Existence of Collective-excitation Energy Losses from an Electron Beam passing through Biological Materials

Nature ◽  
1967 ◽  
Vol 213 (5080) ◽  
pp. 1045-1047 ◽  
Author(s):  
C. D. JOHNSON ◽  
T. B. RYMER
Keyword(s):  
Electron Beam ◽  
Excitation Energy ◽  
Collective Excitation ◽  
Biological Materials ◽  
Energy Losses

Enhanced information from biological materials through technological improvements in cryo-electron microscopy

1992 ◽  
Vol 50 (1) ◽  
pp. 788-789
Author(s):  
Marc J.C. de Jong ◽  
Wim M. Busing ◽  
Max T. Otten
Keyword(s):  
Electron Microscopy ◽  
Electron Beam ◽  
Biological Materials ◽  
Electron Crystallography ◽  
Cryo Electron Microscopy ◽  
Transmission Electron ◽  
The Many ◽  
Technological Improvements ◽  
Beam Damage

Biological materials damage rapidly in the electron beam, limiting the amount of information that can be obtained in the transmission electron microscope. The discovery that observation at cryo temperatures strongly reduces beam damage (in addition to making it unnecessaiy to use chemical fixatives, dehydration agents and stains, which introduce artefacts) has given an important step forward to preserving the ‘live’ situation and makes it possible to study the relation between function, chemical composition and morphology.Among the many cryo-applications, the most challenging is perhaps the determination of the atomic structure. Henderson and co-workers were able to determine the structure of the purple membrane by electron crystallography, providing an understanding of the membrane's working as a proton pump. As far as understood at present, the main stumbling block in achieving high resolution appears to be a random movement of atoms or molecules in the specimen within a fraction of a second after exposure to the electron beam, which destroys the highest-resolution detail sought.

scholarly journals The instability of an electron beam with a finite radius in a boundless plasma

1996 ◽  
Vol 14 (4) ◽  
pp. 367-374 ◽  
Author(s):  
G. V. Lizunov ◽  
A. S. Volokitin ◽  
D. B. Skidanov
Keyword(s):  
Growth Rate ◽  
Electron Beam ◽  
Electron Beams ◽  
Wave Number ◽  
Energy Losses ◽  
Finite Radius ◽  
Wave Numbers ◽  
Surrounding Space ◽  
The Waves ◽  
Beam Dimension

Abstract. Within the framework of a linear theory, the instability of an electron beam with a finite radius in a cold magnetised boundless plasma is considered. It is shown that a finite beam dimension influences the generation of quasi-potential waves in two aspects: the perpendicular wave number is quantised so that the frequencies of the waves are subjected to strong selection; a new kind of instability appears due to wave energy losses by emission into surrounding space. Growth rate dependence of wave numbers and frequencies is investigated for typical parameters of experiments with electron beams in space.

scholarly journals Nature of Isoscalar Dipole Resonances in Heavy Nuclei

2018 ◽  
Vol 63 (12) ◽  
pp. 1043 ◽  
Author(s):  
V. I. Abrosimov ◽  
O. I. Davydovska
Keyword(s):  
Velocity Field ◽  
Excitation Energy ◽  
Collective Excitation ◽  
High Energy ◽  
Low Energy ◽  
Resonance Width ◽  
Heavy Nuclei ◽  
Translation Invariant ◽  
Dipole Resonance ◽  
Spherical Nuclei

The isoscalar dipole nuclear response reveals low- and high-energy resonances. The nature of isoscalar dipole resonances in heavy spherical nuclei is studied, by using a translation-invariant kinetic model of small oscillations of finite Fermi systems. Calculations of the velocity field at the centroid energy show a pure vortex character of the low-energy isoscalar dipole resonance in spherical nuclei and confirm the anisotropic compression character of the high-energy one. The evolution of the velocity field as a function of the excitation energy of the nucleus within the resonance width is studied. It is found that the low-energy isoscalar dipole resonance retains a vortex character, while with this collective excitation also involves a compression, as the energy increases. The high-energy resonance keeps the compression character with a change in the excitation energy within the resonance width, but the compression-expansion region of the velocity field related to this resonance shifts inside the nucleus.

