We acknowledge the services of Stanley Flegler, Carol Flegler, and Abigail Tirrell at the MSU Center for Advanced Microscopy. We thank Ray Clark and Mark Wilson for technical assistance with the set-up of the electrochemical etching apparatus. Earlier contributions from Anne Benjamin, Georg Bollen, Rafael Ferrer, David Lincoln, Stefan Schwarz and Adrian Valverde, and technical assistance from John Yurkon are also acknowledged. This work was partially supported by the National Science Foundation contract no. PHY-1102511 and PHY-1307233, Michigan State University and the Facility for Rare Isotope Beams, and Central Michigan University.

<ol>
	<li>Muller, E. W., Bahadur, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Field+Ionization+of+Gases+at+a+Metal+Surface+and+the+Resolution+of+the+Field+Ion+Microscope.">Field Ionization of Gases at a Metal Surface and the Resolution of the Field Ion Microscope.</a> Phys. Rev. 102, 624 (1956).</li><li>Binnig, G., Rohrer, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Scanning+Tunneling+Microscopy.">Scanning Tunneling Microscopy.</a> Helv. Phys. Acta. 55, 726-735 (1982).</li><li>Melmed, A. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+art+and+science+and+other+aspects+of+making+sharp+tips.">The art and science and other aspects of making sharp tips.</a> J. Vac. Sci. Technol. B. 9, 601-608 (1990).</li><li>Shi, W., Redshaw, M., Myers, E. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Atomic+masses+of+32,33S,+84,86Kr,+and+129,132Xe+with+uncertainties+0.1+ppb.">Atomic masses of 32,33S, 84,86Kr, and 129,132Xe with uncertainties 0.1 ppb.</a> Phys. Rev. A. 72, 022510 (2005).</li><li>Van Dyck, R. S., Zafonte, S. L., Van Liew, S., Pinegar, D. B., Schwinberg, D. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ultraprecise+Atomic+Mass+Measurement+of+the+&#945;+particle+and+4He.">Ultraprecise Atomic Mass Measurement of the &#945; particle and 4He.</a> Phys. Rev. Lett. 92, 220802 (2004).</li><li>Hobara, R., Yoshimoto, S., Hasegawa, S., Sakamoto, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dynamic+electrochemical-etching+technique+for+tungsten+tips+suitable+for+multi-tip+scanning+tunneling+microscopes.">Dynamic electrochemical-etching technique for tungsten tips suitable for multi-tip scanning tunneling microscopes.</a> e-J. Surf. Sci. Nanotechnol. 5, 94-98 (2007).</li><li>Klein, M., Schwitzgebel, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+improved+lamellae+drop-off+technique+for+sharp+tip+preparation+in+scanning+tunneling+microscopy.">An improved lamellae drop-off technique for sharp tip preparation in scanning tunneling microscopy.</a> Rev. Sci. Instrum. 68, 3099-3103 (1997).</li><li>Kerfriden, S., Nahl&#233;, A. H., Campbell, S. A., Walsh, F. C., Smith, J. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+electrochemical+etching+of+tungsten+STM+tips.">The electrochemical etching of tungsten STM tips.</a> Electrochim. Acta. 43, 1939-1944 (1998).</li><li>Lemke, H., G&#246;ddenhenrich, T., Bochem, H. P., Hartmann, U., Heiden, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Improved+microtips+for+scanning+probe+microscopy.">Improved microtips for scanning probe microscopy.</a> Rev. Sci. Instrum. 61, 2538-2538 (1990).</li><li>Song, J. P., Pryds, N. H., Glejb&#248;l, K., M&#248;rch, K. A., Th&#246;l&#233;n, A. R., Christensen, L. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+development+in+the+preparation+of+sharp+scanning+tunneling+microscopy+tips.">A development in the preparation of sharp scanning tunneling microscopy tips.</a> Rev. Sci. Instrum. 64, 900-903 (1993).</li><li>Fowler, R. H., Nordheim, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electron+Emission+in+Intense+Electric+Fields.">Electron Emission in Intense Electric Fields.</a> Proc. R. Soc. Lond. A. , 119-173 (1928).</li><li>Kim, Y. -. G., Choi, E. -. H., Kang, S. -. O., Cho, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Computer-controlled+fabrication+of+ultra-sharp+tungsten+tips.">Computer-controlled fabrication of ultra-sharp tungsten tips.</a> J. Vac. Sci. Technol. B. 16, 2079 (1998).</li><li>Brown, K. L., Tautfest, G. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Faraday-Cup+Monitors+for+High-Energy+Electron+Beams.">Faraday-Cup Monitors for High-Energy Electron Beams.</a> Rev. Sci. Instrum. 27, 696 (1956).</li><li>Redshaw, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fabrication+and+characterization+of+field+emission+points+for+ion+production+in+Penning+trap+applications.">Fabrication and characterization of field emission points for ion production in Penning trap applications.</a> Int. J. Mass Spectrom. 379, 187-193 (2015).</li><li>Ibe, J. P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=On+the+electrochemical+etching+of+tips+for+scanning+tunneling+microscopy.">On the electrochemical etching of tips for scanning tunneling microscopy.</a> J. Vac. Sci. Technol. A. 8, 3570 (1990).</li><li>Ekvall, I., Wahlstr&#246;m, E., Claesson, D., Olin, H., Olsson, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Preparation+and+characterization+of+electrochemically+etched+W+tips+for+STM.">Preparation and characterization of electrochemically etched W tips for STM.</a> Meas. Sci. Technol. 10, 11-18 (1999).</li><li>Schiller, C., Koomans, A. A., van Rooy, T. L., Sch&#246;nenberger, C., Elswijk, H. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Decapitation+of+tungsten+field+emitter+tips+during+sputter+sharpening.">Decapitation of tungsten field emitter tips during sputter sharpening.</a> Surf. Sci. 339, L925-L930 (1995).</li></ol>

