This research was primarily sponsored by the Laboratory Directed Research and Development Program of Oak&#160;Ridge National Laboratory (ORNL), managed by UT-Battelle LLC, for the U.S. Department of Energy (DOE). Part of the development to introduce water vapor into the&#160;in situ&#160;gas cell was sponsored by the U.S. DOE, Office of Energy Efficiency and Renewable Energy, Bio-Energy Technologies Office, under contract DE-AC05-00OR22725 (ORNL) with UT-Battle, LLC, and in collaboration with the Chemical Catalysis for Bioenergy (ChemCatBio) Consortium, a member of the Energy Materials Network (EMN). This work was authored in part by the National Renewable Energy Laboratory, operated by Alliance for Sustainable Energy, LLC, for the U.S. DOE under Contract No. DE-AC36-08GO28308.&#160;Part of the microscopy was conducted at the Center for Nanophase Materials Sciences (CNMS), which is a DOE Office of Science User Facility. Early development of&#160;in situ&#160;STEM capabilities was sponsored by the Propulsion Materials Program, Vehicle Technologies Office, U.S. DOE. &#160;We thank Dr. John Damiano, Protochips Inc., for useful technical discussions. The authors thank Rosemary Walker and Kase Clapp, ORNL production team, for support with movie production. The views expressed in this article do not necessarily represent the views of the DOE or the U.S. Government. The U.S. Government retains and the publisher, by accepting the article for publication, acknowledges that the U.S. Government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this work, or allow others to do so, for U.S. Government purposes.

