The observation of microstructural features smaller than 300 nm is generally performed using Transmission Electron Microscopy (TEM) because conventional Scanning Electron Microscopes (SEM) do not have the resolution to image such small phases. Since the early 1990’s, a new generation of microscopes is now available on the market. These are the Field Emission Gun Scanning Electron Microscope with a virtual secondary electron detector. The field emission gun gives a higher brightness than those obtained using conventional electron filaments allowing enough electrons to be collected to operate the microscope with incident electron energy, E0, below 5 keV, with probe diameter smaller than 2.5 nm. Furthermore, what gives FE-SEM outstanding resolution is the combination of new magnetic lenses with a virtual secondary electron (SE) detector. The new lenses are designed to reduce the spherical and chromatic aberration coefficients, giving a smaller probe size. Contrary to the conventional systems, the SE detector is located above the objective lens and it becomes a virtual or through-the-lens (TTL) detector. Therefore, the SE image is mostly made up of all SEs of type I, almost eliminating those of type II and III which are generated by the backscattered electrons inside the specimen as well as in the chamber. It has been shown recently that Nb(CN) precipitates in Fe, as small than 10 nm, can be imaged with a FE-SEM Hitachi S-4500 with the TTL detector.

Conventionally, x-ray microanalysis on scanning electron microscopes (SEM) with energy dispersive spectrometers (EDS) has been performed with relatively high primary energies (>10 kv). for most samples this results in reasonably good separation of the generated x-ray line series from different elements enabling unambiguous identification and therefore accurate qualitative analysis. Under these circumstances it is widely accepted that quantitative analysis of polished bulk samples is possible on a routine basis with relative errors around 1-5% and detection limits of the order of 0.1%.

However, in order to address the analysis requirements of new advanced materials with sub-micron features, there is growing interest in performing x-ray microanalysis at low beam energies(<5kv). this is now a more realistic goal due to the routine availability of field emission sem's which can operate with much improved beam sizes at low beam energies with sufficient beam current to perform practical microanalysis, in conjunction with the improved low energy performance of current, commercially available EDS systems.

An earlier investigation had shown that it is possible to perform quantitative energy dispersive x-ray microanalysis at primary beam voltages as low as 5kV on bulk biological material maintained in either the fully frozen hydrated or the dried state. This present study extends the earlier work and provides data which shows that the same type of analysis can be achieved at voltages as low as 3kV on organic samples composed primarily of hydrogen, carbon and oxygen which contain varying amounts of bromine, sulphur and chlorine. Such materials are equally beam sensitive as fully frozen hydrated biological samples and range in density from 1.1 to 2.2kg.m3. The samples fall into three main classes. 1. Chlorinated and/or sulphonated organic polymers. 2. A brominated organic sample. 3. Three experimental brominated plastics kindly supplied by Ms. B.S.Chuah, Melville Laboratory for Polymer Synthesis, Cambridge University. The remaining samples were purchased from Aldrich Chemicals at the highest purity available. The atomic weight percent and density was calculated for each of the eight specimens using the Electron Flight Simulation™ software programme.

The need to analyze bulk samples containing features with submicron dimensions has driven revaluation of the processes controlling the interaction of electron beams with inorganic, polymer and semiconductor materials, and to development of LVEDS analysis at lower beam energies of E0 <5kV (1,2).

It has previously been shown (1,2) that the physics is much as expected with the vertical penetration range (R) along the beam direction in many cases predicted quite accurately for beam energy E0 by the simple Bethe (e.g. in 3) power law with R = F(E0)5/3. These same factors are effective to varying degrees in all three dimensions. The strong dependence of the range on energy has practical importance for the identification of sub-micron particles, including to help to determine the root cause of a defect Fig. 1 is an example of the sequential analysis of the exact same sub-micron particle, with the very real potential for a processing disaster, on the surface of a silicon wafer. When this feature is analyzed with a 3kV electron beam we learn it is alumina (A12O3). The analysis comes only from the target particle and the data have a simple relationship to the chemistry and the sensitivity for the light element (O) is excellent, providing simple and direct qualitative identification of the oxide compound.

It has been shown recently that precipitates as small as 10 nm can be imaged with a FE-SEM using a Through-The-Lens (TTL) SE detector or the so-called Upper Detector (UD). This is a very significant finding because normally, such small precipitates are observed in the TEM where specimen preparation techniques are generally a timely process. However, from Monte Carlo simulations using CASINO, it has been shown that NbC precipitates embedded in Fe as small than 6 nm can be imaged with BE. The experimental demonstration was difficult because no good BSE detectors were available at that time for low energy work.

Recently, a new BSE detector has been developed for low energy work from the GW corporation, the Centaurus BSE detector. This detector is coupled with an HITACHI S-4700 FESEM In this work, images of Mg2Zn precipitates in Al obtained with the UD and the Centaurus BSE detector are compared.