The authors have nothing to disclose.

وصفناها إجراءات مباشرة لحفر electrochemically حادة نقاط الانبعاثات الميدان (FEPS) في محلول هيدروكسيد الصوديوم، ولاختبار FEPS من تشغيلها في وضع انبعاث المجال. إجراء الحفر وصفها هو الاختلاف من تقنيات الحالية الإفلات من تقنية الصفيحة 7،8 والعائمة 9،10 تقنية طبقة. ومع ذلك?...

وقد استخدمت نصائح حادة أو نقاط طويل في تطبيقات المجهر، مثل مجهر أيوني (FIM) (1) والمجهر النفقي الماسح (STM) 2، ومجموعة من التقنيات لإنتاج نصائح حادة من مواد مختلفة وضعت 3. ويمكن أيضا أن هذه النصائح حادة أن تعمل كنقاط الانبعاثات الميدان (FEPS) عن طريق تطبيق الجهد العالي لهم، ويكون بمثابة مصدر شعاع الالكترون مريحة. تطبيق واحد من مثل المصدر إنتاج أيون عن طريق تأين تأثير الإلكترون (زعبيل). في محطة إثراء الوقود هو مفيد بشكل خاص في التطبيقات حيث التقلبات في درجات الحرارة التي تنتجها بواعث الحرارية غير مرغوب فيها. على سبيل المثال، إنتاج أيون عن طريق إعمار للصناعة الغاز خلفية أو بخار في درجة عالية من الدقة فخ بينينج 4،5. وهناك طريقة بسيطة لافتعال FEPS هو حفر electrochemically قضبان التنغستن في محلول هيدروكسيد الصوديوم (هيدروكسيد الصوديوم). هذه التقنية هي بسيطة نسبيا لتنفيذ معوقد تبين أن المعدات متواضعة وأن تكون قابلة للتكرار تماما وموثوق بها. ووصف عدد من الأساليب في الأدب ويستمر إدخال تحسينات على هذه التقنيات للمثول 6. نحن هنا تصف طريقة لالنقش الكهروكيميائية من النصائح التنغستن في محلول هيدروكسيد الصوديوم. أسلوبنا هو الاختلاف من الصفيحة الإفلات من تقنية 7،8 والعائمة 9،10 تقنية طبقة. مثل هاتين الطريقتين أنه تمكن من إنتاج اثنين من نصائح من إجراء الحفر واحد. ويظهر صورة للجهاز تجريبي لالحفر النصائح في الشكل 1. <img alt="شكل 1" src="/files/ftp_upload/54030/54030fig1.jpg" /> الشكل 1. جهاز الحفر. الصورة من جهاز التجريبية المستخدمة في الحفر الكهروكيميائية من قضبان التنغستن مع محلول هيدروكسيد الصوديوم. <a href="https://www.jove.com/files/ftp_upload/54030/54030fig1large.jpg" target="_blank">يرجى النقر</a>هنا لعرض نسخة أكبر من هذا الرقم. النقش الكهروكيميائية من التنغستن