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. 샘플 준비 <ol><li> ((P)가 도핑 된) 한 쪽은 Si 웨이퍼 연마 n 형을 절단하는 diamode 스크라이브를 사용하여 (저항을 3.1 ~ 4.8 Ω.m) 직경이 3 인치, 12mm X 6mm의 샘플로, 380 μm의 두께; OptiClear, 아세톤, 이소 프로필 알코올 (모든 단계에 대한 5 분)에서 샘플을 청소하십시오. </li><li> 1 분은 초기 산화물을 얻어 에칭 용 ~ 0.9 %의 HF 용액에서 식각 된 샘플; (N 2) DI 물에 씻어 고순도 (99.999 %) 질소 건조. </li><li> N이 가방에 보관 준비 샘플은 공기에서의 산화를 억제한다. </li></ol> 의 ArF (λ = 193 ㎚)과의 KrF (λ = 248 nm의) 레이저 2. 조사 샘플. <ol><li> 장소 0.74 mm의 높이 실에서 샘플 후 자외선에 높은 전송 (≥90 %)가 용융 실리카 창으로 챔버를 밀봉. H와 0.01~0.2 %의 범위 또는 탈기 메타 2 O 2 / H 2 O 용액 챔버를 채우기NOL 미세 유체 채널을 사용. </li><li> 각각 2.6 및 1.8의 사이즈 축소에 균질의 ArF 용, KrF 레이저를 샘플을 조사. 원형 마스크 (직경 4mm)을 통해 100 단계에서 펄스 ​​100-600 레이저 펄스를 증가시킴으로써 각각의 샘플에 불과 2 사이트를 조사. &quot;메이플 리프&quot;(9mm X 7.2 mm) 마스크와 같은 방법으로 시료를 조사한다. </li><li> N 2 세척 건조 DI 물 린스 샘플; 신속 추가 실험 전에 공기에 노출되는 것을 방지하기 위해, N (2)와이 컨테이너를 채우는, 밀폐 용기에 시료를 배치했다. </li></ol> (3)의 고정화 바이오 복합 나노 <ol><li> pH 7.4의 인산염 완충 식염수 (PBS, 1X) RT 10 12 입자 / ㎖로 용액에서 비오틴 - 컨쥬 게이트 및 형광 염색 40 nm의 직경이 나노 희석 (~ 25 ℃). 2 대한의 ArF 또는의 KrF 레이저 조사 샘플을 담가# 160; RT에서이 솔루션의 시간. </li><li> PBS로 세척 샘플 표면에 물리적으로 결합 된 형광 염색 나노를 제거합니다. </li></ol> 4. 표면 특성 <ol><li> 접촉각 (CA) 측정 <ol><li> RT 및 주위 습도의 환경에서 CA 각도계 정적 측정을 수행한다. </li><li> 마이크로 주사기 고순도 DI 물 (비저항 17.95 MΩ · cm)을 채용; 비슷한 볼륨을 생성 (~ 5 μL)은 모든 측정 비슷한 높이로 마이크로 주사기를 낮추는 방법으로 시료 표면에 삭제합니다. </li><li> 캡처 물이 소프트웨어와 CCD 카메라에 의해 프로필 이미지를 떨어 저장합니다. 같은 조사 조건과 독립적으로 4 개의 다른 사이트를 측정한다. </li><li> 추정은 ImageJ에 소프트웨어의 액적 분석 모듈에서 CA 값을 평균; 이미지를로드 및 그레이 스케일로 변경; 플러그인 Dropsnake를 시작; 왼쪽에서 드롭 윤곽 (~ 10 노트)에 대략 몇 노트를 배치바로 뱀을 초기화; 이러한 매듭 연결 곡선을 적용하고 뱀 버튼을 눌러 곡선 진화. 주 : 접촉각은 이미지와 표에 표시되어있다. </li></ol></li><li> XPS 측정 <ol><li> 150 W에서 일하고 알 Kα 소스와 복 XPS 분광계 (1 × -9 토르의 기본 압력)와 표면의 화학적 변형을 조사 : <ol><li> 진공 챔버로 샘플을 로딩. </li><li> 220 μm의 X 220 ㎛ 인 영역으로부터 50 eV의 통과 에너지가 일정 에너지 모드에서의 표면 검사 데이터를 획득. </li><li> 20 eV의 에너지 전달에서 동일한 분석 영역에서 고해상도 검사 데이터를 획득. </li></ol></li><li> 25, 26을 참조하는 바와 같이 프로세스는 XPS 스펙트럼 정량 소프트웨어와 데이터를 XPS 스펙트럼. </li></ol></li><li> 형광 현미경 이미징 <ol><li> &quot;단풍 나무 잎&quot;마스크를 통해 조사 및 스테인드 나노를 형광에 노출 된 샘플을, 흥분 사용청색 광원 (λ = 450 ~ 490 ㎚). </li><li> 4 배의 배율에서 형광 도립 현미경으로, 515 nm에서 발광, 형광 이미지를 관찰한다. </li><li> 27를 참조로, AFM으로 이들 샘플의 표면 모폴로지를 특성화. </li></ol></li></ol>