One of the advantages of performing X-ray microanalysis at low (≤5 kV) operating voltages is that high spatial resolution (≤250 nm) chemical maps of the specimen can be acquired. Spectrum imaging, where a full spectrum is acquired for each pixel in a two-dimensional array, provides the most comprehensive method of characterization, as long as the sampling density (pixel size) is sufficiently smaller than the spatial resolution. Multivariate statistical analysis (MSA) methods are effective in reducing the large (typically ∼10 MByte) raw spectrum images to the modest (typically ∼100 kByte) data files that contain all of the statistically significant information of interest about the specimen. Preliminary analysis of a cross section of a computer chip from a major semiconductor company was previously performed using limited spectrum imaging capabilities available with the 4pi X-ray mapping module, which allowed for simultaneous acquisition of only 48 channels. MSA of images acquired with only a 960 eV portion of the spectrum containing the Al-K, Si-K and W-M lines showed that excellent contrast between the Si- and W-rich regions of the specimen could be achieved in spite of the strong overlap between Si-Kα and W-Mα (∼34 eV separation).

Telemicroscopy, sometimes called remote microscopy, is an expanding set of microscopy techniques, made possible by the advent of ubiquitous and pervasive Internet technologies such as the World Wide Web. Recently, telemicroscopy has moved from laboratory prototypes to commercially available software. This paper discusses a real-world application of telemicroscopy in terms of a microscopy consultancy service offered by ERA Technology Ltd. in Leatherhead, UK.

Many organisations require microscopical services on an occasional basis. These needs are not however, sufficiently frequent as to justify the purchase and upkeep of an SEM or the recruitment and retention of a trained instrument operator Such organisations employ consultancy firms to perform the required analyses. In many such consultancies, a sample is sent to the microscopist with appropriate instructions. Once the investigation is complete, the consultant returns sample, micrographs and other results. The SEM service run by ERA has always offered its customers the opportunity for personal participation in any investigation, by attendance at SEM sessions at the Leatherhead laboratory.

Miniaturization of electron optical systems has gained much interest over the last decade [1,2]. In a scanning electron microscope, downscaling of the column dimensions is expected to allow for high resolution imaging at low electron beam voltage. Main advantages of low voltage imaging are lower penetration depth, increased secondary electron yield, less specimen charging and better topographic contrast [3].

We have developed a miniature scanning electron microscope (SEM) with high resolution at low beam energies. The outer dimensions of the miniaturized SEM column are 25 mm diameter and 95 mm length, including conventional field emitter electron source module. The column prototype is shown in Fig. 1. The size reduction has been achieved by the exclusive implementation of electrostatic column components. Electron optical simulations indicate that the retarding objective lens of the miniature SEM allows for a probe resolution of 3 nm at 1 keV beam energy. The secondary electrons are collected at an internal scintillator detector.

Self-assembled monolayers (SAM) and multilayers of organic materials have been intensely studied in the past years, due to their numerous potential applications as, for example, lubricants, corrosioninhibitors and/or adhesion-promoters [1,2]. Due to the reduced height of SAM, typically a couple of nanometers, the various Scanning Probe Microscopy (SPM) techniques, especially Scanning Tunneling Microscopy (STM) and Atomic Force Microscopy (AFM), have been the tools of choice in the morphological and structural study of those systems [1,2]. However, these SPM techniques have some limitations. One of them is the reduced scanning area, preventing the assessment of SAM coverage in large substrate areas, which is one of the key issues in studies of the potential applicability of SAM. Furthermore, due to their imaging principle, the SPM techniques are not suited to analyze SAM on substrates where the roughness is of the order of hundreds of nanometers or higher, impeding their application on most non-ideal (atomically flat) substrates.

Recently studies examining the colonization of Clostridial pathogens on agar and human tissue culture cells, demonstrated that (C. sporogenes ATCC 3584, C. difficile ATCC 43594 [patient isolate], C. difficile ATCC 9689 [non-clinical], C. clostridioforme [patient isolate]) bacterial spores (endospores) of the genus Clostridia have an outer membrane that becomes responsive at activation and exhibits extensions of the exosporial membrane that facilitate and maintain spore attachment to a nutritive substrate during germination and initial outgrowth of the newly developed bacterial cell. Therefore this attachment phenomenon plays an important role in insuring bacterial colonization of a surface and the initial stages of the infective process. To see if other non-clinical members of this genus also have this ability to attach to a substrate or food-source during spore germination, and how this attachment process in environmental thermophiles compares to the clinical paradigm (in relation to time sequence, exosporial membrane structure, type of attachment structures, composition of the membrane etc.), sediment samples were collected in sterile transport containers at 4 geothermal sites at Yellowstone National Park in Wyoming.