في قاعدة هيدروكسيد الصوديوم المائية يحدث من خلال عملية ذات مرحلتين. أولا، يتم تشكيل أكاسيد التنغستن وسيطة، والثانية، وهذه الأكاسيد غير قابلة للelectrochemically حل لتشكيل أنيون تنجستات القابلة للذوبان. وصفت هذه العملية، في شكل مبسط، من خلال ردود الفعل اثنين (1) W + 6OH - → WO 3 (S) + 3H 2 O + 6E -، و (2) WO 3 (S) + 2OH - → WO 4 2- + H 2 O. التيار الحفر والحل المولية هيدروكسيد الصوديوم المستخدمة تؤثر على الوقت والجهد المطلوب لحفر من خلال قضيب التنغستن. وتقدم دراسات من هذه الآثار ومناقشتها. الأهم من ذلك، المعلمات النقش يكون لها تأثير على هندسة من النصائح، وعلى هذا النحو، على عملها في وضع انبعاث المجال. الهندسة لل<html> وتميزت نصائح أنتجنا عن طريق التصوير لهم المجهر الإلكتروني الماسح (SEM). هذه الصور يمكن أن تستخدم لتقدير، على سبيل المثال، في دائرة نصف قطرها طرف. وبالإضافة إلى ذلك، كانت تعمل النصائح في وضع انبعاث المجال من خلال تطبيق الجهد السلبي للعادة بضع مئات من فولت إلى بضعة كيلو فولت لهم ورصد مما أدى انبعاث الإلكترون الحالية. العلاقة بين تيار الانبعاث المجال، وأنا، والتطبيقية الجهد التحيز، والخامس، ويمكن وصف هذه المعادلة فاولر-نوردهايم 11 (3) I = AV 2 ه -Cr ممثل المؤسسة / V، حيث r ممثل المؤسسة هي دائرة نصف قطرها الفعلي لطرف، وغير ثابت، وC هو الثاني فاولر-نوردهايم ثابت <img alt="المعادلة 9" src="/files/ftp_upload/54030/54030eq9.jpg" /> ، الذي ب = 6.83 فولت - 3/2 V / نانومتر،030eq11.jpg &quot;/&gt; هي وظيفة عمل من التنغستن ( <img alt="معادلة 11" src="/files/ftp_upload/54030/54030eq11.jpg" /> ≈ 4.5 فولت)، ك هو أحد العوامل التي تعتمد على هندسة (ك ≈ 5)، و <img alt="معادلة 12" src="/files/ftp_upload/54030/54030eq15.jpg" /> هو مصطلح نوردهايم تصحيح الصورة ( <img alt="معادلة 12" src="/files/ftp_upload/54030/54030eq15.jpg" /> ≈ 1) 12. وبالتالي، فإن نصف قطر الفعال للطرف يمكن تحديد ذلك عن طريق قياس التيار الإلكترون بوصفها وظيفة من الجهد التحيز. على وجه التحديد، ويمكن الحصول عليها من منحدر ما يسمى فاولر-نوردهايم (FN) مؤامرة من قانون الجنسية (I / V 2) ضد 1 / V.