The authors have nothing to disclose.

우리 때문에 SI-OH의 발생에 주로 초 친수성 실리콘 표면을 유도하는 H 2 O 2 용액의 농도가 낮은로 채워진 미세 유체 챔버 내에 Si 웨이퍼의 UV 레이저를 조사하는 프로토콜을 제안 하였다. 라디칼 - H 2 O 2의 UV 레이저의 광분해에 부정적인 OH 충전을 형성하기로했다. 또한, UV 레이저, 광전 효과 양전하 표면 (37)의 형성을 이끈다. 따라서, 이러한 부정적?...

놀라운 전자 화학적 특성뿐만 아니라 기계적 강도는 실리콘 (Si) 마이크로 전자 장치 및 생물 의학 칩 (1)을위한 이상적인 선택을 만들었습니다. 실리콘 표면의 선택 영역의 제어는 마이크로 유체 및 랩 온어 칩 장치 2,3- .This 종종 수득하거나, 표면 거칠기의 나노 크기 변경에 의해 또는 표면 (4)의 화학 처리가되어 관련된 애플리케이션에 상당한 관심을 받고있다. 실리콘 표면 상에 정렬 된 표면 또는 무질서한 구조를 생성하기 위해 표면 거칠기 또는 패터닝은 포토 리소그래피 (5), 이온빔 리소그래피 (6) 레이저 (7) 기술을 포함한다. 이들 방법과 비교하여, 레이저 표면 텍스쳐링 공정은 높은 공간 해상도 8 마이크로 구조체를 제조 할 가능성이있는 덜 복잡한 것으로보고된다. 그러나시는 펄스 플루 언스에와 높은 텍스쳐 임계 값, 요구 조사를 가지고로그 절제 임계치 (~을 500mJ / cm 2) 9를 초과하는 표면 텍스쳐링을 유도, 실리콘 표면 텍스쳐링은 흔히 고압 SF 6 환경 4,7,8의 경우와 반응성 가스 분위기를 채용함으로써 지원되었다. 따라서, 실리콘 표면의 습윤성을 수정하려면 많은 작품 10 유기 및 무기 박막 (2)을 증착 또는 플라즈마 또는 전자빔 표면 처리 (11, 12)을 사용하여 화학 처리에 초점을 맞추고있다. 몇 분이 13 100 ℃에서 H 2 O 2 용액을 비등에 의해 달성 될 수있는 표면에 단수와 관련 OH 기의 존재로부터 유래의 Si의 친수성을 인식한다. 그러나의 Si-H 또는 Si-O-CH 3 기의 존재로 인한 대부분의 소수성 실리콘 표면 상태는, 포토 레지스트 (13)와 HF 산 용액 또는 코팅 에칭 관련된 습식 화학적 처리에 의해 달성 될 수있다-15. Si를 선택 영역의 습윤성 제어를 달성하기 위해, 복잡한 패터닝 공정은 일반적으로 약액 (16) 처리를 포함해야한다. UV 레이저 방사선의 높은 화학 반응성이 또한 선택 영역 프로세스 유기 막 코팅에 사용되는 고체 기질과 그 습윤성 17을 수정하고있다. 그러나 제한된 양의 데이터는 다른 화학 솔루션에 몰입 샘플 조사에 의한시의 습윤성의 레이저를 이용한 변형에서 사용할 수 있습니다. 이전 연구에서, 공기 18-20 및 NH 3 (21) III-V 반도체의 UV 레이저 조사가 성공적 갈륨 비소, 인듐 갈륨 비소 및 InP의 표면의 화학적 조성을 변경하는 데 사용 하였다. 반도체 표면에 흡착 된 물 (22)을 증가하면서 탈에서 III-V 반도체의 UV 레이저를 조사 설립 (DI) 물은 표면 산화물 및 탄화물을 감소시킨다. 강한 소수성 실리콘 표면 (CA ~ 103 °)의 최근의 일 (23)에 메탄올의 Si 샘플의 ArF 레이저를 조사하여 얻었다. X 선 광전자 분광법 (XPS)에 의해 지시 된 바와 같이, 이는 주로 기인 CH 3 OH를 photodissociate하기의 ArF 레이저의 능력이다. 우리는 또한 DI 물에 H 2 O 2의 0.01 %에 (001)시에 조사의 KrF과의 ArF 레이저를 사용하고 있습니다. 이것은 우리가 가까운 15 ° CA의 특징으로 초 친수성 ​​표면의 Si (001)의 선택 영역 형성을 달성 할 수 있었다. XPS 결과는이 조사면 (24)에 SI-OH 결합의 생성에 기인하는 것이 좋습니다. H 2 O 2 / H 2 O 및 메탄올 솔루션의 낮은 농도에서 실리콘 표면의 친수성 / 소수성 표면의 현장 수정에서 선택 영역의 KrF과의 ArF 레이저를 사용하여이 새로운 기술에 대한 자세한 설명은이 문서에서 설명된다. 여기에 제공된 정보는 충분합니다수 있도록 유사한 실험은 관심이 연구자에 의해 수행된다.