1. E-chip preparation
<ol>
	<li>Direct powder deposition by drop-casting from a colloidal solution (Figure 2A).
	<ol>
		<li>Crush the powder if the powder particle aggregates are too large. Do this using a small mortar and pestle (crushed aggregates should be &#60;5 &#181;m in size). Mix a small amount (e.g., ~0.005 mg, amount determined by experience) of powder in 2 mL of the solvent (e.g., isopropanol or ethanol).</li>
		<li>Sonicate the mixture for around 5 min to create a colloidal suspension.</li>
		<li>Place the E-chip on the E-chip retaining fixture. Drop cast approximately 1 &#181;L of the suspension using a 0.5-2.5 &#181;L micro-pipette directly onto the E-chip.</li>
		<li>Clean the Au contacts to remove the suspension with an absorbent paper point while viewing through a stereo microscope.</li>
	</ol>
	</li>
	<li>Direct powder deposition through a mask (Figure 2B).
	<ol>
		<li>Crush the powder (e.g., Pt/TiO2) dry, if powder particles are too large (as in 1.1.1).</li>
		<li>Place a new clean E-chip on the E-chip retaining fixture (Figure 3D). Use a mask, which is another E-chip with the SixNy membrane removed (by breaking it with tweezers or compressed gas) and place it directly onto the E-chip within the fixture.</li>
		<li>Use the top plate to clamp a new clean E-chip and a mask together within the fixture.</li>
		<li>Deposit a small amount of the powder using a spatula directly on the silicon nitrile membrane in the mask.</li>
		<li>Gently vibrate the fixture to shake the particles down to the E-chip. This can either be done using a vacuum tweezer unit by holding the fixture to the top of the unit while it is running or using a sonication unit and placing the fixture in a dry beaker.</li>
		<li>Shake off the excess powder, disassemble the system and inspect the placement of dry powder on the E-chip using a stereo microscope.</li>
	</ol>
	</li>
	<li>Deposition method by either electron beam evaporation, ion, or magnetron sputtering. 
	NOTE: This method is used to create either a single-element system or model alloy specimens of known geometry and composition.
	<ol>
		<li>Create a pattern mask (Figure 3). 
		NOTE: Prepare the pattern mask in advance since it takes some time.</li>
		<li>Use a spacer chip with removed SixNy membrane. In this experiment, an E-chip commonly used in liquid-cell experiments was used after gently breaking out the SixNy membrane which resulted in 50 x 250 &#181;m opening. This spacer chip with removed SixNy membrane will be combined with another chip, having an array of holes (e.g., silicon nitride (SiN) Microporous TEM Window 33).</li>
		<li>Use cyanoacrylate (CA) glue (Table of Materials) to attach the SiN Microporous TEM Window face down (SiN pattern film away from the spacer chip) over the 50 x 250 &#181;m opening following the manufacturer&#39;s recommendation (Figure&#160;3B,C).</li>
		<li>Repeat the procedure to prepare as many pattern masks as needed, depending on the planned experiments.</li>
		<li>Place a new clean E-chip on the E-chip fixture (Figure 3D).</li>
		<li>Place the pattern mask on the E-chip (Figure&#160;3C,D).</li>
		<li>Cover with the top plate and clamp it (Figure 3D).</li>
		<li>Use either electron beam evaporation, ion sputtering or magnetron sputtering deposition techniques. These are the recommended methods used to sputter material of interest directly through the pattern mask. 
		NOTE: It may be important to purge the deposition system to remove residual oxygen prior to the deposition for higher purity material deposits33.</li>
		<li>Disassemble the system and inspect the E-chip with a stereo microscope to ensure good adherence of the deposited material on the E-chip&#39;s SixNy membrane.</li>
	</ol>
	</li>
	<li>Focused ion beam (FIB) milling (Figure 2C).
	<ol>
		<li>Prepare a standard TEM lamella using the FIB. Use low kV (e.g., 2-5 kV) for the final milling step to remove damage caused by FIB milling at high voltages (30-40 kV).</li>
		<li>Place the TEM lamella on the E-chip using standard FIB procedures. Do not damage the SixNy membrane when attaching the FIB-prepared TEM lamella to the E-chip. See Allard et al.34 and other publications30,35,36 for details of the variety of methods using Xe-PFIB and Ga-FIB instruments for lamella preparation.</li>
	</ol>
	</li>
</ol>
2. Preparation of the atmosphere (CCGR-TEM) holder
<ol>
	<li>Download the desired calibration file.</li>
	<li>Measure the resistance of the SiC heater to ensure that it is within the resistance range for that particular E-chip calibration as provided by the CCGR manufacturer.</li>
	<li>Remove the clamp from the CCGR-TEM holder.</li>
	<li>Clean the tip of the CCGR-TEM holder using absorbent paper points and/or compressed air, making sure no debris remains on the O-ring grooves. Then place the special double-gasket seal within the tip.</li>
	<li>Place the spacer chip into the CCGR-TEM holder.</li>
	<li>Place the E-chip containing the specimen that was prepared by one of the methods mentioned in section 1 with the heater contacts down onto the spacer chip, making a proper connection to the electrical contacts of the flex-cable within the holder.</li>
	<li>Position the holder clamp plate on the top of the E-chip using tweezers, place the screws into the designated location at the tip of the CCGR-TEM holder, then torque the set screws with a final torque to 0.2 lb-ft.</li>
	<li>Measure again, the resistance of the SiC heater after assembling the CCGR-TEM holder to ensure that it is within the resistance range for that particular E-chip calibration as provided by the CCGR manufacturer. 
	&#8203;NOTE: Here, a special adapter is used, which plugs directly into the holder&#39;s electrical connections. This allows for the resistance measurements to be made through the CCGR-TEM holder and paired microchip devices assembly while fully assembled into the holder.</li>
</ol>
3. Preparation of the experimental setup
<ol>
	<li>Bake and pump down the system (manifold, holder, gas tanks, and RGA chamber) overnight, either with or without the holder connected by pressing the Bake button in the gas-control software.</li>
	<li>Load the holder into the scanning transmission electron microscope and connect the gas tubing from the manifold to the CCGR-TEM holder.</li>
	<li>For the experiment, pump and purge the system with an inert gas (e.g., Ar or N2) twice from 100 Torr to 0.5 Torr.</li>
	<li>Perform a final pump and purge from 100 Torr to 0.001 Torr. This will ensure that the entire gas delivery system, from the gas manifold to the holder, is cleaned and flushed with inert gas.</li>
	<li>Residual gas analyzer - During the pump and purge procedure, turn on the RGA system to warm up the filament.</li>
</ol>
4. Preparing the water vapor delivery system (VDS)
NOTE: These instructions are for specific experiments that involve controlled delivery of gas in vapor form (e.g., water vapor). Gas delivery control is through the gas-control software provided by the manufacturer (Table of Materials).
<ol>
	<li>Attach the purge gas (e.g., N2) to the VDS, turn the lever knob to Exhaust, and then turn to the Park position.</li>
	<li>Purge the VDS (repeat 4.1) by flowing inert gas three times or until no more liquid is present.</li>
	<li>Turn the lever knob to the Park position and attach the VDS to the manifold.</li>
	<li>Turn the lever knob to the Fill position and remove the purge gas line.</li>
	<li>Set the vapor pressure to 18.7 Torr in the gas-control&#160;software.</li>
	<li>In the software, pump the VDS to vacuum (0.1 Torr) by selecting the input line and pressing the pump button.</li>
	<li>Fill the VDS with water (2 mL) via a syringe and tubing. 
	&#8203;NOTE: If higher purity vapor is needed, additional purging steps may be required.</li>
</ol>
5. Running the reaction
<ol>
	<li>Make sure all gases that are to be used in the experiments (e.g., N2, water vapor, and O2) are connected to the manifold.</li>
	<li>With the gas-control software under Naming, set the name(s) for the gas(es) required for the reaction and save the raw &#34;.csv&#34; file such that a running log file is generated for the experiment.</li>
	<li>Under the E-chip Setup, select the associated calibration file (i.e., as described in 2.5) for the E-chip being used and Run Calibration. As previously mentioned in the Introduction section, each E-chip is temperature calibrated using infrared radiation (IR) imaging from the manufacturer.</li>
	<li>Under Pump and Purge, see Preparation of Experimental Setup.</li>
	<li>Under Gas Control, select the desired gas name and its composition (e.g., select percentage for each gas) for the experiment.</li>
	<li>Under Temperature, select the desired heating rate and target temperature&#160;for the temperature of interest for the experiment and press the Start button.</li>
	<li>Start flowing the gas by pressing the Start button under the Gas Control section.</li>
</ol>
6. End of the experiment
<ol>
	<li>Once the reaction is complete, stop flowing the gas, turn off the temperature knob, and end the session using the Pump and Purge procedure (e.g., depending on the reaction that was performed, perform Pump and Purge procedure from 100 Torr to 0.1 Torr 2-3 times).</li>
	<li>Prior to removing the in situ CCGR-TEM holder from the electron microscope, ensure that that holder pressure is brought back up to atmospheric pressure.</li>
</ol>