<table><tbody><tr><td>Tungsten Rod 0.020&quot; x 12&quot;</td><td>ESPI Metals</td><td>&lt;a href=&quot;http://www.espimetals.com/index.php/online-catalog/467-Tungsten&quot;&gt;http://www.espimetals.com/index.php/online-catalog/467-Tungsten&amp;nbsp;&lt;/a&gt;</td><td>3N8 Purity</td></tr><tr><td>50% by weight NaOH solution</td><td>Sigma-Aldrich</td><td>415413-500ML</td><td>500 ml</td></tr><tr><td>Separatory funnel</td><td>Cole-Parmer</td><td>Item#&amp;nbsp;WU-34506-03</td><td>250 ml</td></tr><tr><td>DC Power supply</td><td>BK Precision</td><td>1672</td><td>Triple Output 0 - 32 V, 0 - 3 A DC Power Supply</td></tr><tr><td>Acetone</td><td>Cole-Parmer</td><td>Item#&amp;nbsp;WU-88000-68</td><td>500 ml</td></tr><tr><td>Data Acquisition Card</td><td>National Instruments</td><td>NI PXI-6221</td><td>16 AI, 24 DIO, 2 AO</td></tr><tr><td>Relay</td><td>Magnecraft</td><td>276 XAXH-5D</td><td>7 A, 30 V DC Reed Relay</td></tr><tr><td>6-way 6&quot; conflat flange cross</td><td>Kurt J Lesker</td><td>C6-0600</td><td></td></tr><tr><td>6&quot; to 2-3/4&quot; conflat zero length reducer flange&amp;nbsp; (x3)</td><td>Kurt J Lesker</td><td>RF600X275</td><td></td></tr><tr><td>2-3/4&quot; conflat flange SHV feedthrough</td><td>Kurt J Lesker</td><td>IFTSG041033</td><td></td></tr><tr><td>2-3/4&quot; conflat flange BNC feedthrough</td><td>Kurt J Lesker</td><td>IFTBG042033</td><td></td></tr><tr><td>2-3/4&quot; conflat flange linear feedthrough</td><td>MDC</td><td>660006, REF# BLM-275-2</td><td></td></tr><tr><td>6&quot; conflat flange blankoff</td><td>Kurt J Lesker</td><td>F0600X000N</td><td></td></tr><tr><td>6&quot; conflat flange window</td><td>Kurt J Lesker</td><td>VPZL-600</td><td></td></tr><tr><td>HV Power supply</td><td>Keithley Instruments</td><td>Keithley Model #2290-5</td><td>0 - 5 kV DC HV Power Supply</td></tr><tr><td>Picoammeter</td><td>Keithley Instruments</td><td>Keithley Model #6485</td><td></td></tr><tr><td>Faraday Cup</td><td>Beam Imaging Solutions</td><td>Model FC-1 Faraday Cup</td><td></td></tr></tbody></table>

electrochemical etching and characterization of sharp field emission points for electron impact ionization

A new variation of the drop-off method for fabricating field emission points by electrochemically etching tungsten rods in a NaOH solution is described. The results of studies in which the etching current and the molarity of the NaOH solution used in the etching process were varied are presented. The investigation of the geometry of the tips, by imaging them with a scanning electron microscope, and by operating them in field emission mode is also described. The field emission tips produced are intended to be used as an electron beam source for ion production via electron impact ionization of background gas or vapor in Penning trap mass spectrometry applications.

دراسة المعلمات الحفر أثناء عملية الحفر يتم تشغيل التيار الكهربائي في الوضع الحالي مستمر. الجهد المطلوب للحفاظ على هذه الزيادات الحالية مستمرة قليلا كما هو محفورا قضيب التنغستن بعيدا...

Watch this Scientific Journal Video about Electrochemical Etching and Characterization of Sharp Field Emission Points for Electron Impact Ionization at JoVE.com

Electrochemical Etching and Characterization of Sharp Field Emission Points for Electron Impact Ionization

A method for electrochemically etching field emission tips is presented. Etching parameters are characterized and the operation of the tips in field emission mode is investigated.

الكهروكيميائية النقش وتوصيف نقاط شارب الميدان الانبعاثات الكترون تأثير التأين

A new variation of the drop-off method for fabricating field emission points by electrochemically etching tungsten rods in a NaOH solution is described. ...

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9.5K Views.  Central Michigan University. A method for electrochemically etching field emission tips is presented. Etching parameters are characterized and the operation of the tips in field emission mode is investigated.

