The upcoming Microscopy & Microanalysis 2011 meeting in Nashville will include the world's largest annual exhibition of microscope equipment, supplies, and services. For most attendees, the exhibition is one of the highlights of the M&M meeting.

Light optical imaging techniques that don't require labels are attractive for human studies because they are not toxic nor do they perturb the system being studied. Whereas there are several methods available to provide microscopic imaging below the surface of a tissue, they each suffer from limitations, such as low spatiotemporal resolution and a limited number of molecular signatures that can be imaged. Raman spectroscopy offers label-free contrast for major chemical species in tissue, such as water, lipids, DNA, and proteins based on vibrational spectra at light optical wavelengths. However, the Raman signal is very weak, which makes it difficult to image a sample with good temporal resolution. The recent development of stimulated Raman scattering (SRS) microscopy can overcome these limitations as demonstrated by the elegant studies of Brian Saar, Christian Freudiger, Jay Reichman, Michael Stanley, Gary Holton, and Sunney Xie. Saar et al. improved the optics and electronics for the acquisition of the backscattered signal of SRS. In SRS microscopy, the sample is excited by two lasers at different frequencies. When the difference in frequency matches a molecular vibration in the sample, the intensities of the probes change in a predictable manner. These intensity changes are small, but Saar et al. developed a new method to detect them. They chopped one of the laser beams at high frequency (MHz) and detected the intensity change in the other beam, which offered superior sensitivity. The key component was a custom-made all-analog lock-in amplifier with a very short (about 100 ns) response time. The laser probe wavelengths were tuned to match a vibrational frequency of interest and raster-scanned across the sample. Frequencies were tuned to detect CH2 stretching (primarily for lipids), OH stretching (primarily water), and CH3 stretching (primarily proteins) vibrations. Imaging of water is of particular interest in studying the transport of water-soluble compounds such as drugs.

In his now-famous 1959 speech on nanotechnology, Richard Feynman proposed that it should be possible to see the individual atoms in a material, if only the electron microscope could be made 100 times better. With the development of aberration correctors on transmission electron microscopes (TEMs) over the last decade, this dream of microscopists to directly image structures atom-by-atom has come close to an everyday reality. Figure 1 shows such a high-resolution transmission electron microscope (HR-TEM) image of a single-wall carbon nanotube obtained with an aberration-corrected TEM. Now that atomic-resolution images have become possible with aberration-corrector technology in both TEM and STEM, we can ask ourselves if we truly have achieved the goal of seeing individual atoms. Most aberration-corrected images exhibiting atomic resolution are not distinguishing individual atoms, but columns of a small number of atoms, so despite this remarkable achievement, there is still “plenty of room at the bottom” in order to move toward seeing, counting, and quantifying individual atoms. In fact, there never has been a more exciting time for electron microscopists.

Solid materials in subambient gaseous environments have been imaged using in situ transmission electron microscopy (TEM), for example to study dynamic effects: carbon nanotube growth, nanoparticle changes during redox reactions, and phase transitions in nanoscale systems. In these studies the vacuum level in the specimen region of the electron microscope was increased to pressures of up to 10 mbar using pump-limiting apertures that separated the specimen region from the rest of the high-vacuum electron column, but it has not been possible to achieve the higher pressures that are desirable for catalysis research. TEM imaging at atmospheric pressure and at elevated temperature was achieved with 0.2-nm resolution by enclosing a gaseous environment several micrometers thick between ultra-thin, electron transparent silicon nitride windows. Although Ångström-level resolution in situ TEM has been demonstrated with aberration-corrected systems, the key difficulty with TEM imaging is its dependence on phase contrast, which requires ultra-thin specimens, limiting the choice of experiments.

Charged particle microscopes have been used extensively for the creation of nanostructures. As a subset of the techniques for this, the process of beam-induced chemistry offers almost endless flexibility for both additive (by beam-driven precursor deposition) and subtractive (by beam-catalyzed etching) processing. A recent review article makes it evident simply by its massive page count the number of materials that have been used to deposit a variety of conductive, insulating, magnetic, photonic, and other structures. To take advantage of these capabilities, though, the nanoarchitect must select the correct settings for a large number of parameters. One key figure of interest is the size of features that can be written by deposition of conducting material: how small can we go? Process development is complex, however: a standard beam-induced deposition process using the system described below calls for the control of sixteen different parameters! Several of these are used to set the flow of the reactant, several are required for defining the particle beam, and yet another set of parameters call out the routine by which the beam is scanned over the pattern of interest. In the end, the result provides just one recipe for one chemistry with one beam type. The wide scatter of reported outcomes in the review article mentioned above indicates the complexity of the problem, where each result given can be considered just a snapshot of one small corner of the parameter space. Our goal here is to apply a quantitative optimization methodology for the determination of beam chemistry processes in the helium ion microscope (HIM). In this article, we discuss efforts toward finding the minimum obtainable line width and gap width between line pairs of deposited platinum lines and giving a predictive formulation of the same.

