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.サンプル調製<ol><li> （Pドープ）は、n型を切断するdiamodeスクライブを使用して12ミリメートルのx 6mmのサンプルに、直径3インチ、380ミクロンの厚さである片面研磨Siウエハ（抵抗率3.1〜4.8Ω.m）。 OptiClear、アセトン、イソプロピルアルコール（すべてのステップのために、5分）でサンプルを清掃してください。 </li><li> 1分の初期酸化物をエッチングするため〜0.9％のHF溶液中でエッチングサンプル。 DI水ですすぎ、高純度（99.999％）、窒素（N 2）で乾燥しました。 </li><li>ストアは、空気中のそれらの酸化を抑制するために、N 2袋でサンプルを用意しました。 </li></ol> ArF（λ= 193 nm）をのKrF（λ= 248 nm）のレーザー2.照射サンプル。 <ol><li>場所サンプル0.74ミリメートル背の高い室内で、その後は、UVの高い伝送（≥90％）を持つ溶融シリカ窓で室内を密閉。 0.01から0.2％の範囲内、または脱気メタでH 2 O 2 / H 2 O溶液でチャンバーを満たしますマイクロ流体チャネルを使用してNOL。 </li><li>それぞれ、2.6および1.8の縮小で均質化したArF用、KrFレーザーでサンプルを照射します。円形マスク（直径4mm）を介して100パルスのステップ100から600へのレーザパルスを増加させることによって、各サンプルにのみ2つの部位を照射します。 「メープルリーフ」（9ミリメートル×7.2ミリメートル）のマスクと同じ方法でサンプルを照射します。 </li><li> N 2フラッシュで乾燥DI水ですすぎ、サンプル、。その後すぐに、さらなる実験の前に、空気への暴露を避けるために、N 2を用いてこの容器を充填し、密封容器に試料を置き。 </li></ol> 3の固定化バイオコンジュゲートナノスフィア<ol><li> pH7.4のリン酸緩衝生理食塩水（PBS、1X）を室温で10 12粒子/ mlの溶液中のビオチン結合およびフルオレセイン染色された40 nmの直径のナノ粒子を希釈（〜25℃）。 2のためのArF用、KrFレーザー照射サンプルを浸し＆＃160; RTでこの溶液中の時間。 </li><li> PBSで洗浄サンプルは、表面に物理的に結合フルオレセイン染色ナノスフェアを排除します。 </li></ol> 4.表面キャラクタリゼーション<ol><li>接触角（CA）の測定<ol><li> RTと周囲の湿度の環境下でのゴニオメータで静的なCAの測定を行います。 </li><li>マイクロシリンジで、高純度の脱イオン水（比抵抗17.95MΩ・cm程度）を用います。同様の体積（〜5μL）は、すべての測定のために同様の高さをマイクロシリンジを低下させることにより試料表面に降下発生します。 </li><li>水はソフトウェアとCCDカメラでプロフィール画像をドロップキャプチャして保存します。同じ照射条件で独立して4つの異なる部位を測定します。 </li><li>見積もりとImageJソフトウェアからドロップ解析モジュール内のCA値を平均。画像をロードし、グレースケールにそれを変更します。プラグインDropsnakeを起動します。左からドロップ輪郭（〜10ノット）でのおおよその数ノットを配置右の蛇を初期化します。これらの結び目を結ぶ曲線を受け入れ、ヘビボタンを押してカーブを進化させます。注意：接触角は、画像や表で表示されます。 </li></ol></li><li> XPS測定<ol><li> 150 Wで働くアルKα源を装備したXPS分光計（1×10 -9トルのベース圧力）で表面化学修飾を調査： <ol><li>真空チャンバ内にサンプルをロードします。 </li><li> 220ミクロン×220ミクロンの領域から50 eVのパスエネルギーの一定のエネルギーモードにおける表面調査データを取得します。 </li><li> 20 eVのエネルギーを渡すのと同じ分析領域から高解像度のスキャンデータを取得します。 </li></ol></li><li> 25,26を参照されるプロセスは、XPSスペクトルの定量化ソフトウェアでスペクトルデータをXPS。 </li></ol></li><li>蛍光顕微鏡イメージング<ol><li>使用して、「メープルリーフ」マスクを介して照射し、染色されたナノスフェアをフルオレセインに曝露されたサンプルを、エキサイト青色光源（λ= 450〜490 nm）で。 </li><li> 4Xの倍率で蛍光倒立顕微鏡を用いて、515 nmで発光する、蛍光画像を観察します。 </li><li>参照27のように、AFMを用いてこれらの試料の表面形態を特徴づけます。 </li></ol></li></ol>

The authors have nothing to disclose.