Video: Electrochemical Etching and Characterization of Sharp Field Emission Points for Electron Impact Ionization

Electron Channeling Contrast Imaging for Rapid III-V Heteroepitaxial Characterization

Misfit dislocations in heteroepitaxial layers of GaP grown on Si(001) substrates are characterized through use of electron channeling contrast imaging (ECCI) in a scanning electron microscope (SEM). ECCI allows for imaging of defects and crystallographic features under specific diffraction conditions, similar to that possible via plan-view transmission electron microscopy (PV-TEM). A particular advantage of the ECCI technique is that it requires little to no sample preparation, and indeed can use large area, as-produced samples, making it a considerably higher throughput characterization method than TEM. Similar to TEM, different diffraction conditions can be obtained with ECCI by tilting and rotating the sample in the SEM. This capability enables the selective imaging of specific defects, such as misfit dislocations at the GaP/Si interface, with high contrast levels, which are determined by the standard invisibility criteria. An example application of this technique is described wherein ECCI imaging is used to determine the critical thickness for dislocation nucleation for GaP-on-Si by imaging a range of samples with various GaP epilayer thicknesses. Examples of ECCI micrographs of additional defect types, including threading dislocations and a stacking fault, are provided as demonstration of its broad, TEM-like applicability. Ultimately, the combination of TEM-like capabilities &#8211; high spatial resolution and richness of microstructural data &#8211; with the convenience and speed of SEM, position ECCI as a powerful tool for the rapid characterization of crystalline materials.

The use of electron channeling contrast imaging in a scanning electron microscope to characterize defects in III-V/Si heteroexpitaxial thin films is described. This method yields similar results to plan-view transmission electron microscopy, but in significantly less time due to lack of required sample preparation.

الإلكترون توجيه التباين التصوير لرابيد III-V Heteroepitaxial توصيف

Misfit dislocations in heteroepitaxial layers of GaP grown on Si(001) substrates are characterized through use of electron channeling contrast imaging ...

Atomically Traceable Nanostructure Fabrication

Reducing the scale of etched nanostructures below the 10 nm range eventually will require an atomic scale understanding of the entire fabrication process being used in order to maintain exquisite control over both feature size and feature density. Here, we demonstrate a method for tracking atomically resolved and controlled structures from initial template definition through final nanostructure metrology, opening up a pathway for top-down atomic control over nanofabrication. Hydrogen depassivation lithography is the first step of the nanoscale fabrication process followed by selective atomic layer deposition of up to 2.8 nm of titania to make a nanoscale etch mask. Contrast with the background is shown, indicating different mechanisms for growth on the desired patterns and on the H passivated background. The patterns are then transferred into the bulk using reactive ion etching to form 20 nm tall nanostructures with linewidths down to ~6 nm. To illustrate the limitations of this process, arrays of holes and lines are fabricated. The various nanofabrication process steps are performed at disparate locations, so process integration is discussed. Related issues are discussed including using fiducial marks for finding nanostructures on a macroscopic sample and protecting the chemically reactive patterned Si(100)-H surface against degradation due to atmospheric exposure.

We report a protocol for combining the atomic metrology of the Scanning Tunneling Microscope for surface patterning with selective Atomic Layer Deposition and Reactive Ion Etching. Using a robust process involving numerous atmospheric exposures and transport, 3D nanostructures with atomic metrology are fabricated.

يمكن عزوها بالذرة البنية النانوية تلفيق

Reducing the scale of etched nanostructures below the 10 nm range eventually will require an atomic scale understanding of the entire fabrication process ...

Comprehensive Characterization of Extended Defects in Semiconductor Materials by a Scanning Electron Microscope

Extended defects such as dislocations and grain boundaries have a strong influence on the performance of microelectronic devices and on other applications of semiconductor materials. However, it is still under debate how the defect structure determines the band structure, and therefore, the recombination behavior of electron-hole pairs responsible for the optical and electrical properties of the extended defects. The present paper is a survey of procedures for the spatially resolved investigation of structural and of physical properties of extended defects in semiconductor materials with a scanning electron microscope (SEM). Representative examples are given for crystalline silicon. The luminescence behavior of extended defects can be investigated by cathodoluminescence (CL) measurements. They are particularly valuable because spectrally and spatially resolved information can be obtained simultaneously. For silicon, with an indirect electronic band structure, CL measurements should be carried out at low temperatures down to 5 K due to the low fraction of radiative recombination processes in comparison to non-radiative transitions at room temperature. For the study of the electrical properties of extended defects, the electron beam induced current (EBIC) technique can be applied. The EBIC image reflects the local distribution of defects due to the increased charge-carrier recombination in their vicinity. The procedure for EBIC investigations is described for measurements at room temperature and at low temperatures. Internal strain fields arising from extended defects can be determined quantitatively by cross-correlation electron backscatter diffraction (ccEBSD). This method is challenging because of the necessary preparation of the sample surface and because of the quality of the diffraction patterns which are recorded during the mapping of the sample. The spatial resolution of the three experimental techniques is compared.