Research into bone histology of fossil material is a growing area of inquiry in vertebrate paleontology. Incorporating histological study into ontogenetic investigation presents new opportunities for gaining data to better understand ontogeny, ecology, and evolution of mosasaurs. Adding scanning electron microscopy to the growing technology being applied to fossil research can only further the understanding of long extinct animals.

Mosasaurs were totally marine lizards which inhabited both open ocean and epicontinental seas during the late Cretaceous (Turonian through Maestrichtian), approximately 90-65. million years ago. Mosasaurs have been collected from many areas of North America. The specimens used in this study were collected from Alabama, Kansas, South Dakota, and Texas. I have restricted the fossil material for destructive analysis to ribs and vertebrae. Ribs have not been shown to have importance in morphological analysis relating to systematics or evolution, therefore their destruction does not imped the research of others. Vertebrae were isolated on outcrop but could be identified to genus and growth stage.

The catalytic activity and selectivity of nanosize colloidal platinum (Pt) nanocrystals may depend strongly on their sizes and shapes. To determine the shape dependent catalytic behavior of Pt nanocrystals, two key steps are involved. First, shape controlled Pt nanocrystals must be synthesized at a high yield. Secondly, the passivation layer on the nanocrystal must be removed in order to measure the catalytic selectivity and activity while the particle shape is preserved. The former had been successfully demonstrated by us that platinum nanoparticles with a high percentage of cubic-, tetrahedral- and octahedral-like shapes, respectively, can be synthesized by a colloidal chemistry method [1,2]. The growth of the shape controlled Pt nanocrystal has been found to be the result of kinetic process [3]. To measure the shape dependent catalytic activity and selectivity of the Pt nanocrystals, the capping polymer must be removed. One method could be annealing the nanocrystals supported on a substrate for evaporating the capping polymer. Several questions, however, must be considered: (1) how high does the annealing temperature need to be to remove the capping polymer while the particle shape is still preserved? (2) to what temperature is the particle shape still stable? (3) is there a temperature induced shape transformation due to surface diffusion? (4) how high is the melting point of the Pt particles? and (5) what is the effect of substrate on nanoparticle melting? These questions have not only fundamental importance, but also practical impact on the catalysis applications of the particles because the chemical reaction may take place at a higher temperature.

Scanning Electron Microscopy (SEM) of thin film magnetic disk defects is challenging due to lubricant on the disk surface. The lubricant aids disk durability but interacts with the electron beam to form a contaminantation layer over the area of interest. A new cleaning technology allows the removal of the surface contamination while the specimen is in the SEM.

Plasma dry ashing of SEM samples to remove surface hydrocarbons is a well-known technique for specimen preparation. A number of commercial external plasma cleaning units are on the market for sample preparation outside the microscope. Zaluzec developed a technique for plasma cleaning the specimen and stage together prior to insertion into the analytical region of the electron microscope. But similar plasma cleaning within the SEM chamber must be avoided due to ion bombardment damage to the SEM and the deleterious effect of argon plasmas on ion pumps. XEI Scientific has developed a new device that creates neutral oxygen radicals from air. This technique oxidizes surface hydrocarbons into volatile gases that are easily carried away to the roughing and diffusion pumps.

We have developed a technique for measuring small strains during in-situ tensile tests in a Scanning Electron Microscope (SEM). The technique uses pattern recognition algorithms to locate markers on a gridded sample before and after deformation. The distortions in the grid are used to calculate the strains at each of the markers. The strains are then displayed in contour plots and correlated with the microstructure of the sample to help understand the local progression of strain as a function of applied load and microstructure.

Tensile experiments were performed on gridded notched and unnotched samples of a Ti-48Al-2Cr- 2Nb alloy (at%) in a Philips XL-30 FEGSEM using a 10,000 N Kamrath-Weiss in-situ straining stage. Gold was evaporated onto the samples through nickel grids with a mesh size of 17 μm. Electron backscatter images of the samples taken during testing were analyzed using a set of, interactive routines written in the Interactive Data Language (IDL).

A detailed understanding of phase transformation mechanisms in small particles is critical for the design of small metal particle catalysts and nanophase materials. For palladium supported on silica, it is known that under certain conditions, reduction of PdO can lead to the formation of small Pd metal particles containing central faceted voids[l]. In-situ microscopy studies show that the voids form when PdO is reduced at temperatures between 200 and 400°C but collapse when the temperature reaches about 550°C [2]. Here we present in-situ high resolution microscopy showing the details of the void formation process.

Model Pd/SiO2, catalysts were prepared by dispersing Pd metal over silica microspheres using techniques described elsewheretl]. The Pd/SiO2, catalyst were fully oxidize°C for 2 hours. The catalyst was crushed and dispersed over Mo grids and plasma cleaned to remove any residual carbonaceous material. A Philips CM 200 with a slow scan CCD camera and video recording system was used to recording HREM images during in situ reduction at 200°C.

