2.6.2 Electrodes for Electrochemistry

The first book on the topic, with each chapter written by pioneers in the field, this essential resource details the fundamental theory, applications, and future developments of liquid cell electron microscopy. This book describes the techniques that have been developed to image liquids in both transmission and scanning electron microscopes, including general strategies for examining liquids, closed and open cell electron microscopy, experimental design, resolution, and electron beam effects. A wealth of practical guidance is provided, and applications are described in areas such as electrochemistry, corrosion and batteries, nanocrystal growth, biomineralization, biomaterials and biological processes, beam-induced processing, and fluid physics. The book also looks ahead to the future development of the technique, discussing technical advances that will enable higher resolution, analytical microscopy, and even holography of liquid samples. This is essential reading for researchers and practitioners alike.

A guide to modern scanning electron microscopy instrumentation, methodology and techniques, highlighting novel applications to cell and molecular biology.

The advent of the electron microscope has fostered major advances in a broad spectrum of disciplines. The required vacuum environment of standard electron microscopy, however, precludes imaging of systems containing high vapor pressure liquids. The recent development of liquid cells like the Penn nanoaquarium overcomes this limitation, enabling imaging of temporally evolving processes in liquids with nanoscale resolution at video frame rates. We used Liquid Cell Electron Microscopy to investigate the morphological evolution of the electrode-electrolyte interface during electroplating, the onset of diffusive instabilities in electrodeposits, beam-mediated nucleation, growth, and dissolution of metallic nanoparticles, the nucleation and growth of nanobubbles, and the fundamentals of the electron-water interactions (Radiation Chemistry). The control of interfacial morphology in electrochemical processes is essential for applications ranging from nanomanufacturing to battery technologies. Critical questions still remain in understanding the transition between various growth regimes, particularly the onset of diffusion-limited growth. We present quantitative observations at previously unexplored length and time scales that clarify the evolution of the metal-electrolyte interface during deposition. The interface evolution during initial stages of galvanostatic Cu deposition on Pt from an acidic electrolyte is consistent with kinetic roughening theory, while at later times the behavior is consistent with diffusion limited growth physics. To control morphology, we demonstrate rapid pulse plating without entering the diffusion-limited regime, and study the effects of the inorganic additive Pb on the growth habit. The irradiating electrons used for imaging, however, affect the chemistry of the suspending medium. The electron beam's interaction with the water solvent produces molecular and radical products such as hydrogen, oxygen, and hydrated (solvated) electrons. A detailed understanding of the interactions between the electrons and the irradiated medium is necessary to correctly interpret experiments, minimize artifacts, and take advantage of the irradiation as a tool. We predict the composition of water subjected to electron irradiation under conditions relevant to liquid cell electron microscopy. We interpret experimental data, such as beam-induced colloid aggregation and observations of crystallization and etching of metallic particles as functions of dose rate. Our predictive model is useful for designing experiments that minimize unwanted solution chemistry effects, extend liquid cell microscopy to new applications, take advantage of beam effects for nanomanufacturing such as the patterning of nanostructures, and properly interpreting experimental observations.

This concise reference summarizes the latest results in nano-structured thin films, the first to discuss both deposition methods and electronic applications in detail. Following an introduction to this rapidly developing field, the authors present a variety of organic and inorganic materials along with new deposition techniques, and conclude with an overview of applications and considerations for their technology deployment.

This text is a companion volume to Transmission Electron Microscopy: A Textbook for Materials Science by Williams and Carter. The aim is to extend the discussion of certain topics that are either rapidly changing at this time or that would benefit from more detailed discussion than space allowed in the primary text. World-renowned researchers have contributed chapters in their area of expertise, and the editors have carefully prepared these chapters to provide a uniform tone and treatment for this exciting material. The book features an unparalleled collection of color figures showcasing the quality and variety of chemical data that can be obtained from today’s instruments, as well as key pitfalls to avoid. As with the previous TEM text, each chapter contains two sets of questions, one for self assessment and a second more suitable for homework assignments. Throughout the book, the style follows that of Williams & Carter even when the subject matter becomes challenging—the aim is always to make the topic understandable by first-year graduate students and others who are working in the field of Materials Science Topics covered include sources, in-situ experiments, electron diffraction, Digital Micrograph, waves and holography, focal-series reconstruction and direct methods, STEM and tomography, energy-filtered TEM (EFTEM) imaging, and spectrum imaging. The range and depth of material makes this companion volume essential reading for the budding microscopist and a key reference for practicing researchers using these and related techniques.

