纳米结构通过转移印花在氢化微晶硅太阳能电池集成

One of the potential applications of metal nanostructures is light trapping in solar cells, where unique optical properties of nanosized metals, commonly ...

Automation of Mode Locking in a Nonlinear Polarization Rotation Fiber Laser through Output Polarization Measurements

When a laser is mode-locked, it emits a train of ultra-short pulses at a repetition rate determined by the laser cavity length. This article outlines a new and inexpensive procedure to force mode locking in a pre-adjusted nonlinear polarization rotation fiber laser. This procedure is based on the detection of a sudden change in the output polarization state when mode locking occurs. This change is used to command the alignment of the intra-cavity polarization controller in order to find mode-locking conditions. More specifically, the value of the first Stokes parameter varies when the angle of the polarization controller is swept and, moreover, it undergoes an abrupt variation when the laser enters the mode-locked state. Monitoring this abrupt variation provides a practical easy-to-detect signal that can be used to command the alignment of the polarization controller and drive the laser towards mode locking. This monitoring is achieved by feeding a small portion of the signal to a polarization analyzer measuring the first Stokes parameter. A sudden change in the read out of this parameter from the analyzer will occur when the laser enters the mode-locked state. At this moment, the required angle of the polarization controller is kept fixed. The alignment is completed. This procedure provides an alternate way to existing automating procedures that use equipment such as an optical spectrum analyzer, an RF spectrum analyzer, a photodiode connected to an electronic pulse-counter or a nonlinear detecting scheme based on two-photon absorption or second harmonic generation. It is suitable for lasers mode locked by nonlinear polarization rotation. It is relatively easy to implement, it requires inexpensive means, especially at a wavelength of 1550 nm, and it lowers the production and operation costs incurred in comparison to the above-mentioned techniques.

A protocol to detect and automate mode locking in a pre-adjusted nonlinear polarization rotation fiber laser is presented. The detection of a sudden change in the output polarization state when mode locking occurs is used to command the alignment of an intra-cavity polarization controller in order to find mode-locking conditions.

锁模自动化的非线性偏振旋转光纤激光器通过输出偏振测量

When a laser is mode-locked, it emits a train of ultra-short pulses at a repetition rate determined by the laser cavity length. This article outlines a ...

Emission Spectroscopic Boundary Layer Investigation during Ablative Material Testing in Plasmatron

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

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

烧蚀材料在试验过程中等离子体发生器发射光谱边界层研究

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

High Temperature Fabrication of Nanostructured Yttria-Stabilized-Zirconia (YSZ) Scaffolds by In Situ Carbon Templating Xerogels

We demonstrate a method for the high temperature fabrication of porous, nanostructured yttria-stabilized-zirconia (YSZ, 8 mol% yttria - 92 mol% zirconia) scaffolds with tunable specific surface areas up to 80 m2&#183;g-1. An aqueous solution of a zirconium salt, yttrium salt, and glucose is mixed with propylene oxide (PO) to form a gel. The gel is dried under ambient conditions to form a xerogel. The xerogel is pressed into pellets and then sintered in an argon atmosphere. During sintering, a YSZ ceramic phase forms and the organic components decompose, leaving behind amorphous carbon. The carbon formed in situ serves as a hard template, preserving a high surface area YSZ nanomorphology at sintering temperature. The carbon is subsequently removed by oxidation in air at low temperature, resulting in a porous, nanostructured YSZ scaffold. The concentration of the carbon template and the final scaffold surface area can be systematically tuned by varying the glucose concentration in the gel synthesis. The carbon template concentration was quantified using thermogravimetric analysis (TGA), the surface area and pore size distribution was determined by physical adsorption measurements, and the morphology was characterized using scanning electron microscopy (SEM). Phase purity and crystallite size was determined using X-ray diffraction (XRD). This fabrication approach provides a novel, flexible platform for realizing unprecedented scaffold surface areas and nanomorphologies for ceramic-based electrochemical energy conversion applications, e.g. solid oxide fuel cell (SOFC) electrodes.