The optical, electrical, and structural properties of dislocations and of grain boundaries in semiconductor materials can be determined by experiments performed in a scanning electron microscope. Electron microscopy has been used to investigate cathodoluminescence, electron beam induced current, and diffraction of backscattered electrons.

توصيف شامل العيوب الممتدة في المواد أشباه الموصلات من خلال مجهر المسح الإلكتروني

Extended defects such as dislocations and grain boundaries have a strong influence on the performance of microelectronic devices and on other applications ...

A Novel Method for In Situ Electromechanical Characterization of Nanoscale Specimens

Electrically assisted deformation (EAD) is increasingly being used to improve the formability of metals during processes such as sheet metal rolling and forging. Adoption of this technique is proceeding despite disagreement concerning the underlying mechanism responsible for EAD. The experimental procedure described herein enables a more explicit study compared to previous EAD research by removing thermal effects, which are responsible for disagreement in interpreting previous EAD results. Furthermore, as the procedure described here enables EAD observation in situ and in real time in a transmission electron microscope (TEM), it is superior to existing post-mortem methods that observe EAD effects post-test. Test samples consist of a single crystal copper (SCC) foil having a free-standing tensile test section of nanoscale thickness, fabricated using a combination of laser and ion beam milling. The SCC is mounted to an etched silicon base that provides mechanical support and electrical isolation while serving as a heat sink. Using this geometry, even at high current density (~3,500 A/mm2), the test section experiences a negligible temperature increase (&#60;0.02 &#176;C), thus eliminating Joule heating effects. Monitoring material deformation and identifying the corresponding changes to microstructures, e.g. dislocations, are accomplished by acquiring and analyzing a series of TEM images. Our sample preparation and in situ experiment procedures are robust and versatile as they can be readily utilized to test materials with different microstructures, e.g., single and polycrystalline copper.

A Novel Method for In Situ Electromechanical Characterization of Nanoscale Specimens

Isolating electrical and thermal effects on electrically assisted deformation (EAD) is very difficult using macroscopic samples. Metallic sample micro- and nanostructures together with a custom test procedure have been developed to evaluate the impact of applied current on the formation without joule heating and evolution of dislocations on these samples.

طريقة جديدة ل<em&gt; في الموقع</em&gt; الكهروميكانيكية توصيف عينات النانو

Electrically assisted deformation (EAD) is increasingly being used to improve the formability of metals during processes such as sheet metal rolling and ...

Atom Probe Tomography Analysis of Exsolved Mineral Phases

Element diffusion rates and temperature/pressure control a range of fundamental volcanic and metamorphic processes. Such processes are often recorded in lamellae exsolved from host mineral phases. Thus, the analysis of the orientation, size, morphology, composition and spacing of exsolution lamellae is an area of active research in the geosciences. The conventional study of these lamellae has been conducted by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and more recently with focused ion beam (FIB)-based nanotomography, yet with limited chemical information. Here, we explore the use of atom probe tomography (APT) for the nanoscale analysis of ilmenite exsolution lamellae in igneous titanomagnetite from ash deposits erupted from the active Soufri&#232;re Hills Volcano (Montserrat, British West Indies). APT allows the precise calculation of interlamellar spacings (14&#8211;29 &#177; 2 nm) and reveals smooth diffusion profiles with no sharp phase boundaries during the exchange of Fe and Ti/O between the exsolved lamellae and the host crystal. Our results suggest that this novel approach permits nanoscale measurements of lamellae composition and interlamellar spacing that may provide a means to estimate the lava dome temperatures necessary to model extrusion rates and lava dome failure, both of which play a key role in volcanic hazard mitigation efforts.

Analysis of the morphology, composition, and spacing of exsolution lamellae can provide essential information to understand geological processes related to volcanism and metamorphism. We present a novel application of APT for the characterization of such lamellae and compare this approach to the conventional use of electron microscopy and FIB-based nanotomography.

تحليل التصوير المقطعي الذري للمراحل المعدنية الexsolvedه

Element diffusion rates and temperature/pressure control a range of fundamental volcanic and metamorphic processes. Such processes are often recorded in ...

