Numerical and theoretical modeling of the sheath upstream of ion optics: sheath structure transition and its effect on the beam divergence

There is increasing interest in X-ray microanalysis of thin specimens and the present paper attempts to define some of the factors which govern the spatial resolution of this type of microanalysis. One of these factors is the spreading of the electron probe as it is transmitted through the specimen. There will always be some beam-spreading with small electron probes, because of the inevitable beam divergence associated with small, high current probes; a lower limit to the spatial resolution is thus 2αst where 2αs is the beam divergence and t the specimen thickness.In addition there will of course be beam spreading caused by elastic and inelastic interaction between the electron beam and the specimen. The angle through which electrons are scattered by the various scattering processes can vary from zero to 180° and it is clearly a very complex calculation to determine the effective size of the beam as it propagates through the specimen.

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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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Electron Channelling Contrast Imaging of Dislocations

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100181762 ◽

1990 ◽

Vol 48 (1) ◽

pp. 600-601

Author(s):

J.T. Czernuszka ◽

N.J. Long ◽

P.B. Hirsch

Keyword(s):

Field Emission ◽

Secondary Electron ◽

Surface Defects ◽

Spot Size ◽

Beam Divergence ◽

Contrast Imaging ◽

Scattered Electron ◽

Near Surface ◽

Filter System ◽

Electron Channelling

In the 1970s there was considerable interest in the development of the electron channelling contrast imaging (ECCI) technique for imaging near surface defects in bulk (electron opaque) specimens. The predictions of the theories were realised experimentally by Morin et al., who used a field emission gun (FEG) operating at 40-50kV and an energy filter such that only electrons which had lost no more than a few 100V were detected. This paper presents the results of a set of preliminary experiments which show that an energy filter system is unneccessary to image and characterise the Burgers vectors of dislocations in bulk specimens. The examples in the paper indicatethe general versatility of the technique.A VG HB501 STEM with a FEG was operated at 100kV. A single tilt cartridge was used in the reflection position of the microscope. A retractable back-scattered electron detector was fitted into the secondary electron port and positioned to within a few millimetres of the specimen. The image was acquired using a Synoptics Synergy framestore and digital scan generator and subsequently processed using Semper 6. The beam divergence with the specimen in this position was 2.5 mrads with a spot size of approximately 4nm. Electron channelling patterns were used to orientate the sample.

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The role of ligands in electron transport in nanocrystal solids

Nanoscale ◽

10.1039/d0nr06892f ◽

2020 ◽

Vol 12 (45) ◽

pp. 23028-23035

Author(s):

Artem R. Khabibullin ◽

Alexander L. Efros ◽

Steven C. Erwin

Keyword(s):

Electron Transport ◽

Theoretical Modeling

Theoretical modeling of wavefunction overlap in nanocrystal solids elucidates the important role played by ligands in electron transport.

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Hysteresis in spectral state transitions – a challenge for theoretical modeling

Astronomy and Astrophysics ◽

10.1051/0004-6361:20041631 ◽

2005 ◽

Vol 432 (1) ◽

pp. 181-187 ◽

Cited By ~ 58

Author(s):

E. Meyer-Hofmeister ◽

B. F. Liu ◽

F. Meyer

Keyword(s):

Theoretical Modeling ◽

State Transitions ◽

Spectral State

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Control of proton beam divergence in intense-laser foil-plasma interaction

Journal de Physique IV (Proceedings) ◽

10.1051/jp4:2006133113 ◽

2006 ◽

Vol 133 ◽

pp. 549-551 ◽

Cited By ~ 1

Author(s):

S. Kawata ◽

R. Sonobe ◽

S. Miyazaki ◽

K. Sakai ◽

T. Kikuchi

Keyword(s):

Proton Beam ◽

Beam Divergence ◽

Intense Laser ◽

Plasma Interaction

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Ion optics in a 14 UD Pelletron terminal

Revue de Physique Appliquée ◽

10.1051/rphysap:0197700120100156300 ◽

1977 ◽

Vol 12 (10) ◽

pp. 1563-1566

Author(s):

Z. Segalov ◽

E. Skurnik

Keyword(s):

Ion Optics

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Epistemological Status of Models and Thought Experiments in Economics

Voprosy Ekonomiki ◽

10.32609/0042-8736-2015-2-123-140 ◽

2015 ◽

pp. 123-140 ◽

Cited By ~ 1

Author(s):

O. Koshovets ◽

T. Varkhotov

Keyword(s):

Natural Science ◽

Thought Experiment ◽

Thought Experiments ◽

Theoretical Modeling ◽

Epistemological Status ◽

Epistemological Analysis ◽

Field Of Inquiry

The paper considers the analogy of theoretical modeling and thought experiment in economics. The authors provide historical and epistemological analysis of thought experiments and their relations to the material experiments in natural science. They conclude that thought experiments as instruments are used both in physics and in economics, but in radically different ways. In the natural science, a thought experiment is tightly connected to the material experimentation, while in economics it is used in isolation. Material experiments serve as a means to demonstrate the reality, while thought experiments cannot be a full-fledged instrument of studying the reality. Rather, they constitute the instrument of structuring the field of inquiry.

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Theoretical modeling of the regular olivine intergrowths in the mimetic paramorphosis after ringwoodite and wadsleyite

Moscow University Bulletin. Series 4. Geology ◽

10.33623/0579-9406-2018-4-3-12 ◽

2018 ◽

pp. 3-12

Author(s):

B. B. Shkursky

Keyword(s):

Transition Zone ◽

Theoretical Modeling ◽

Mantle Transition Zone ◽

Misorientation Angles

Theoretical modeling of regular olivine grains misorientations in mimetic paramorphoses after ringwoodite and wadsleyite, the formation of which during the ascension of matter from the Mantle Transition Zone is expected, has been carried out. The coordinates of the misorientation axes and the misorientation angles, characterizing 10 operations of alignment in the pair intergrowths of olivine grains, eight of which are twins, are calculated. Possible conditions for the formation of mimetic paramorphoses predicted here, and the chances of their persistence are discussed. The calculated orientations are compared with the known twinning laws of olivine.

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