Electron Energy Loss Fine Structure of Carbides and Nitrides

1985 ◽  
Vol 62 ◽  
Author(s):  
Mark M. Disko
Keyword(s):  
Electronic Structure ◽  
Energy Loss ◽  
Electron Energy ◽  
Spatial Resolution ◽  
High Spatial Resolution ◽  
High Strength ◽  
Analytical Technique ◽  
Wide Range ◽  
Wear Coatings ◽  
Electron Energy Loss

ABSTRACTTransition metal carbides and nitrides are important in a wide range of materials problems which include precipitates in high strength alloys and ceramic wear coatings. Electron energy loss spectroscopy (EELS) is a high spatial resolution (probe sizes < 100nm) analytical technique which is sensitive to variations in carbon or nitrogen stoichiometry. This sensitivity to light elements depends on the ability to relate the measured EELS spectrum to a material's electronic structure. The unique capabilities of EELS for the characterization of carbonitrides with high spatial resolution are discussed along with some of the experimental and analytical methods used to relate measured spectra to electronic structure. Data are presented for several members of the systems Ti-N-C and Cr-Fe-C.

Surface Plasmons: a Sensitive Diagnostic Tool for Characterizing Interfaces

1985 ◽  
Vol 43 ◽  
pp. 254-255
Author(s):  
M. R. Scheinfein
Keyword(s):  
Dielectric Constant ◽  
Energy Loss ◽  
Surface Plasmons ◽  
Electron Energy ◽  
Surface Plasmon ◽  
Spatial Resolution ◽  
High Spatial Resolution ◽  
Excitation Energies ◽  
Asymptotic Energy ◽  
Electron Energy Loss

There has been considerable interest in characterizing the electronic and chemical properties of interfaces and grain boundries at high spatial resolution. This abstract describes a technique which utilizes the energy dispersion of surface plasmons in the transmission electron energy loss spectrum to evaluate the local dielectric constant variation across interfaces. This technique is shown to yield extremely high spatial resolution.We have been conducting studies of interfaces in a VG HB-5 STEM located at NRRFSS which is equipped with a high resolution electron energy loss analyzer. In STEM, using small probes, a typical surface plasmon excited by 100 keV electrons (Al for example) reaches its asymptotic energy value at a scattering angle between.3 and.4 mr. Since we are convoluting the incident angular distribution with the surface plasmon intensities integrated over a collection aperture, the surface plasmon excitation energies are given by their asymptotic (in k-space) energy values. These asymptotic energy excitations are very sensitive functions of the thickness and dielectric constant [eg, 2-5] of the surrounding medium.

Microanalysis with high Spatial Resolution

1983 ◽  
Vol 31 ◽  
Author(s):  
P. E. Batson ◽  
C. R. M. Grovenor ◽  
D. A. Smith ◽  
C. Wong
Keyword(s):  
Electron Beam ◽  
Energy Loss ◽  
Inelastic Scattering ◽  
Electron Energy ◽  
Spatial Resolution ◽  
High Spatial Resolution ◽  
X Rays ◽  
Elemental Microanalysis ◽  
Bulk Plasmon ◽  
Electron Energy Loss

ABSTRACTElemental microanalysis, using x-rays and electron energy loss scattering, has been shown to be possible with electron beam probe sizes down to 0.5nm. This paper will discuss some practical problems, such as specimen drift, signal magnitude, and probe-specimen interaction when the probe is made very small. These problems have arisen in two studies: 1) an investigation of as segregation in poly-crystalline Si and 2) imaging of metal spheres with surface and bulk plasmon inelastic scattering.

Trends in Electron Energy Loss Spectroscopy

1977 ◽  
Vol 35 ◽  
pp. 228-229
Author(s):  
C. Colliex ◽  
P. Trebbia
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Electron Energy Loss Spectroscopy ◽  
Materials Science ◽  
Analytical Technique ◽  
Recent Developments ◽  
Quantitative Results ◽  
Electron Microscopes ◽  
Electron Energy Loss ◽  
Primary Electrons

The physical foundations for the use of electron energy loss spectroscopy towards analytical purposes, seem now rather well established and have been extensively discussed through recent publications. In this brief review we intend only to mention most recent developments in this field, which became available to our knowledge. We derive also some lines of discussion to define more clearly the limits of this analytical technique in materials science problems.The spectral information carried in both low ( 0<ΔE<100eV ) and high ( >100eV ) energy regions of the loss spectrum, is capable to provide quantitative results. Spectrometers have therefore been designed to work with all kinds of electron microscopes and to cover large energy ranges for the detection of inelastically scattered electrons (for instance the L-edge of molybdenum at 2500eV has been measured by van Zuylen with primary electrons of 80 kV). It is rather easy to fix a post-specimen magnetic optics on a STEM, but Crewe has recently underlined that great care should be devoted to optimize the collecting power and the energy resolution of the whole system.

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