The performance metric of greatest interest to the user of a focused ion beam (FIB) system is generally its resolution. Because of the difficulty in defining and measuring the resolution of a FIB system directly, its performance is often assessed using a method related to the beam quality instead. This consists of the measurement of the rise distance of the beam current as the beam passes across an edge, which, for low currents where spherical aberration can be neglected, is closely related to the full width at half maximum (FWHM) of the current density of the ion beam. The edge, also known as the “knife edge,” corresponds to a sharp discontinuity in a specimen, as can be practically found on the surface of a graphite specimen. Because the rise distance can be used to obtain an idea of the dimension of the waist of a beam, it is, perhaps, an indication of the quality of an instrument. Because the rise distance depends on the quality of an edge, it is sometimes called edge sharpness. This concept bears similarities with the image sharpness method developed to assess the performance of SEMs, usually on gold nanoparticles on carbon specimen. Rise distance is actually a convolution of the current density distribution with the properties of the knife edge and depends strongly on the spatial distribution of the secondary electron yield of the edge. By using the rise distance, different systems can be compared in a quantitative way. To compare instruments, the identical specimen must be used and the measurements must be done in an identical way. This article discusses the method and some pitfalls in its application.

The previous article in this series introduced DTSA-II and provided some background information including how to configure DTSA-II for your x-ray detector and how to read spectra from disk. This article presents more basic background material. It discusses how to display and perform basic manipulations on spectra including reading the contextual properties of spectra, visualizing spectra, labeling characteristic x-ray lines, and exporting the results as publication-quality graphics. You are encouraged to follow along using DTSA-II and example spectra, which may be downloaded for free from http://www.cstl.nist.gov/div837/837.02/epq/dtsa2/index.html or equivalently http://goo.gl/MI1Ku. With this background material, we will be ready to consider more sophisticated tasks like spectrum quantification and simulation in upcoming articles.

The development of large-area silicon drift detectors (SDDs) provides a significant improvement in X-ray micro-analysis, especially in scanning electron microscopes (SEMs) and electron microprobes, where high incident probe currents are possible. The resultant improved detection limits and/or speed of elemental mapping and analysis make the SDD the detector of choice for microanalysis. With the larger geometric collection efficiency and faster response times of these detectors, the higher input count rates can place significant demands on the performance and speed of the signal processing electronics.

In his 2011 State of the Union address, President Barack Obama echoed the sentiments of this nation's leaders for the past twenty years when he stated, “Nations like China and India realized…they could compete in this new world. So they started educating their children earlier and longer, with greater emphasis on math and science. They're investing in research and new technologies…. Maintaining our leadership in research and technology is crucial to America's success. But if we want to win the future—if we want innovation to produce jobs in America and not overseas—then we also have to win the race to educate our kids.” The Bergen County Academies (BCA) in Hackensack, NJ, is attempting to do just that: invest in research and technology at the high school level in order to expose students to real world opportunities and applications they will experience in the future.

Though microscopes and telescopes had been invented in the late sixteenth century, various optical difficulties meant that the devices were more commonly considered novelties than useful scientific instruments for many years. Chief among these problems were aberrations in the images caused by optical errors from the lenses. Many scientists had attempted to rectify such difficulties, but the nineteenth-century amateur microscopist Joseph Jackson Lister is credited with making some of the most important advances toward correcting image aberrations and establishing the microscope as a powerful means of carrying out serious scientific investigations.

Selected postings from the Microscopy Listserver from January 1, 2011 to March 2, 2011. Complete listings and subscription information can be obtained at http://www.microscopy.com. Postings may have been edited to conserve space or for clarity.

I write this as a materials scientist concerned about the inadequacy of regulation, monitoring, and control of what are known as nanoparticles (NPs). This is not because present particulate legislation is “inadequate” but because it is inadequately policed and does NOT extend to small enough particulates. I have analyzed these very small particles in the analytical electron microscope (AEM) for over thirty-seven years. A graduate student, with whom I worked over thirty years ago, described in her thesis the conclusion that these particles would have “long-range environmental impact.” We did not then have the benefit of hindsight.