Environment

Electrochemical Roughening of Thin-Film Platinum Macro and Microelectrodes

This protocol demonstrates a method for electrochemical roughening of thin-film platinum electrodes without preferential dissolution at grain boundaries of the metal. Using this method, a crack free, thin-film macroelectrode surface with up to 40 times increase in active surface area was obtained. The roughening is easy to do in a standard electrochemical characterization laboratory and incudes the application of voltage pulses followed by extended application of a reductive voltage in a perchloric acid solution. The protocol includes the chemical and electrochemical preparation of both a macroscale (1.2 mm diameter) and microscale (20 &#181;m diameter) platinum disc electrode surface, roughening the electrode surface and characterizing the effects of surface roughening on electrode active surface area. This electrochemical characterization includes cyclic voltammetry and impedance spectroscopy and is demonstrated for both the macroelectrodes and the microelectrodes. Roughening increases electrode active surface area, decreases electrode impedance, increases platinum charge injection limits to those of titanium nitride electrodes of same geometry and improves substrates for adhesion of electrochemically deposited films.

This protocol demonstrates a method for electrochemical roughening of thin-film platinum electrodes without preferential dissolution at grain boundaries. The electrochemical techniques of cyclic voltammetry and impedance spectroscopy are demonstrated to characterize these electrode surfaces.

التخوى الكهروكيميائي من رقيقة فيلم البلاتين ماكرو وmicroelectrodes

This protocol demonstrates a method for electrochemical roughening of thin-film platinum electrodes without preferential dissolution at grain boundaries ...

Chemistry

Sample Preparation and Experimental Design for In Situ Multi-Beam Transmission Electron Microscopy Irradiation Experiments

There is a need to understand materials exposed to overlapping extreme environments such as high temperature, radiation, or mechanical stress. When these stressors are combined there may be synergistic effects that enable unique microstructural evolution mechanisms to activate. Understanding of these mechanisms is necessary for the input and refinement of predictive models and critical for engineering of next generation materials. The basic physics and underlying mechanisms require advanced tools to be investigated. The in situ ion irradiation transmission electron microscope (I&#179;TEM) is designed to explore these principles.
To quantitatively probe the complex dynamic interactions in materials, careful preparation of samples and consideration of experimental design is required. Particular handling or preparation of samples can easily introduce damage or features that obfuscate the measurements. There is no one correct way to prepare a sample; however, many mistakes can be made. The most common errors and things to consider are highlighted within. The I&#179;TEM has many adjustable variables and a large potential experimental space, therefore it is best to design experiments with a specific scientific question or questions in mind.
Experiments have been performed on large number of sample geometries, material classes, and with many irradiation conditions. The following are a subset of examples that demonstrate unique in situ capabilities utilizing the I3TEM. Au nanoparticles prepared by drop casting have been used to investigate the effects of single ion strikes. Au thin films have been used in studies on the effects of multibeam irradiation on microstructure evolution. Zr films have been exposed to irradiation and mechanical tension to examine creep. Ag nanopillars were subjected to simultaneous high temperature, mechanical compression, and ion irradiation to study irradiation induced creep as well. These results impact fields including: structural materials, nuclear energy, energy storage, catalysis, and microelectronics in space environments.

<meta charset="utf8"></head><body>إعداد العينات والتصميم التجريبي لتجارب التشعيع المجهري الإلكتروني متعدد الحزم في الموقع

Sample preparation techniques are outlined with specific considerations for in situ ion irradiation TEM experiments. Ion species, energy, and fluence are discussed with methods for how to select and compute them. Finally, procedures for conducting an experiment are described and accompanied by the representative results.

إعداد العينات والتصميم التجريبي لتجارب التشعيع المجهري الإلكتروني متعدد الحزم في الموقع

There is a need to understand materials exposed to overlapping extreme environments such as high temperature, radiation, or mechanical stress. When these ...