<ol>
	<li>Allard, L. F., 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=A+new+MEMS-based+system+for+ultra-high-resolution+imaging+at+elevated+temperatures.">A new MEMS-based system for ultra-high-resolution imaging at elevated temperatures.</a> Microscopy Research and Technique. 72 (3), 208-215 (2009).</li><li>Allard, L. F., 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=Novel+MEMS-based+gas-cell/heating+specimen+holder+provides+advanced+imaging+capabilities+for+in+situ+reaction+studies.">Novel MEMS-based gas-cell/heating specimen holder provides advanced imaging capabilities for in situ reaction studies.</a> Microscopy and Microanalysis. 18 (4), 656-666 (2012).</li><li>Allard, L. F., 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=Innovative+closed-cell+reactor+permits+in+situ+heating+and+gas+reactions+with+atomic+resolution+at+atmospheric+pressure.">Innovative closed-cell reactor permits in situ heating and gas reactions with atomic resolution at atmospheric pressure.</a> Microscopy and Microanalysis. 18 (2), 1118-1119 (2012).</li><li>Allard, L. F., 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=Controlled+in+situ+gas+reaction+studies+of+catalysts+at+high+temperature+and+pressure+with+atomic+resolution.">Controlled in situ gas reaction studies of catalysts at high temperature and pressure with atomic resolution.</a> Microscopy and Microanalysis. 20 (3), 1572-1573 (2014).</li><li>Allard, L. F., 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=computer-controlled+in+situ+gas+reactions+via+a+mems-based+closed-cell+system.">computer-controlled in situ gas reactions via a mems-based closed-cell system.</a> Microscopy and Microanalysis. 21 (3), 97-98 (2015).</li><li>Unocic, K. A., Shin, D., Unocic, R. R., Allard, L. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=NiAl+oxidation+reaction+processes+studied+in+situ+using+MEMS-based+closed-cell+gas+reaction+transmission+electron+microscopy.">NiAl oxidation reaction processes studied in situ using MEMS-based closed-cell gas reaction transmission electron microscopy.</a> Oxidation of Metals. 88 (3-4), 495-508 (2017).</li><li>Dai, S., 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=Revealing+surface+elemental+composition+and+dynamic+processes+involved+in+facet-dependent+oxidation+of+Pt3Co+nanoparticles+via+in+situ+transmission+electron+microscopy.">Revealing surface elemental composition and dynamic processes involved in facet-dependent oxidation of Pt3Co nanoparticles via in situ transmission electron microscopy.</a> Nano Letters. 17 (8), 4683-4688 (2017).</li><li>Dai, S., Zhang, S., Katz, M. B., Graham, G. W., Pan, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+Situ+observation+of+Rh-CaTiO3+catalysts+during+reduction+and+oxidation+treatments+by+transmission+electron+microscopy.">In Situ observation of Rh-CaTiO3 catalysts during reduction and oxidation treatments by transmission electron microscopy.</a> ACS Catalysis. 7 (3), 1579-1582 (2017).</li><li>Burke, M. G., Bertali, G., Prestat, E., Scenini, F., Haigh, S. 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+application+of+in+situ+analytical+transmission+electron+microscopy+to+the+study+of+preferential+intergranular+oxidation+in+Alloy+600.">The application of in situ analytical transmission electron microscopy to the study of preferential intergranular oxidation in Alloy 600.</a> Ultramicroscopy. 176, 46 (2017).</li><li>Unocic, K. A., 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=Introducing+and+controlling+water+vapor+in+closed-cell+in+situ+electron+microscopy+gas+reactions.">Introducing and controlling water vapor in closed-cell in situ electron microscopy gas reactions.</a> Microscopy and Microanalysis. 26 (2), 229-239 (2020).</li><li>Vendelbo, S. B., 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=Visualization+of+oscillatory+behaviour+of+Pt+nanoparticles+catalysing+CO+oxidation.">Visualization of oscillatory behaviour of Pt nanoparticles catalysing CO oxidation.</a> Nature Materials. 13 (9), 884-890 (2014).</li><li>Moliner, 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=Reversible+transformation+of+Pt+nanoparticles+into+single+atoms+inside+high-silica+chabazite+zeolite.">Reversible transformation of Pt nanoparticles into single atoms inside high-silica chabazite zeolite.</a> Journal of the American Chemical Society. 138 (48), 15743-15750 (2016).</li><li>Dagle, V., 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=Single-step+conversion+of+ethanol+to+n-butenes+over+Ag-ZrO2/SiO2+catalysts.">Single-step conversion of ethanol to n-butenes over Ag-ZrO2/SiO2 catalysts.</a> ACS Catalyst. 10 (18), 10602-10613 (2020).</li><li>Chi, 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=Surface+faceting+and+elemental+diffusion+behaviour+at+atomic+scale+for+alloy+nanoparticles+during+in+situ+annealing.">Surface faceting and elemental diffusion behaviour at atomic scale for alloy nanoparticles during in situ annealing.</a> Nature Communications. 6 (1), 1-9 (2015).</li><li>Zhao, X., 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=Single-iron+site+catalysts+with+self-assembled+dual-size+architecture+and+hierarchical+porosity+for+proton-exchange+membrane+fuel+cells.">Single-iron site catalysts with self-assembled dual-size architecture and hierarchical porosity for proton-exchange membrane fuel cells.</a> Applied Catalysis B: Environmental. 279, 119400 (2020).</li><li>Baddour, F. G., 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=An+Exceptionally+mild+and+scalable+solution-phase+synthesis+of+molybdenum+carbide+nanoparticles+for+thermocatalytic+CO2+hydrogenation.">An Exceptionally mild and scalable solution-phase synthesis of molybdenum carbide nanoparticles for thermocatalytic CO2 hydrogenation.</a> Journal of the American Chemical Society. 142 (2), 1010-1019 (2019).</li><li>Yan, 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=Methanol+oxidative+dehydrogenation+and+dehydration+on+carbon+nanotubes:+active+sites+and+basic+reaction+kinetics.">Methanol oxidative dehydrogenation and dehydration on carbon nanotubes: active sites and basic reaction kinetics.</a> Sustainable Energy Fuels. 10, 4952-4959 (2020).</li><li>Unocic, R. R., Jungjohann, K., Mehdi, B. L., Browning, N. D., Wang, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+situ+electrochemical+scanning/transmission+electron+microscopy+of+electrode-electrolyte+interfaces.">In situ electrochemical scanning/transmission electron microscopy of electrode-electrolyte interfaces.</a> MRS Bulletin. 45, 1-8 (2020).</li><li>LaGrow, A. P., Lloyd, D. C., Gai, P. L., Boyes, E. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+situ+scanning+transmission+electron+microscopy+of+Ni+nanoparticle+redispersion+via+the+reduction+of+hollow+NiO.">In situ scanning transmission electron microscopy of Ni nanoparticle redispersion via the reduction of hollow NiO.