scholarly journals 275  W/m2 collection efficiency solar laser using a diffuse scattering cooling liquid: erratum

2020 ◽  
Vol 59 (3) ◽  
pp. 800
Author(s):  
C. J. C. Smyth ◽  
S. Mirkhanov ◽  
A. H. Quarterman ◽  
K. G. Wilcox
Keyword(s):  
Diffuse Scattering ◽  
Collection Efficiency ◽  
Cooling Liquid

scholarly journals 275  W/m2 collection efficiency solar laser using a diffuse scattering cooling liquid

2018 ◽  
Vol 57 (15) ◽  
pp. 4008 ◽  
Author(s):  
C. J. C. Smyth ◽  
S. Mirkhanov ◽  
A. H. Quarterman ◽  
K. G. Wilcox
Keyword(s):  
Diffuse Scattering ◽  
Collection Efficiency ◽  
Cooling Liquid

To What Extent are Inelastically Scattered Electrons Useful in the Stem?

1973 ◽  
Vol 31 ◽  
pp. 286-287 ◽  
Author(s):  
H. Rose
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
Electron Correlation ◽  
Quantum Noise ◽  
Collection Efficiency ◽  
Scanning Transmission Electron Microscope ◽  
Electron Cloud ◽  
Scanning Time ◽  
Transmission Electron ◽  
Scanning Transmission

The scanning transmission electron microscope offers the possibility of utilizing inelastically scattered electrons. Use of these electrons in addition to the elastically scattered electrons should reduce the scanning time (dose) Which is necessary to keep the quantum noise below a certain level. Hence it should lower the radiation damage. For high resolution, Where the collection efficiency of elastically scattered electrons is small, the use of Inelastically scattered electrons should become more and more favorable because they can all be detected by means of a spectrometer. Unfortunately, the Inelastic scattering Is a non-localized interaction due to the electron-electron correlation, occurring predominantly at the circumference of the atomic electron cloud.

Calculation of structure images of crystalline defects

1978 ◽  
Vol 36 (1) ◽  
pp. 282-283
Author(s):  
M.A. O'Keefe ◽  
Sumio Iijima
Keyword(s):  
Diffuse Scattering ◽  
Computing Time ◽  
Continuous Distribution ◽  
Sampling Interval ◽  
Reciprocal Space ◽  
Objective Lens ◽  
Lattice Images ◽  
Slice Method ◽  
Space Cell ◽  
Beam Lattice

We have extended the multi-slice method of computating many-beam lattice images of perfect crystals to calculations for imperfect crystals using the artificial superlattice approach. Electron waves scattered from faulted regions of crystals are distributed continuously in reciprocal space, and all these waves interact dynamically with each other to give diffuse scattering patterns.In the computation, this continuous distribution can be sampled only at a finite number of regularly spaced points in reciprocal space, and thus finer sampling gives an improved approximation. The larger cell also allows us to defocus the objective lens further before adjacent defect images overlap, producing spurious computational Fourier images. However, smaller cells allow us to sample the direct space cell more finely; since the two-dimensional arrays in our program are limited to 128X128 and the sampling interval shoud be less than 1/2Å (and preferably only 1/4Å), superlattice sizes are limited to 40 to 60Å. Apart from finding a compromis superlattice cell size, computing time must be conserved.

High energy resolution spectrometer for the dedicated STEM

1984 ◽  
Vol 42 ◽  
pp. 558-559 ◽  
Author(s):  
P.E. Batson
Keyword(s):  
Collection Efficiency ◽  
Core Loss ◽  
Beam Current ◽  
High Energy ◽  
High Energy Resolution ◽  
Acquisition Time ◽  
Good Definition ◽  
Loss Analysis ◽  
Definition Of ◽  
Acceleration Voltage

Use of the STEM to obtain precise electronic information has been hampered by the lack of energy loss analysis capable of a resolution and accuracy comparable to the 0.3eV energy width of the Field Emission Source. Recent work by Park, et. al. and earlier by Crewe, et. al. have promised magnetic sector devices that are capable of about 0.75eV resolution at collection angles (about 15mR) which are great enough to allow efficient use of the STEM probe current. These devices are also capable of 0.3eV resolution at smaller collection angles (4-5mR). The problem that arises, however, lies in the fact that, even with the collection efficiency approaching 1.0, several minutes of collection time are necessary for a good definition of a typical core loss or electronic transition. This is a result of the relatively small total beam current (1-10nA) that is available in the dedicated STEM. During this acquisition time, the STEM acceleration voltage may fluctuate by as much as 0.5-1.0V.

High spatial resolution x-ray microanalysis of interfaces

1995 ◽  
Vol 53 ◽  
pp. 284-285
Author(s):  
J. R. Michael
Keyword(s):  
Spatial Resolution ◽  
Electron Probe ◽  
Solid Angle ◽  
Collection Efficiency ◽  
Spatial Scales ◽  
Energy Dispersive Spectrometer ◽  
X Rays ◽  
X Ray ◽  
Probe Size ◽  
Brightness Field

X-ray microanalysis in the analytical electron microscope (AEM) refers to a technique by which chemical composition can be determined on spatial scales of less than 10 nm. There are many factors that influence the quality of x-ray microanalysis. The minimum probe size with sufficient current for microanalysis that can be generated determines the ultimate spatial resolution of each individual microanalysis. However, it is also necessary to collect efficiently the x-rays generated. Modern high brightness field emission gun equipped AEMs can now generate probes that are less than 1 nm in diameter with high probe currents. Improving the x-ray collection solid angle of the solid state energy dispersive spectrometer (EDS) results in more efficient collection of x-ray generated by the interaction of the electron probe with the specimen, thus reducing the minimum detectability limit. The combination of decreased interaction volume due to smaller electron probe size and the increased collection efficiency due to larger solid angle of x-ray collection should enhance our ability to study interfacial segregation.