3D Depth Profile Reconstruction of Segregated Impurities Using Secondary Ion Mass Spectrometry

The presented protocol combines excellent detection limits (1 ppm to 1 ppb) using secondary ion mass spectrometry (SIMS) with reasonable spatial resolution (~1 &#181;m). Furthermore, it describes how to obtain realistic three-dimensional (3D) distributions of segregated impurities/dopants in solid state materials. Direct 3D depth profile reconstruction is often difficult to achieve due to SIMS-related measurement artifacts. Presented here is a method to identify and solve this challenge. Three major issues are discussed, including the i) nonuniformity of the detector being compensated by flat-field correction; ii) vacuum background contribution (parasitic oxygen counts from residual gases present in the analysis chamber) being estimated and subtracted; and iii)&#160;performance of all steps within a stable timespan of the primary ion source. Wet chemical etching is used to reveal the position and types of dislocation in a material, then the SIMS result is superimposed on images obtained via scanning electron microscopy (SEM). Thus, the position of agglomerated impurities can be related to the position of certain defects. The method is fast and does not require sophisticated sample preparation stage; however, it requires a high-quality, stable ion source, and the entire measurement must be performed quickly to avoid deterioration of the primary beam parameters.

The presented method describes how to identify and solve measurement artifacts related to secondary ion mass spectrometry as well as obtain realistic 3D distributions of impurities/dopants in solid state materials.

3D عمق الشخصي إعادة بناء الشوائب المنفصلة باستخدام مطياف الكتلة الأيونية الثانوية

The presented protocol combines excellent detection limits (1 ppm to 1 ppb) using secondary ion mass spectrometry (SIMS) with reasonable spatial ...

Nanoscale Characterization of Liquid-Solid Interfaces by Coupling Cryo-Focused Ion Beam Milling with Scanning Electron Microscopy and Spectroscopy

Physical and chemical processes at solid-liquid interfaces play a crucial role in many natural and technological phenomena, including catalysis, solar energy and fuel generation, and electrochemical energy storage. Nanoscale characterization of such interfaces has recently been achieved using cryogenic electron microscopy, thereby providing a new path to advancing our fundamental understanding of interface processes.
This contribution provides a practical guide to mapping the structure and chemistry of solid-liquid interfaces in materials and devices using an integrated cryogenic electron microscopy approach. In this approach, we pair cryogenic sample preparation which allows stabilization of solid-liquid interfaces with cryogenic focused ion beam (cryo-FIB) milling to create cross-sections through these complex buried structures. Cryogenic scanning electron microscopy (cryo-SEM) techniques performed in a dual-beam FIB/SEM enable direct imaging as well as chemical mapping at the nanoscale. We discuss practical challenges, strategies to overcome them, as well as protocols for obtaining optimal results. While we focus in our discussion on interfaces in energy storage devices, the methods outlined are broadly applicable to a range of fields where solid-liquid interface play a key role.

Cryogenic Focused Ion Beam (FIB) and Scanning Electron Microscopy (SEM) techniques can provide key insights into the chemistry and morphology of intact solid-liquid interfaces. Methods for preparing high quality Energy Dispersive X-ray (EDX) spectroscopic maps of such interfaces are detailed, with a focus on energy storage devices.

توصيف المقياس النانوي للواجهات السائلة الصلبة عن طريق اقتران طحن الحزمة الأيونية المركزة على التبريد مع المجهر الإلكتروني الماسح والتحليل الطيفي

Physical and chemical processes at solid-liquid interfaces play a crucial role in many natural and technological phenomena, including catalysis, solar ...

الكهروكيميائية النقش وتوصيف نقاط شارب الميدان الانبعاثات الكترون تأثير التأين

Summary

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الإلكترون توجيه التباين التصوير لرابيد III-V Heteroepitaxial توصيف

يمكن عزوها بالذرة البنية النانوية تلفيق

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طريقة جديدة ل

تحليل التصوير المقطعي الذري للمراحل المعدنية الexsolvedه

التخوى الكهروكيميائي من رقيقة فيلم البلاتين ماكرو وmicroelectrodes

إعداد العينات والتصميم التجريبي لتجارب التشعيع المجهري الإلكتروني متعدد الحزم في الموقع

إعداد العينات والتصميم التجريبي لتجارب التشعيع المجهري الإلكتروني متعدد الحزم في الموقع

3D عمق الشخصي إعادة بناء الشوائب المنفصلة باستخدام مطياف الكتلة الأيونية الثانوية

توصيف المقياس النانوي للواجهات السائلة الصلبة عن طريق اقتران طحن الحزمة الأيونية المركزة على التبريد مع المجهر الإلكتروني الماسح والتحليل الطيفي