</a> Chemistry of Materials. 30 (1), 197-203 (2017).</li><li>Liu, L., Zakharov, D. N., Arenal, R., Concepcion, P., Stach, E. A., Corma, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evolution+and+stabilization+of+subnanometric+metal+species+in+confined+space+by+in+situ+TEM.">Evolution and stabilization of subnanometric metal species in confined space by in situ TEM.</a> Nature Communications. 9 (1), 574 (2018).</li><li>Wu, Y. A., 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=Visualizing+redox+dynamics+of+a+single+Ag/AgCl+heterogeneous+nanocatalyst+at+atomic+resolution.">Visualizing redox dynamics of a single Ag/AgCl heterogeneous nanocatalyst at atomic resolution.</a> ACS Nano. 10 (3), 3738-3746 (2016).</li><li>Li, Y., 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=Complex+structural+dynamics+of+nanocatalysts+revealed+in+operando+conditions+by+correlated+imaging+and+spectroscopy+probes.">Complex structural dynamics of nanocatalysts revealed in operando conditions by correlated imaging and spectroscopy probes.</a> Nature Communications. 6 (1), 7583 (2015).</li><li>Hansen, P. L., 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=Atom-resolved+imaging+of+dynamic+shape+changes+in+supported+copper+nanocrystals.">Atom-resolved imaging of dynamic shape changes in supported copper nanocrystals.</a> Science. 295 (5562), 2053-2055 (2002).</li><li>Creemer, J. F., 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=Atomic-scale+electron+microscopy+at+ambient+pressure.">Atomic-scale electron microscopy at ambient pressure.</a> Progress in Materials Science. 108, 993-998 (2008).</li><li>Was, G. S., Petti, D., Ukai, S., Zinkle, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Materials+for+future+nuclear+energy+systems.">Materials for future nuclear energy systems.</a> Journal of Nuclear Materials. 527, 151837 (2019).</li><li>Unocic, K. A., Yamamoto, Y., Pint, B. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+Al+and+Cr+content+on+air+and+steam+oxidation+of+FeCrAl+alloys+and+commercial+APMT+alloy.">Effect of Al and Cr content on air and steam oxidation of FeCrAl alloys and commercial APMT alloy.</a> Oxidation of Metals. 87 (3-4), 431-441 (2017).</li><li>Zinkle, S. J., 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=Fusion+materials+science+and+technology+research+opportunities+now+and+during+the+ITER+era.">Fusion materials science and technology research opportunities now and during the ITER era.</a> Fusion Engineering and Design. 89 (7-8), 1579-1585 (2014).</li><li>Quadakkers, W. J., Olszewski, T., Piron-Abellan, J., Shemet, V., Singheiser, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Oxidation+of+metallic+materials+in+simulated+CO2/H2O-rich+service+environments+relevant+to+an+oxyfuel+plant.">Oxidation of metallic materials in simulated CO2/H2O-rich service environments relevant to an oxyfuel plant.</a> Materials Science Forum. 696, 194-199 (2011).</li><li>Gleeson, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Thermal+barrier+coatings+for+aeroengine+applications.">Thermal barrier coatings for aeroengine applications.</a> Journal of Propulsion and Power. 22 (2), 375-383 (2006).</li><li>Unocic, K. A., Allard, L. F., Coffey, D. W., More, K. L., Unocic, R. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Novel+method+for+precision+controlled+heating+of+TEM+thin+sections+to+study+reaction+processes.">Novel method for precision controlled heating of TEM thin sections to study reaction processes.</a> Microscopy and Microanalysis. 20, 1628-1629 (2014).</li><li>Idrobo, J. C., 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=Temperature+measurement+by+a+nanoscale+electron+probe+using+energy+gain+and+loss+spectroscopy.">Temperature measurement by a nanoscale electron probe using energy gain and loss spectroscopy.</a> Physical Review Letters. 120 (9), 095901 (2018).</li><li>Unocic, K. A., Datye, A. K., Bigelow, W. C., Allard, L. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Water+vapor+in+closed-cell+in+situ+gas+reactions:+Initial+experiments.">Water vapor in closed-cell in situ gas reactions: Initial experiments.</a> Microscopy and Microanalysis. 23 (1), 940-941 (2017).</li><li>Allard, L. F., Meyer, H. M., Hensley, D. K., Bigelow, W. C., Unocic, K. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Model+"alloy"+specimens+for+MEMS-based+closed-cell+gas-reactions.">Model "alloy" specimens for MEMS-based closed-cell gas-reactions.</a> Microscopy and Microanalysis. 23 (1), 908-909 (2017).</li><li>Allard, L. F., 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=The+utility+of+Xe-plasma+FIB+for+preparing+aluminum+alloy+specimens+for+MEMS-based+in+situ+double-tilt+heating+experiments.">The utility of Xe-plasma FIB for preparing aluminum alloy specimens for MEMS-based in situ double-tilt heating experiments.</a> Microscopy and Microanalysis. 25 (2), 1442-1443 (2019).</li><li>Schilling, S., Janssen, A., Zaluzec, N. J., Burke, M. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Practical+aspects+of+electrochemical+corrosion+measurements+during+in+situ+analytical+transmission+electron+microscopy+(TEM)+of+austenitic+stainless+steel+in+aqueous+media.">Practical aspects of electrochemical corrosion measurements during in situ analytical transmission electron microscopy (TEM) of austenitic stainless steel in aqueous media.</a> Microscopy and Microanalysis. 23 (4), 741-750 (2017).</li><li>Zhong, X. L., Schilling, S., Zaluzec, N. J., Burke, M. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sample+preparation+methodologies+for+in+situ+liquid+and+gaseous+cell+analytical+transmission+electron+microscopy+of+electropolished+specimens.">Sample preparation methodologies for in situ liquid and gaseous cell analytical transmission electron microscopy of electropolished specimens.</a> Microscopy and Microanalysis. 22 (6), 1350-1359 (2016).</li><li>Duchamp, M., Xu, Q., Dunin-Borkowski, R. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Convenient+preparation+of+high-quality+specimens+for+annealing+experiments+in+the+transmission+electron+microscope.">Convenient preparation of high-quality specimens for annealing experiments in the transmission electron microscope.</a> Microscopy and Microanalysis. 20 (6), 1638-1645 (2014).</li><li>Unocic, K. A., Mills, M. J., Daehn, G. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+gallium+focused+ion+beam+milling+on+preparation+of+aluminum+thin+foils.">Effect of gallium focused ion beam milling on preparation of aluminum thin foils.</a> Journal of Microscopy. 240 (3), 227-238 (2010).</li><li>Unocic, R. R., 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=Probing+battery+chemistry+with+liquid+cell+electron+energy+loss+spectroscopy.">Probing battery chemistry with liquid cell electron energy loss spectroscopy.</a> Chemical Communications. 51 (91), 16377-16380 (2015).</li></ol>