High Temperature Fabrication of Nanostructured Yttria-Stabilized-Zirconia YSZ Scaffolds by In Situ Carbon Templating Xerogels

A protocol for fabricating porous, nanostructured yttria-stabilized-zirconia (YSZ) scaffolds at temperatures between 1,000 &#176;C and 1,400 &#176;C is presented.

通过纳米氧化钇稳定的二氧化锆（YSZ）的支架的高温加工<em&gt;原位</em&gt;碳模板干凝胶

We demonstrate a method for the high temperature fabrication of porous, nanostructured yttria-stabilized-zirconia (YSZ, 8 mol% yttria - 92 mol% zirconia) ...

Preparation of Liquid Crystal Networks for Macroscopic Oscillatory Motion Induced by Light

A strategy based on doped liquid crystalline networks is described to create mechanical self-sustained oscillations of plastic films under continuous light irradiation. The photo-excitation of dopants that can quickly dissipate light into heat, coupled with anisotropic thermal expansion and self-shadowing of the film, gives rise to the self-sustained deformation. The oscillations observed are influenced by the dimensions and the modulus of the film, and by the directionality and intensity of the light. The system developed offers applications in energy conversion and harvesting for soft-robotics and automated systems.
The general method described here consists of creating free-standing liquid crystalline films and characterizing the mechanical and thermal effects observed. The molecular alignment is achieved using alignment layers (rubbed polyimide), commonly used in the display manufacturing industry. To obtain actuators with large deformation, the mesogens are aligned and polymerized in a splay/bend configuration, i.e., with the director of the liquid crystals (LCs) going gradually from planar to homeotropic through the film thickness. Upon irradiation, the mechanical and thermal oscillations obtained are monitored with a high-speed camera. The results are further quantified by image analysis using an image processing program.

The goal of the protocol is to create liquid crystalline polymer films that can mechanically oscillate under continuous light irradiation. We describe in great detail the conception of free-standing films, from the liquid crystal alignment method to the photo-actuation. The experimental protocol applied to prepare this material is broadly applicable.

光诱导的宏观振荡运动液晶网络的制备

A strategy based on doped liquid crystalline networks is described to create mechanical self-sustained oscillations of plastic films under continuous ...

Quantitative Analysis of Vacuum Induction Melting by Laser-induced Breakdown Spectroscopy

Vacuum induction melting is a popular method for refining high purity metal and alloys. Traditionally, standard process control in metallurgy involves several steps, include drawing samples, cooling, cutting, transport to the laboratory, and analysis. The whole analysis process requires more than 30 minutes, which hinders on-line process control. Laser-induced breakdown spectroscopy is an excellent on-line analysis method that can satisfy the requirements of vacuum induction melting because it is fast and noncontact and does not require sample preparation. The experimental facility uses a lamp-pumped Q-switched laser to ablate melted liquid steel with an output energy of 80 mJ, a frequency of 5 Hz, a FWHM pulse width of 20 ns, and a working wavelength of 1,064 nm. A multi-channel linear charge coupled device (CCD) spectrometer is used to measure the emission spectrum in real time, with a spectral range from 190 to 600 nm and a resolution of 0.06 nm at a wavelength of 200 nm. The protocol includes several steps: standard alloy sample preparation and an ingredient test, smelting of standard samples and determination of the laser breakdown spectrum, and construction of the elements concentration quantitative analysis curve of each element. To realize the concentration analysis of unknown samples, the spectrum of a sample also needs to be measured and disposed with the same process. The composition of all main elements in the melted alloy can be quantitatively analyzed with an internal standard method. The calibration curve shows that the limit of detection of most metal elements ranges from 20-250 ppm. The concentration of elements, such as Ti, Mo, Nb, V, and Cu, can be lower than 100 ppm, and the concentrations of Cr, Al, Co, Fe, Mn, C, and Si range from 100-200 ppm. The R2 of some calibration curves can exceed 0.94.

During vacuum induction melting, laser-induced breakdown spectroscopy is used to perform real-time quantitative analysis of the main-ingredient elements of a molten alloy.

激光击穿光谱对真空感应熔融的定量分析

Vacuum induction melting is a popular method for refining high purity metal and alloys. Traditionally, standard process control in metallurgy involves ...