<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

실리콘의 젖음성 (SI)는 바이오 센싱 장치의 재료 및 제조의 표면 기능화 기술의 중요한 변수 중 하나입니다. 우리는시의 습윤성 수정을 유도하기 위해 적당히 낮은 펄스 플루 언스에서 펄스의 수가 적은 액체 환경에 침지시 (001) 샘플 조사의 KrF과의 ArF 레이저를 사용하여 작동하는 프로토콜에보고한다. 웨이퍼는 초기 접촉각 (CA) ~ 75 °에서 측정 가능한 변화를 보이지 않았다 0.01 %의 H 2 O 2 / H 2 O 용액에서 최대 4 시간 동안 침지. 그러나, microchamber 이러한 웨이퍼의 500 펄스의 KrF과의 ArF 레이저 조사가 0.01 %의 H 가득 2 2 O 용액 250 65 엠제이 / ㎠에서 각각 가까운 15 °에 CA를 감소 / H O 2, 초 친수성 ​​표면의 형성을 나타낸다. 웨이퍼의 표면 형태없이 측정 가능한 변화 OH 종료시 (001)의 형성은,이X 선 광전자 분광법 및 원자력 현미경 측정에 의해 확인되었다. 선택 영역 샘플 조사는 비 조사 영역에서 나노 구의 성공 고정화 결과 2 시간 바이오틴 - 공액 형광 염색 나노 용액에 침지 하였다. 이것은 선택 영역 biofunctionalization 고급 Si 계 바이오 센싱 구조의 제작 방법의 가능성을 예시한다. 또한 65 mJ의 펄스 플루 언스에서 동작의 ArF 레이저를 사용하여, 메탄올 (CH 3 OH)에 침지하여 웨이퍼의 조사 유사한 프로토콜을 서술 / cm 2 (103)의 CA와의 Si (001)의 강한 소수성 표면의 인 시츄 형성 °. XPS 결과의 Si-의의 ArF 레이저 유도 형성을 나타냅니다 (OCH 3) 관찰 된 소수성에 대한 X 화합물 책임. 그러나, 이러한 화합물은 보여주는 메탄올의 KrF 레이저에 의해 조사 된 Si 표면 상 XPS에 의해 발견되지의 KrF 레이저의 무능력 메탄올을 photodissociate 및 -OCH 3 라디칼을 생성 할 수 있습니다.

이러한 대표적인 결과는 그림 1. 이전 출판 일 (23, 24)에서 제시 H의 서로 다른 농도에 대한 H 2 O DI 250 엠제이 / ㎠에서의 KrF 레이저로 조사 사이트에 N (펄스 수) 대 CA를 보여주고있다 2 O 2 / H 2 O 용액 (예., 0.01, 0.02, 0.05 및 0.2 %). CA는 모두 H 2 O 2 솔루션 펄스 수를 증가와 감소한다. 0.02 및 0.01 % H 2 O 2 ?...