Low-workfunction field-emission source for high-resolution EELS

1987 ◽  
Vol 45 ◽  
pp. 132-133
Author(s):  
P. E. Batson
Keyword(s):  
High Resolution ◽  
Energy Loss ◽  
Electron Probe ◽  
Collection Efficiency ◽  
Electron Sources ◽  
Wien Filter ◽  
Half Angle ◽  
Thermal Emitter ◽  
Electron Energy Loss ◽  
Intrinsic Energy

In recent years,instrumentation for electron energy loss spectroscopy (EELS) has been steadily improved to increase energy resolution and collection efficiency. At present 0.40eV at 10mR collection half angle is available with commercial magnetic sectors (e.g. Gatan, Inc. and VG Microscopes, Ltd.), and 70meV at 10mR has been demonstrated by use of a Wien filter within a large deceleration field. When these high resolution spectrometers are coupled to the modern small electron probe instrument, we obtain a tool which promises to reveal local changes in bandstructure and bonding near defects and interfaces in heterogeneous materials.Unfortunately, typical electron sources have intrinsic energy widths which limit attainable spectroscopic resolution in the absence of some monochromation system. For instance, the W thermal emitter has a half width of about 1eV.

Recent applications of TEM to the study of interfaces

1990 ◽  
Vol 48 (4) ◽  
pp. 308-309
Author(s):  
C. Barry Carter
Keyword(s):  
High Resolution ◽  
Sample Preparation ◽  
Grain Boundaries ◽  
Diffuse Scattering ◽  
Imaging Techniques ◽  
Amorphous Material ◽  
Contrast Imaging ◽  
Current State ◽  
Actual Nature ◽  
High Resolution Images

This paper will review the current state of understanding of interface structure and highlight some of the future needs and problems which must be overcome. The study of this subject can be separated into three different topics: 1) the fundamental electron microscopy aspects, 2) material-specific features of the study and 3) the characteristics of the particular interfaces. The two topics which are relevant to most studies are the choice of imaging techniques and sample preparation. The techniques used to study interfaces in the TEM include high-resolution imaging, conventional diffraction-contrast imaging, and phase-contrast imaging (Fresnel fringe images, diffuse scattering). The material studied affects not only the characteristics of the interfaces (through changes in bonding, etc.) but also the method used for sample preparation which may in turn have a significant affect on the resulting image. Finally, the actual nature and geometry of the interface must be considered. For example, it has become increasingly clear that the plane of the interface is particularly important whenever at least one of the adjoining grains is crystalline.A particularly productive approach to the study of interfaces is to combine different imaging techniques as illustrated in the study of grain boundaries in alumina. In this case, the conventional imaging approach showed that most grain boundaries in ion-thinned samples are grooved at the grain boundary although the extent of this grooving clearly depends on the crystallography of the surface. The use of diffuse scattering (from amorphous regions) gives invaluable information here since it can be used to confirm directly that surface grooving does occur and that the grooves can fill with amorphous material during sample preparation (see Fig. 1). Extensive use of image simulation has shown that, although information concerning the interface can be obtained from Fresnel-fringe images, the introduction of artifacts through sample preparation cannot be lightly ignored. The Fresnel-fringe simulation has been carried out using a commercial multislice program (TEMPAS) which was intended for simulation of high-resolution images.

Electron beam induced current study of thin silicon layers on insulator substrate

1990 ◽  
Vol 48 (4) ◽  
pp. 618-619
Author(s):  
A. Buczkowski ◽  
Z. J. Radzimski ◽  
J. C. Russ ◽  
G. A. Rozgonyi
Keyword(s):  
Electron Beam ◽  
Energy Loss ◽  
Beam Energy ◽  
Collection Efficiency ◽  
Silicon Layer ◽  
Depletion Layer ◽  
Incident Electron Energy ◽  
Induced Current ◽  
Electron Hole ◽  
Electron Beam Induced Current

If a thickness of a semiconductor is smaller than the penetration depth of the electron beam, e.g. in silicon on insulator (SOI) structures, only a small portion of incident electrons energy , which is lost in a superficial silicon layer separated by the oxide from the substrate, contributes to the electron beam induced current (EBIC). Because the energy loss distribution of primary beam is not uniform and varies with beam energy, it is not straightforward to predict the optimum conditions for using this technique. Moreover, the energy losses in an ohmic or Schottky contact complicate this prediction. None of the existing theories, which are based on an assumption of a point-like region of electron beam generation, can be used satisfactorily on SOI structures. We have used a Monte Carlo technique which provide a simulation of the electron beam interactions with thin multilayer structures. The EBIC current was calculated using a simple one dimensional geometry, i.e. depletion layer separating electron- hole pairs spreads out to infinity in x- and y-direction. A point-type generation function with location being an actual location of an incident electron energy loss event has been assumed. A collection efficiency of electron-hole pairs was assumed to be 100% for carriers generated within the depletion layer, and inversely proportional to the exponential function of depth with the effective diffusion length as a parameter outside this layer. A series of simulations were performed for various thicknesses of superficial silicon layer. The geometries used for simulations were chosen to match the "real" samples used in the experimental part of this work. The theoretical data presented in Fig. 1 show how significandy the gain decreases with a decrease in superficial layer thickness in comparison with bulk material. Moreover, there is an optimum beam energy at which the gain reaches its maximum value for particular silicon thickness.

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