The authors declare no conflicts of interest.
This manuscript has been authored by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-public-access-plan).

In the present work, an approach to perform in situ STEM reactions with and without water vapor is demonstrated. The critical step within the protocol is E-chip preparation and maintaining its integrity during the loading procedure. The limitation of the technique is (a) the specimen size and its geometry to fit the nominal 5-&#181;m gap between paired (MEMS)-based silicon microchip devices as well as (b) a total pressure used in the experiments with water vapor since the highest total pressure depends on the qu...

There is a need to obtain detailed information on how a material undergoes structural and chemical changes under reactive gas exposure and at elevated temperatures. In situ closed-cell gas reaction (CCGR) scanning transmission electron microscopy (STEM) was developed specifically to study the dynamic changes occurring in a wide range of material systems (e.g., catalysts, structural materials, carbon nanotubes, etc.) when subjected to elevated temperatures, different gaseous environments, and pressures from vacuum to full atmospheric pressure1,2,3,4,5,6,7,8,9,10,11,12. This approach can be beneficial in several cases, e.g., in the accelerated development of next-generation catalysts that are important for a number of industrial conversion processes, such as the single-step conversion of ethanol to n-butenes over Ag-ZrO2/SiO213, catalysts for the oxygen reduction reaction&#160;and hydrogen evolution reaction in fuel cell applications14,15, catalytic CO2 hydrogenation16, methanol dehydrogenation to formaldehyde or dehydration to dimethyl ether that use either metal catalysts or multi-walled carbon nanotubes in a methanol conversion reaction in the presence of oxygen17. Recent applications of this in situ technique for catalysis research1,2,7,8,10,11,12,18,19,20,21,22 have provided new insight into catalyst dynamic shape changes10,11,23, faceting7, growth, and mobility8,20,24. Moreover, in situ CCGR-STEM can be used to investigate the high-temperature oxidation behavior of structural materials that are exposed to aggressive environments, from gas turbine engines to next-generation fission and fusion reactors, where not only strength, fracture toughness, weldability, or radiation are important but also high-temperature oxidation resistance25,26,27,28,29. Specific to structural alloys, in situ CCGR-STEM experiments allow for dynamic tracking of diffusion-induced grain boundary migration under reducing conditions9 and measurements of oxidation kinetics at high temperature5,6,30. For several decades prior to the recent development of CCGR technologies, in situ gas reaction studies were conducted using dedicated environmental TEMs (E-TEMs). A detailed comparison of E-TEM and CCGR-STEM has been previously addressed10; therefore, E-TEM capabilities are not discussed further in the present work.
In this work, a commercially available system (Table of Materials) comprising&#160;a computer-controlled manifold (gas delivery system) and a specially designed CCGR TEM holder that utilizes a pair of microelectromechanical (MEMS)-based silicon microchip devices (e.g., spacer chip and &#34;E-chip&#34; heater (Table of Materials)) were used. Each E-chip&#160;supports an amorphous, electron-transparent SixNy membrane. The spacer chip has a 50 nm thick SixNy membrane with a 300 x 300 &#181;m2 viewing area and 5 &#181;m thick epoxy-based photoresist (SU-8) &#34;spacer&#34; contacts that are microfabricated to provide a gas flow path and maintain a physical offset between the two paired microchips (Figure 1A). A portion of the E-chip is covered with a low conductivity ~100 nm SiC ceramic membrane; the membrane has a 3 x 2 array of 8 &#181;m-diameter etched holes overlapped by a ~30 nm thick amorphous SixNy membrane (SixNy viewing area) (Figure 1A and Figure 2D), through which images are recorded. The E-chip serves a dual role as both specimen support and heater6. Au contacts are microfabricated onto the E-chip to allow for resistive heating of the SiC membrane. Each E-chip is calibrated using&#160;infrared radiation (IR) imaging methods (Table of Materials)2 and has been shown to be accurate to within &#177;5%31. Temperature calibration is independent of the gas composition and pressure, thereby providing independent control over reaction temperatures under any chosen gas conditions. The benefit of a thin-film heater is that temperatures up to 1,000 &#176;C can be reached within milliseconds. In order to perform the reaction, the E-chip is placed on the top of the spacer chip, creating the closed-cell &#34;sandwich&#34; that isolates the environment around the specimen from the high vacuum of the TEM column. The advantage of this setup is that reactions can be performed from low pressures up to atmospheric pressure (760 Torr) with single or mixed gases and under static or flow conditions. The MEMS devices are secured with a clamp (Figure 1B) that allows the holder to be inserted within the mm-sized gap of the objective lens pole piece in an aberration-corrected S/TEM instrument (Table of Materials) (Figure 1C). Modern in situ S/TEM holders include integrated micro-fluidic tubing (capillaries) that are connected to the external stainless-steel tubing, which in turn is connected to the gas delivery system (manifold). An electronic control system permits the controlled delivery and flow of reactant gas through the gas cell. Gas flow and temperature are operated by a custom workflow-based software package provided by the manufacturer (Table of Materials)10,32. The software controls three gas input lines, two internal experimental-gas delivery tanks, and a receiving tank for gas flow returning from the cell during the experiment (Figure 1D).
Due to the variability of materials and their form factor, we first focus on several specimen deposition methods on the E-chip, then outline protocols for performing quantitative in situ/operando experiments with controlled temperature, gas mixing and flow.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Atmosphere Clarity Software</td>
			<td>Protochips</td>
			<td>6.5.14</td>
			<td></td>
		</tr>
		<tr>
			<td>Atmosphere Large Heating E-chips, 300 x 300 window, no spacer</td>
			<td>Protochips</td>
			<td>EAT-33AA-10</td>
			<td>microchip device</td>
		</tr>
		<tr>
			<td>Atmosphere Small E-chips, 300 x 300 micron window, 5 micron SU-8 spacer</td>
			<td>Protochips</td>
			<td>EAB-33W-10</td>
			<td>microchip device</td>
		</tr>
		<tr>
			<td>JEOL 2200FS</td>
			<td>JEOL</td>
			<td></td>
			<td>microscope</td>
		</tr>
		<tr>
			<td>M-bond 610</td>
			<td>Electron Microscopy Sciences</td>
			<td>50410-30</td>
			<td>cyanoacrylate (CA) glue</td>
		</tr>
		<tr>
			<td>Mikron M9103 IR camera</td>
			<td>Micron</td>
			<td></td>
			<td>This is used by Protochips/ not available</td>
		</tr>
		<tr>
			<td>Protochips &#8220;Fusion&#8221; E-chips</td>
			<td>Protochips</td>
			<td></td>
			<td>spacer chip with removed SixNy membrane</td>
		</tr>
		<tr>
			<td>Protochips Atmosphere 200</td>
			<td>Protochips</td>
			<td>prototype</td>
			<td>software</td>
		</tr>
		<tr>
			<td>Residual Gas Analyzer R100 (RGA)</td>
			<td>Stanford Research Systems</td>
			<td>R100 SRS</td>
			<td></td>
		</tr>
	</tbody>
</table>