我々が原因のSi-OHの生成に主に超親水Si表面を誘発するためにH 2 O 2溶液の低濃度で満たされたマイクロ流体チャンバ内のSiウエハのUVレーザー照射プロトコルを提案しています。ラジカル- H 2 O 2のUVレーザー光分解は負に帯電し、OHを形成することになりました。また、UVレーザー光電効果は、正に帯電した表面37が形成されます。従って、これらの負の?...

注目すべき電子的および化学的性質だけでなく、その高い機械的強度は、シリコン（Si）のマイクロエレクトロニクスデバイスおよび生物医学チップ1のための理想的な選択をしました。 Si表面の選択領域の制御は、マイクロ流体を含む用途およびラボオンチップデバイス2,3 .Thisために大きな注目を受 ​​けているが、多くの場合、表面粗さのナノスケールの修飾により又は表面4の化学処理のいずれかによって得られます。 Si表面に不規則又は規則の表面構造を生成するために粗面化またはパターニングは、フォトリソグラフィ5、イオンビームリソグラフィー6及びレーザ技術7を含みます 。これらの方法に比べて、レーザ表面テクスチャリング工程は、高空間分解能8に微細構造を生成する可能性を有するより複雑であると報告されています。しかし、Siはにパルスフルエンスの照射を必要とする、上昇テクスチャリングのしきい値を持っているとして、そのアブレーション閾値（〜500ミリジュール/ cm 2）で9を超える表面テクスチャリングを誘発し、Si表面のテクスチャリングは、しばしば、このような高圧SF 6環境4,7,8のものと反応性ガス雰囲気を使用することによって支援されています。これにより、Si表面の濡れ性を改変するために、多数の作品は10有機および無機膜2を堆積し 、プラズマまたは電子ビーム表面処理11,12を使用して、化学的処理に焦点を当てています。これは、その表面に単数および関連するOH基の存在に由来するシリコンの親水性は、数分13 100℃でH 2 O 2溶液中で煮沸することによって達成され得ることが認識されます。ただし、のSi-H又はSi-O-CH 3基の存在に起因している大部分の疎水性のSi表面の状態は、フォトレジスト13を HF酸溶液またはコーティングをエッチング含む湿式化学処理によって達成することができます-15。 Siとの濡れ性の選択領域の制御を達成するために、複雑なパターニング工程は、通常、薬液16中に治療を含む、必要とされます。 UVレーザー放射の高い化学反応性はまた、選択領域プロセス有機膜コーティングされた固体支持体に使用され、それらの湿潤性17を変更されています。しかし、限られた量のデータは、異なる化学溶液に浸漬した試料の照射によるSiの濡れ性のレーザーアシスト修正で提供されています。 我々の以前の研究では、空気18-20及びNH 3 21におけるIII-V半導体のUVレーザー照射が正常のGaAs、InGaAsのとInPの表面の化学組成を変更するために使用しました。半導体表面に吸着した水22を上昇させる一方で、我々は、脱イオン中III-V半導体のUVレーザー照射を確立し（DI）水は、表面酸化物および炭化物を減少させます。強い疎水性Si表面（CA〜103°）が我々の最近の研究23で、メタノール中のSiサンプルのArFレーザを照射して得ました。 X線光電子分光法（XPS）によって示されるように、これは、主にCH 3 OHをphotodissociateするArFレーザの能力です。我々はまた、DI水中のH 2 O 2を0.01％に（001）シリコンを照射するのKrFや、ArFレーザを使用しました。これは、私たちは近くに15°のCAによって特徴づけたSiの超親水性表面（001）の選択領域の形成を達成することができました。 XPSの結果は、この照射面24上のSi-OH結合の生成によるものであることを示唆しています。 H 2 O 2 / H 2 Oおよびメタノール溶液の低濃度のSi表面の親水性/疎水性表面のその場での変更で選択領域のためのKrFやArFレジストレーザーを使用して、この新しい技術の詳細については、この記事で示されています。ここで提供される詳細が十分でなければなりません同様の実験は、関心のある研究者によって実行されることを可能にします。