To preserve tissue by freezing is an ancient concept going back pre sumably to the practice of ice-age hunters. At first glance, it seems as simple as it is attractive: the dynamics of life are frozen in, nothing is added and nothing withdrawn except thermal energy. Thus, the result should be more life-like than after poisoning, tan ning and drying a living cell as we may rudely call the conventional preparation of specimens for electron microscopy. Countless mishaps, however, have taught electron microscopists that cryotechniques too are neither simple nor necessarily more life-like in their outcome. Not too long ago, experts in cryotechniques strictly denied that a cell could truly be vitrified, i.e. that all the solutes and macro molecules could be fixed within non-crystalline, glass-like solid water without the dramatic shifts and segregation effects caused by crystallization. We now know that vitrification is indeed pos sible. Growing insight into the fundamentals of the physics of water and ice, as well as increasing experience of how to cool cells rapidly enough have enlivened the interest in cryofixation and pro duced a wealth of successful applications.

Scanning electr on microscopy (SEM) and x-ray microanalysis can produce magnified images and in situ chemical information from virtually any type of specimen. The two instruments generally operate in a high vacuum and a very dry environment in order to produce the high energy beam of electrons needed for imaging and analysis. With a few notable exceptions, most specimens destined for study in the SEM are poor conductors and composed of beam sensitive light elements containing variable amounts of water. In the SEM, the imaging system depends on the specimen being sufficiently electrically conductive to ensure that the bulk of the incoming electrons go to ground. The formation of the image depends on collecting the different signals that are scattered as a consequence of the high energy beam interacting with the sample. Backscattered electrons and secondary electrons are generated within the primary beam-sample interactive volume and are the two principal signals used to form images. The backscattered electron coefficient ( ? ) increases with increasing atomic number of the specimen, whereas the secondary electron coefficient ( ? ) is relatively insensitive to atomic number. This fundamental diff- ence in the two signals can have an important effect on the way samples may need to be prepared. The analytical system depends on collecting the x-ray photons that are generated within the sample as a consequence of interaction with the same high energy beam of primary electrons used to produce images.

Adopting a didactical approach from fundamentals to actual experiments and applications, this handbook and ready reference covers real-time observations using modern scanning electron microscopy and transmission electron microscopy, while also providing information on the required stages and samples. The text begins with introductory material and the basics, before describing advancements and applications in dynamic transmission electron microscopy and reflection electron microscopy. Subsequently, the techniques needed to determine growth processes, chemical reactions and oxidation, irradiation effects, mechanical, magnetic, and ferroelectric properties as well as cathodoluminiscence and electromigration are discussed.

Electron microscopy has revolutionized our understanding the extraordinary intellectual demands required of the mi of materials by completing the processing-structure-prop croscopist in order to do the job properly: crystallography, erties links down to atomistic levels. It now is even possible diffraction, image contrast, inelastic scattering events, and to tailor the microstructure (and meso structure ) of materials spectroscopy. Remember, these used to be fields in them to achieve specific sets of properties; the extraordinary abili selves. Today, one has to understand the fundamentals ties of modem transmission electron microscopy-TEM of all of these areas before one can hope to tackle signifi instruments to provide almost all of the structural, phase, cant problems in materials science. TEM is a technique of and crystallographic data allow us to accomplish this feat. characterizing materials down to the atomic limits. It must Therefore, it is obvious that any curriculum in modem mate be used with care and attention, in many cases involving rials education must include suitable courses in electron mi teams of experts from different venues. The fundamentals croscopy. It is also essential that suitable texts be available are, of course, based in physics, so aspiring materials sci for the preparation of the students and researchers who must entists would be well advised to have prior exposure to, for carry out electron microscopy properly and quantitatively.