performing in situ closed-cell gas reactions in the transmission electron microscope

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

Specimens for MEMS-Based Closed-Cell Gas Reactions: 
Direct powder deposition by drop casting from a colloidal solution and through a mask 
Depending on the material to be studied, there are a number of different ways to prepare E-chips for in situ/operando CCGR-STEM&#160;experiments. Preparing the gas cell for catalysis studies typically requires dispersion of the catalyst nanoparticles onto the E-chip either from a colloidal liquid suspension (Fi...

Watch this Scientific Journal Video about Performing In Situ Closed-Cell Gas Reactions in the Transmission Electron Microscope at JoVE.com

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

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

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

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

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3.8K Views.  Oak Ridge National Laboratory. Here, we present a protocol for performing in situ TEM closed-cell gas reaction experiments while detailing several commonly used sample preparation methods.

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

Revealing Dynamic Processes of Materials in Liquids Using Liquid Cell Transmission Electron Microscopy

The recent development for in situ transmission electron microscopy, which allows imaging through liquids with high spatial resolution, has attracted significant interests across the research fields of materials science, physics, chemistry and biology. The key enabling technology is a liquid cell. We fabricate liquid cells with thin viewing windows through a sequential microfabrication process, including silicon nitride membrane deposition, photolithographic patterning, wafer etching, cell bonding, etc. A liquid cell with the dimensions of a regular TEM grid can fit in any standard TEM sample holder. About 100 nanoliters reaction solution is loaded into the reservoirs and about 30 picoliters liquid is drawn into the viewing windows by capillary force. Subsequently, the cell is sealed and loaded into a microscope for in situ imaging. Inside the TEM, the electron beam goes through the thin liquid layer sandwiched between two silicon nitride membranes. Dynamic processes of nanoparticles in liquids, such as nucleation and growth of nanocrystals, diffusion and assembly of nanoparticles, etc., have been imaged in real time with sub-nanometer resolution. We have also applied this method to other research areas, e.g., imaging proteins in water. Liquid cell TEM is poised to play a major role in revealing dynamic processes of materials in their working environments. It may also bring high impact in the study of biological processes in their native environment.

We have developed a self-contained liquid cell, which allows imaging through liquids using a transmission electron microscope. Dynamic processes of nanoparticles in liquids can be revealed in real time with sub-nanometer resolution.

The recent development for in situ transmission electron microscopy, which allows imaging through liquids with high spatial resolution, has attracted ...

