Wood Anatomy of Brassicales: New Information, New Evolutionary Concepts

High resolution electron microscopy has been shown to give new information on defects(1) and phase transformations in solids (2,3). In a continuing program of lattice fringe imaging of alloys, we have applied this technique to the martensitic transformation in steels in order to characterize the atomic environments near twin, lath and αmartensite boundaries. This paper describes current progress in this program.Figures A and B show lattice image and conventional bright field image of the same area of a duplex Fe/2Si/0.1C steel described elsewhere(4). The microstructure consists of internally twinned martensite (M) embedded in a ferrite matrix (F). Use of the 2-beam tilted illumination technique incorporating a twin reflection produced {110} fringes across the microtwins.

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Stereo Electron Microscopy Applied to High Resolution Freeze-Etch Replicas

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100068527 ◽

1970 ◽

Vol 28 ◽

pp. 306-307

Author(s):

L. Andrew Staehelin

Keyword(s):

Electron Microscopy ◽

Plastic Deformation ◽

High Resolution ◽

Smooth Surfaces ◽

Small Particles ◽

Membrane Surfaces ◽

Wide Acceptance ◽

New Information ◽

Number Of Particles ◽

Small Holes

Freeze-etched membranes usually appear as relatively smooth surfaces covered with numerous small particles and a few small holes (Fig. 1). In 1966 Branton (1“) suggested that these surfaces represent split inner mem¬brane faces and not true external membrane surfaces. His theory has now gained wide acceptance partly due to new information obtained from double replicas of freeze-cleaved specimens (2,3) and from freeze-etch experi¬ments with surface labeled membranes (4). While theses studies have fur¬ther substantiated the basic idea of membrane splitting and have shown clearly which membrane faces are complementary to each other, they have left the question open, why the replicated membrane faces usually exhibit con¬siderably fewer holes than particles. According to Branton's theory the number of holes should on the average equal the number of particles. The absence of these holes can be explained in either of two ways: a) it is possible that no holes are formed during the cleaving process e.g. due to plastic deformation (5); b) holes may arise during the cleaving process but remain undetected because of inadequate replication and microscope techniques.

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Trial production of γ-type energy filtering TEM

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100139391 ◽

1995 ◽

Vol 53 ◽

pp. 604-605

Author(s):

Y. Taniguchi ◽

E. Nakazawa ◽

S. Taya

Keyword(s):

Magnetic Energy ◽

Electron Optics ◽

Electron Microscopic ◽

Mass Spectrometers ◽

Ion Optics ◽

Energy Filtering ◽

New Information ◽

New Type ◽

Fringing Fields

Imaging energy filters can add new information to electron microscopic images with respect to energy-axis, so-called electron spectroscopic imaging (ESI). Recently, many good results have been reported using this imaging technique. ESI also allows high-contrast observation of unstained biological samples, becoming a trend of the field of morphology. We manufactured a new type of energy filter as a trial production. This energy filter consists of two magnets, and we call γ-filter since the trajectory of electrons shows ‘γ’-shape inside the filter. We evaluated the new energyγ-filter TEM with the γ-filter.Figure 1 shows schematic view of the electron optics of the γ-type energy filter. For the determination of the electron-optics of the γ-type energy filter, we used the TRIO (Third Order Ion Optics) program which has been developed for the design of high resolution mass spectrometers. The TRIO takes the extended fringing fields (EFF) into consideration. EFF makes it difficult to design magnetic energy filters with magnetic sector fields.

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Principles of Low-Vacuum SEM

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100131152 ◽

1992 ◽

Vol 50 (2) ◽

pp. 1304-1305

Author(s):

Klaus-Ruediger Peters

Keyword(s):

New Technologies ◽

High Vacuum ◽

Optical Microscope ◽

Specimen Surface ◽

Electrical Field ◽

Gaseous Environment ◽

New Information ◽

Gas Molecules ◽

New Interactions ◽

Gas Pressures

Only recently it became possible to expand scanning electron microscopy to low vacuum and atmospheric pressure through the introduction of several new technologies. In principle, only the specimen is provided with a controlled gaseous environment while the optical microscope column is kept at high vacuum. In the specimen chamber, the gas can generate new interactions with i) the probe electrons, ii) the specimen surface, and iii) the specimen-specific signal electrons. The results of these interactions yield new information about specimen surfaces not accessible to conventional high vacuum SEM. Several microscope types are available differing from each other by the maximum available gas pressure and the types of signals which can be used for investigation of specimen properties.Electrical non-conductors can be easily imaged despite charge accumulations at and beneath their surface. At high gas pressures between 10-2 and 2 torr, gas molecules are ionized in the electrical field between the specimen surface and the surrounding microscope parts through signal electrons and, to a certain extent, probe electrons. The gas provides a stable ion flux for a surface charge equalization if sufficient gas ions are provided.

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Modern TEM systems architecture

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100144486 ◽

1986 ◽

Vol 44 ◽

pp. 602-605

Author(s):

U. Gross ◽

P. Hagemann

Keyword(s):

Electron Microscope ◽

Information Gathering ◽

Systems Architecture ◽

Control Functions ◽

Transmission Electron ◽

New Information ◽

Comprehensive Information ◽

Scanning Transmission ◽

Diffraction Patterns ◽

Analytical Equipment

By addition of analytical equipment, scanning transmission accessories and data processing equipment the basic transmission electron microscope (TEM) has evolved into a comprehensive information gathering system. This extension has led to increased complexity of the instrument as compared with the straightforward imaging microscope, since in general new information capacity has required the addition of new control hardware. The increased operational complexity is reflected in a proliferation of knobs and buttons.In the conventional electron microscope design the operating panel of the instrument has distinct control elements to alter optical conditions of the microscope column in different modes. As a consequence a multiplicity of control functions has been inevitable. Examples of this are the three pairs of focus and magnification controls needed for TEM imaging, diffraction patterns, and STEM images.

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X-ray microprobe for materials science

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100168013 ◽

1994 ◽

Vol 52 ◽

pp. 56-57

Author(s):

G.E. Ice

Keyword(s):

Crystallographic Orientation ◽

Local Structure ◽

Materials Science ◽

Chemical Information ◽

X Ray Diffraction ◽

Ray Optics ◽

X Ray ◽

Novel Materials ◽

New Information ◽

Elemental Sensitivity

The increasing availability of synchrotron x-ray sources has stimulated the development of advanced hard x-ray (E≥5 keV) microprobes. With new x-ray optics these microprobes can achieve micron and submicron spatial resolutions. The inherent elemental and crystallographic sensitivity of an x-ray microprobe and its inherently nondestructive and penetrating nature will have important applications to materials science. For example, x-ray fluorescent microanalysis of materials can reveal elemental distributions with greater sensitivity than alternative nondestructive probes. In materials, segregation and nonuniform distributions are the rule rather than the exception. Common interfaces to whichsegregation occurs are surfaces, grain and precipitate boundaries, dislocations, and surfaces formed by defects such as vacancy and interstitial configurations. In addition to chemical information, an x-ray diffraction microprobe can reveal the local structure of a material by detecting its phase, crystallographic orientation and strain.Demonstration experiments have already exploited the penetrating nature of an x-ray microprobe and its inherent elemental sensitivity to provide new information about elemental distributions in novel materials.

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