<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

シリコンの濡れ性（Si）は、表面、この材料の機能化及びバイオセンシングデバイスの製造の技術における重要なパラメータの一つです。我々は、Siの濡れ性の変更を誘導するために適度に低いパルスフルエンスのパルス数が少ない液体環境中に浸漬したSi（001）のサンプルを照射のKrFやArFレジストレーザを用いて動作のプロトコルに報告します。ウエハは、彼らの初期の接触角（CA）〜75°の測定可能な変化を示さなかった0.01％のH 2 O 2 / H 2 O溶液中で最大4時間浸漬しました。しかし、500パルスのKrFと250と65ミリジュール/ cm 2で0.01％のH 2 O 2 / H 2 O溶液で満たされたマイクロチャンバー内のようなウェーハのArFレジストのレーザー照射は、それぞれ、近い15°にCAを減少しています超親水性表面の形成を示します。ウェハの表面形態の無い測定可能な変化とOH-終端Si（001）の形成は、持っていますX線光電子分光法及び原子間力顕微鏡測定によって確認されました。選択領域に照射サンプルは、非照射領域におけるナノスフェアの成功固定化の結果、2時間、ビオチン結合フルオレセイン染色ナノスフィア溶液に浸漬しました。これは高度なSi系バイオセンシング・アーキテクチャの選択領域の生体機能化および製造のための方法の可能性を示しています。また、65ミリジュールのパルスフルエンスで動作するArFレーザを用いて、メタノール（CH 3 OH）に浸漬ウエハの照射の同様のプロトコルを記述/ cm 2であり、103のCAを有するSi（001）の強い疎水性表面のその場形成の °。 XPSの結果は、Si-でのArFレーザ誘起される形成の観察された疎水性のために（OCH 3）Xの化合物責任を示しています。しかしながら、そのような化合物を実証し、メタノール中でKrFレーザーにより照射したSi表面上のXPSによって検出されませんでしたKrFレーザのできないことは、メタノールをphotodissociateと-OCH 3ラジカルを作成します。

これらの代表的な結果は、我々の以前発表された研究23,24で提示されている。 図1を H、異なる濃度のためのDI H 2 Oで250ミリジュール/ cm 2のKrFレーザーによって照射サイト上のN対CA（パルス数）を示しています2 O 2 / H 2 O 溶液 （例えば、0.01、0.02、0.05および0.2％）。 CAは、すべてのH 2 O 2溶液のためのパルス数の増加に...

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

我々は、H 2 O 2 / H 2 O溶液（0.01％-0.5％）またはメタノール溶液で満たされたマイクロ流体チャンバ内でサンプルを照射することにより、親水性又は疎水性の状態にするのSi（001）表面を処理されたHF の現場変更でのプロセスについて報告相対的な低パルスフルエンスのパルスUVレーザーを使用して。

液体環境におけるパルスUVレーザー照射によるシリコン表面の濡れ性の選択エリア変更

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 ビュー.  Université de Sherbrooke. 我々は、H 2 O 2 / H 2 O溶液（0.01％-0.5％）またはメタノール溶液で満たされたマイクロ流体チャンバ内でサンプルを照射することにより、親水性又は疎水性の状態にするのSi（001）表面を処理されたHF の現場変更でのプロセスについて報告相対的な低パルスフルエンスのパルスUVレーザーを使用して。 

ビデオ: 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.

超短レーザーパルスにより誘起された初期プラズマの進化の解明

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

工学

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.

白色光干渉法による表面改質のキャラクタリゼーション：イオンスパッタリング、レーザーアブレーション法、およびトライボロジー実験における応用

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.

パルスレーザー蒸着法によるナノエンジニアリング透明導電性酸化物の作製

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.

表面移動に高速液体ジェット宿便の可視化

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.

転写印刷により水素化微結晶シリコン太陽電池の光トラッピング銀ナノ構造の統合

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.

出力偏光測定を通じて非線形偏波回転ファイバレーザにおけるモードロックの自動化

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.

プラズマトロン内のアブレーション材料試験中の放射分光境界層調査

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.

によってナノ構造イットリア安定化ジルコニア（YSZ）足場の高温製作<em&gt;その場での</em&gt;カーボンテンプレート化キセロゲル

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.

巨視的揺動運動の光によって誘起される液晶ネットワークの準備

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.

レーザー誘起分解分光法による真空誘導融解の定量分析

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