In Situ Time-dependent Dielectric Breakdown in the Transmission Electron Microscope: A Possibility to Understand the Failure Mechanism in Microelectronic Devices

The time-dependent dielectric breakdown (TDDB) in on-chip interconnect stacks is one of the most critical failure mechanisms for microelectronic devices. The aggressive scaling of feature sizes, both on devices and interconnects, leads to serious challenges to ensure the required product reliability. Standard reliability tests and post-mortem failure analysis provide only limited information about the physics of failure mechanisms and degradation kinetics. Therefore it is necessary to develop new experimental approaches and procedures to study the TDDB failure mechanisms and degradation kinetics in particular. In this paper, an in situ experimental methodology in the transmission electron microscope (TEM) is demonstrated to investigate the TDDB degradation and failure mechanisms in Cu/ULK interconnect stacks. High quality imaging and chemical analysis are used to study the kinetic process. The in situ electrical test is integrated into the TEM to provide an elevated electrical field to the dielectrics. Electron tomography is utilized to characterize the directed Cu diffusion in the insulating dielectrics. This experimental procedure opens a possibility to study the failure mechanism in interconnect stacks of microelectronic products, and it could also be extended to other structures in active devices.

In Situ Time-dependent Dielectric Breakdown in the Transmission Electron Microscope: A Possibility to Understand the Failure Mechanism in Microelectronic Devices

The time-dependent dielectric breakdown (TDDB) in on-chip interconnect stacks is one of the most critical failure mechanisms for microelectronic devices. This paper demonstrates the procedure of an in situ TDDB experiment in the transmission electron microscope, which opens a possibility to study the failure mechanism in microelectronic products.

The time-dependent dielectric breakdown (TDDB) in on-chip interconnect stacks is one of the most critical failure mechanisms for microelectronic devices. ...

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.

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

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.

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

Studying Dynamic Processes of Nano-sized Objects in Liquid using Scanning Transmission Electron Microscopy

Samples fully embedded in liquid can be studied at a nanoscale spatial resolution with Scanning Transmission Electron Microscopy (STEM) using a microfluidic chamber assembled in the specimen holder for Transmission Electron Microscopy (TEM) and STEM. The microfluidic system consists of two silicon microchips supporting thin Silicon Nitride (SiN) membrane windows. This article describes the basic steps of sample loading and data acquisition. Most important of all is to ensure that the liquid compartment is correctly assembled, thus providing a thin liquid layer and a vacuum seal. This protocol also includes a number of tests necessary to perform during sample loading in order to ensure correct assembly. Once the sample is loaded in the electron microscope, the liquid thickness needs to be measured. Incorrect assembly may result in a too-thick liquid, while a too-thin liquid may indicate the absence of liquid, such as when a bubble is formed. Finally, the protocol explains how images are taken and how dynamic processes can be studied. A sample containing AuNPs is imaged both in pure water and in saline.

This protocol describes the operation of a liquid flow specimen holder for scanning transmission electron microscopy of AuNPs in water, as used for the observation of nanoscale dynamic processes.

Samples fully embedded in liquid can be studied at a nanoscale spatial resolution with Scanning Transmission Electron Microscopy (STEM) using a ...

Characterization of Ultra-fine Grained and Nanocrystalline Materials Using Transmission Kikuchi Diffraction

One of the challenges in microstructure analysis nowadays resides in the reliable and accurate characterization of ultra-fine grained (UFG) and nanocrystalline materials. The traditional techniques associated with scanning electron microscopy (SEM), such as electron backscatter diffraction (EBSD), do not possess the required spatial resolution due to the large interaction volume between the electrons from the beam and the atoms of the material. Transmission electron microscopy (TEM) has the required spatial resolution. However, due to a lack of automation in the analysis system, the rate of data acquisition is slow which limits the area of the specimen that can be characterized. This paper presents a new characterization technique, Transmission Kikuchi Diffraction (TKD), which enables the analysis of the microstructure of UFG and nanocrystalline materials using an SEM equipped with a standard EBSD system. The spatial resolution of this technique can reach 2 nm. This technique can be applied to a large range of materials that would be difficult to analyze using traditional EBSD. After presenting the experimental set up and describing the different steps necessary to realize a TKD analysis, examples of its use on metal alloys and minerals are shown to illustrate the resolution of the technique and its flexibility in term of material to be characterized.

This paper provides a detailed method to characterize the microstructure of ultra-fine grained and nanocrystalline materials using a scanning electron microscope equipped with a standard electron backscatter diffraction system. Metal alloys and minerals presenting refined microstructures are analyzed using this technique, showing the diversity of its possible applications.

One of the challenges in microstructure analysis nowadays resides in the reliable and accurate characterization of ultra-fine grained (UFG) and ...

A Method for Obtaining Serial Ultrathin Sections of Microorganisms in Transmission Electron Microscopy

Observing cells and cell components in three dimensions at high magnification in transmission electron microscopy requires preparing serial ultrathin sections of the specimen. Although preparing serial ultrathin sections is considered to be very difficult, it is rather easy if the proper method is used. In this paper, we show a step-by-step procedure for safely obtaining serial ultrathin sections of microorganisms. The key points of this method are: 1) to use the large part of the specimen and adjust the specimen surface and knife edge so that they are parallel to each other; 2) to cut serial sections in groups and avoid difficulty in separating sections using a pair of hair strands when retrieving a group of serial sections onto the slit grids; 3) to use a 'Section-holding loop' and avoid mixing up the order of the section groups; 4) to use a 'Water-surface-raising loop' and make sure the sections are positioned on the apex of the water and that they touch the grid first, in order to place them in the desired position on the grids; 5) to use the support film on an aluminum rack and make it easier to recover the sections on the grids and to avoid wrinkling of the support film; and 6) to use a staining tube and avoid accidentally breaking the support films with tweezers. This new method enables obtaining serial ultrathin sections without difficulty. The method makes it possible to analyze cell structures of microorganisms at high resolution in 3D, which cannot be achieved by using the automatic tape-collecting ultramicrotome method and serial block-face or focused ion beam scanning electron microscopy.