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

우리는 HF의 시츄 변경이 2 O 2 / H 2 O 용액 (0.01 % -0.5 %) 또는 메탄올 용액 H로 채워진 미세 유체 챔버에서 샘플을 조사함으로써 친수성 또는 소수성 상태의 Si (001) 표면 처리에서의 공정보고 상대적으로 낮은 펄스 UV 플루 언스의 레이저 펄스를 사용.

액체 환경에서의 펄스 자외선 레이저 조사에 의한 실리콘 표면의 젖음성의 선택 영역 수정

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

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Engineering

8.2K 조회수.  Université de Sherbrooke.  우리는 HF의 시츄 변경이 2 O 2 / H 2 O 용액 (0.01 % -0.5 %) 또는 메탄올 용액 H로 채워진 미세 유체 챔버에서 샘플을 조사함으로써 친수성 또는 소수성 상태의 Si (001) 표면 처리에서의 공정보고 상대적으로 낮은 펄스 UV 플루 언스의 레이저 펄스를 사용. 

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

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.

이온 스퍼터링에 응용 프로그램, 레이저 절제하고, Tribology 실험 : 화이트 빛 간섭 측정법에 의한 표면 수정의 특성

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

연구

공학

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.

의 제작 펄스 레이저 증착에 의해 투명 실시 산화물 나노 설계

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.

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.

전송 인쇄하여 수소 첨가 미세 결정 실리콘 태양 전지에 빛 트래핑 실버 나노 구조의 통합

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.

출력 편광 측정을 통해 비선형 편광 회전 광섬유 레이저의 모드 잠금의 자동화

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.

Plasmatron에서 절제 재료 시험 중에 방출 분광 경계 계층 조사

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.

에 의한 나노 구조 산화 이트륨 안정화 지르코니아 (YSZ) 비계의 고온 제작<em&gt; 시츄</em&gt; 탄소 템플릿 생성 크 세로 겔

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

Orientational Transition in a Liquid Crystal Triggered by the Thermodynamic Growth of Interfacial Wetting Sheets

In liquid crystal (LC) physical chemistry, molecules near the surface play a great role in controlling bulk orientation. Thus far, mainly to achieve desired molecular orientation states in LC displays, the "static" surface property of LCs, so-called surface anchoring, has been intensively studied. As a rule of thumb, once the initial orientation of LCs is "locked" by specific surface treatments, such as rubbing or treatment with a specific alignment layer, it hardly changes with temperature. Here, we present a system exhibiting an orientational transition upon temperature variation, which conflicts with the consensus. Right on the transition, the bulk LC molecules experience the orientational rotation, with 90&#176; between the planar (P) orientation at high temperatures and the vertical (V) orientation at low temperatures in the first-order transitional manner. We have tracked thermodynamic surface anchoring behavior by means of polarizing optical microscopy (POM), dielectric spectroscopy (DS), high-resolution differential scanning calorimetry (HR-DSC), and grazing incidence X-ray diffraction (GI-XRD) and reached a plausible physical explanation: that the transition is triggered by a growth of surface wetting sheets, which impose the V orientation locally against the P orientation in the bulk. This landscape would provide a general link explaining how the equilibrium bulk orientation is affected by surface-localized orientation in many LC systems. In our characterization, POM and DS are advantageous by offering information on the spatial distribution of the orientation of LC molecules. HR-DSC gives information about the precise thermodynamic information on transitions, which cannot be addressed by conventional DSC instruments due to limited resolution. GI-XRD provides information on surface-specific molecular orientation and short-range orderings. The goal of this paper is to present a protocol for preparing a sample that exhibits the transition and to demonstrate how the thermodynamic structural variation, both in the bulk and on surfaces, can be analyzed through the abovementioned methods.

Here, we present a protocol to trigger an orientational transition of a liquid crystal in response to temperature. Methodologies are described for preparing a sample in order to observe the transition and the detailed transitional evolution.

계면 습윤지의 열역학적 성장에 의해 촉발 된 액정의 방향 전환

In liquid crystal (LC) physical chemistry, molecules near the surface play a great role in controlling bulk orientation. Thus far, mainly to achieve ...

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.

빛에 의해 유도 된 거시적인 진동 모션 액정 네트워크의 준비

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.

레이저 유도 분해 분 광 법에의 한 용융 진공 유도의 정량 분석

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