The abilities of researchers to obtain high-quality images and other data from pin-mounted museum insect specimens using conventional scanning electron microscopy (SEM) are hindered by several necessary constraints. The specimens may represent unique exemplars (e.g., holotypes) upon which the taxon name rests. In some cases the specimen may no longer be extant in any environment outside the museum. Thus these insects must always be handled with extreme care,Tegardless of how they are to be observed.

Normal preparation of an insect for SEM involves sputter coating it with a conductive metal to minimize the effects of charging, and conductive paint must be applied to an obscure or uninteresting area to complete the connection to the specimen mount and thus to ground. Generally, unless such specimens have been newly collected, they will have already been killed and allowed to air dry, with a mounting pin inserted through the thorax. The body of the insect shrinks against the pin, which cannot then be removed for observation and later reinserted without damage.

In recent years the assembly of nanometer sized building blocks into two- and three-dimentional structures and functional materials has been an extremely active area of scientific research. A new class of materials, the DNA/nanoparticle hybrid materials and assemblies, which might have useful electrical, optical and structural properties, have been developed at Northwestern University. While characterizing particle morphology (size and shape) by subjecting it to the high vacuum environment in an electron microscope, the structure may have changed drastically from its natural state. The study of morphology of these DNA/Au nanoparticles in the liquid state was thus undertaken to further our understanding of the dynamics of the nanoparticles in a specific environment. This paper presents an in-situ observation of DNA/Au nanoparticle assembles in liquid media using environmental TEM.

Experiments were carried out with citrate-stabilized colloidal Au particles averaging 8 and 31 nm in diameter. Colloidal Au nanoparticles were obtained from a commercial source. 8 nm particles were modified with propylthiol-capped oligonucleotide, 3’HS(CH2)3-O(O)P(O)O-ATG-CTC-AAC-TCT, 1,whereas the 31 nm particles were modified with hexlylthiol-capped oligonucleotide, 3’TAG-GAC-TTA-CGC-O(O)P(O )O-(CH2)6SH, 2.

Decreasing dimensions and the necessity to understand the structure and composition of materials or devices on a nanometer scale has led to new developments in TEM. Previously EDX analysis had been established as the only analytical technique. In recent years the analytical capabilities of TEM have been augmented with a number of analytical techniques - such as electron energy-loss spectroscopy (EELS), electron holography, Lorentz microscopy, high-angle annular dark-field (HAADF). These have been developed or extended to yet unavailable levels of resolution. The Schottky field-emitters provide stable, reliable, coherent and high-current electron sources that are needed to get the best out of the mentioned analytical techniques.

The development of these analytical capabilities has been a parallel process in many different places and mainly led to dedicated microscopes optimized for one purpose only. This made it almost impossible to get different sets of analytical information from one specimen area simultaneously, and often the data even had to be collected from different specimens.

A new omega filter has successfully been installed in 200kV TEMs(see FIG. 1). Energy filtering TEM (EFTEM) is extremely useful to enhance contrast of biological specimens, to observe defects in thick semiconductor tips, to obtain a good compositional map in grain boundaries, to give structure image in the thick specimen regions and to obtain quantitative data by removing plasmon loss signals. In-column filters such as omega filter has advantages over postcolumn filters from points of cancellation of aberrations, to obtain iso-chromatic images and a freedom of selecting variety of magnifications.

Here, we discuss conditions of designing an omega filter. In usually, curved axis systems, which are common to energy analysis equipment, has large second order aberrations. Those aberrations are compensated in analyzers with single sector magnet with multi stage sextupole correctors. However, the adjustment of those correctors is difficult and residual aberrations destroy quality of the filtered image.

We have recently replaced the electron energy filter of the Zeiss EM 902 with an improved PMP filter. The design, incorporating concave curved entrance and exit faces and convex curves on the side facing the electrostatic mirror was based on the theoretical calculations of Jiang and Ottensmeyer and Barfels et al. Care was taken in the design of the filter to allow its introduction into the existing geometry of the microscope and its use of the existing electronics. As a result, dismantling the existing prism housing and support (which were used as the base for the new prism), reinstallation, and adjustment required only three working days. The resolution in tjie energy dispersive plane of the new filter was measured using the 15.0 eV plasmon peak of aluminum as an internal standard. Such measurements yielded a FWHM of 1.1 eV over the full image plane (fig. 1) with an optimum resolution of approximately 0.8 eV possible with corrections to the stability of the voltage supply and further small alignment adjustments.

This improved energy resolution permits the detection and imaging of signals in the low loss region previously inaccessible to us in the EM902.