This study presents reliable and easy procedures for obtaining serial ultrathin sections of a microorganism without expensive equipment in transmission electron microscopy.

Observing cells and cell components in three dimensions at high magnification in transmission electron microscopy requires preparing serial ultrathin ...

Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses

We demonstrate the use of two nuclear-based analytical methods that can follow the modifications of microstructural arrangement of iron-based metallic glasses (MGs). Despite their amorphous nature, the identification of hyperfine interactions unveils faint structural modifications. For this purpose, we have employed two techniques that utilize nuclear resonance among nuclear levels of a stable 57Fe isotope, namely M&#246;ssbauer spectrometry and nuclear forward scattering (NFS) of synchrotron radiation. The effects of heat treatment upon (Fe2.85Co1)77Mo8Cu1B14 MG are discussed using the results of ex situ and in situ experiments, respectively. As both methods are sensitive to hyperfine interactions, information on structural arrangement as well as on magnetic microstructure is readily available. M&#246;ssbauer spectrometry performed ex situ describes how the structural arrangement and magnetic microstructure appears at room temperature after the annealing under certain conditions (temperature, time), and thus this technique inspects steady states. On the other hand, NFS data are recorded in situ during dynamically changing temperature and NFS examines transient states. The use of both techniques provides complementary information. In general, they can be applied to any suitable system in which it is important to know its steady state but also transient states.

Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses

Here, we present a protocol to describe ex situ and in situ investigations of structural transformations in metallic glasses. We employed nuclear-based analytical methods which inspect hyperfine interactions. We demonstrate the applicability of M&#246;ssbauer spectrometry and nuclear forward scattering of synchrotron radiation during temperature-driven experiments.

We demonstrate the use of two nuclear-based analytical methods that can follow the modifications of microstructural arrangement of iron-based metallic ...

Scalable Quantum Integrated Circuits on Superconducting Two-Dimensional Electron Gas Platform

To form a coherent quantum transport in hybrid superconductor-semiconductor (S-Sm) junctions, the formation of a homogeneous and barrier-free interface between two different materials is necessary. The S-Sm junction with high interface transparency will then facilitate the observation of the induced hard superconducting gap, which is the key requirement to access the topological phases (TPs) and observation of exotic quasiparticles such as Majorana zero modes (MZM) in hybrid systems. A material platform that can support observation of TPs and allows the realization of complex and branched geometries is therefore highly demanding in quantum processing and computing science and technology. Here, we introduce a two-dimensional material system and study the proximity induced superconductivity in semiconducting two-dimensional electron gas (2DEG) that is the basis of a hybrid quantum integrated circuit (QIC). The 2DEG is a 30 nm thick In0.75Ga0.25As quantum well that is buried between two In0.75Al0.25As barriers in a heterostructure. Niobium (Nb) films are used as the superconducting electrodes to form Nb- In0.75Ga0.25As -Nb Josephson junctions (JJs) that are symmetric, planar and ballistic. Two different approaches were used to form the JJs and QICs. The long junctions were fabricated photolithographically, but e-beam lithography was used for short junctions&#8217; fabrication. The coherent quantum transport measurements as a function of temperature in the presence/absence of magnetic field B are discussed. In both device fabrication approaches, the proximity induced superconducting properties were observed in the In0.75Ga0.25As 2DEG. It was found that e-beam lithographically patterned JJs of shorter lengths result in observation of induced superconducting gap at much higher temperature ranges. The results that are reproducible and clean suggesting that the hybrid 2D JJs and QICs based on In0.75Ga0.25As quantum wells could be a promising material platform to realize the real complex and scalable electronic and photonic quantum circuitry and devices.

Quantum integrated circuits (QICs) consisting of array of planar and ballistic Josephson junctions (JJs) based on In0.75Ga0.25As two-dimensional electron gas (2DEG) is demonstrated. Two different methods for fabrication of the two-dimensional (2D) JJs and QICs are discussed followed by the demonstration of quantum transport measurements in sub-Kelvin temperatures.

To form a coherent quantum transport in hybrid superconductor-semiconductor (S-Sm) junctions, the formation of a homogeneous and barrier-free interface ...

Single-Digit Nanometer Electron-Beam Lithography with an Aberration-Corrected Scanning Transmission Electron Microscope

We demonstrate extension of electron-beam lithography using conventional resists and pattern transfer processes to single-digit nanometer dimensions by employing an aberration-corrected scanning transmission electron microscope as the exposure tool. Here, we present results of single-digit nanometer patterning of two widely used electron-beam resists: poly (methyl methacrylate) and hydrogen silsesquioxane. The method achieves sub-5 nanometer features in poly (methyl methacrylate) and sub-10 nanometer resolution in hydrogen silsesquioxane. High-fidelity transfer of these patterns into target materials of choice can be performed using metal lift-off, plasma etch, and resist infiltration with organometallics.

We use an aberration-corrected scanning transmission electron microscope to define single-digit nanometer patterns in two widely-used electron-beam resists: poly (methyl methacrylate) and hydrogen silsesquioxane. Resist patterns can be replicated in target materials of choice with single-digit nanometer fidelity using liftoff, plasma etching, and resist infiltration by organometallics.

We demonstrate extension of electron-beam lithography using conventional resists and pattern transfer processes to single-digit nanometer dimensions by ...