scholarly journals Прохождение электронов с энергией 10 keV через массив диэлектрических каналов

2021 ◽  
Vol 47 (1) ◽  
pp. 35
Author(s):  
К.А. Вохмянина ◽  
Л.В. Мышеловка ◽  
Д.А. Колесников ◽  
В.С. Сотникова ◽  
А.А. Каплий ◽  
...  
Keyword(s):  
Electron Beam ◽  
Tilt Angle ◽  
Incident Beam ◽  
Beam Axis ◽  
Energy Losses ◽  
Channel Diameter ◽  
Inner Channel

The passage of 10 keV electron beam through a bundle of a hollow polysulfone fiber with an inner channel diameter of 160 ± 60 μm was studied. Dependence of a fraction of the electron beam transmitted through the channels on the tilt angle of the channels relative to the incident beam axis is measured. The fraction of electrons that experienced energy losses of less than 10% after passing through the channels was estimated.

Techniques for Transmission Electron Microscopy of Fiber-Matrix Interfaces in Aluminum Alloy-Boron Composites by Ion Erosio

1971 ◽  
Vol 29 ◽  
pp. 204-205
Author(s):  
G. G. Shaw
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Aluminum Alloy ◽  
Electron Beam ◽  
Pure Aluminum ◽  
Ion Milling ◽  
Transmission Electron ◽  
Fiber Matrix ◽  
Ion Erosion ◽  
Row Of Fibers

The morphology and composition of the fiber-matrix interface can best be studied by transmission electron microscopy and electron diffraction. For some composites satisfactory samples can be prepared by electropolishing. For others such as aluminum alloy-boron composites ion erosion is necessary.When one wishes to examine a specimen with the electron beam perpendicular to the fiber, preparation is as follows: A 1/8 in. disk is cut from the sample with a cylindrical tool by spark machining. Thin slices, 5 mils thick, containing one row of fibers, are then, spark-machined from the disk. After spark machining, the slice is carefully polished with diamond paste until the row of fibers is exposed on each side, as shown in Figure 1.In the case where examination is desired with the electron beam parallel to the fiber, preparation is as follows: Experimental composites are usually 50 mils or less in thickness so an auxiliary holder is necessary during ion milling and for easy transfer to the electron microscope. This holder is pure aluminum sheet, 3 mils thick.

Temperature Dependence of the Critical Electron Dose for Fatty Acid Monolayers

1982 ◽  
Vol 40 ◽  
pp. 78-79
Author(s):  
Kenneth H. Downing ◽  
Robert M. Glaeser
Keyword(s):  
Electron Beam ◽  
Fatty Acid ◽  
Inelastic Scattering ◽  
Temperature Dependence ◽  
Structural Damage ◽  
Direct Result ◽  
Second Step ◽  
Strong Temperature Dependence ◽  
Electron Dose ◽  
Covalent Bonds

The structural damage of molecules irradiated by electrons is generally considered to occur in two steps. The direct result of inelastic scattering events is the disruption of covalent bonds. Following changes in bond structure, movement of the constituent atoms produces permanent distortions of the molecules. Since at least the second step should show a strong temperature dependence, it was to be expected that cooling a specimen should extend its lifetime in the electron beam. This result has been found in a large number of experiments, but the degree to which cooling the specimen enhances its resistance to radiation damage has been found to vary widely with specimen types.

Lithography below 100 nm

1983 ◽  
Vol 41 ◽  
pp. 96-99
Author(s):  
L. D. Jackel
Keyword(s):  
Spatial Distribution ◽  
Electron Beam ◽  
Electron Scattering ◽  
Electron Beam Lithography ◽  
Substrate Material ◽  
Local Electron ◽  
Electron Dose ◽  
Positive Resist ◽  
Exposure Process

Most production electron beam lithography systems can pattern minimum features a few tenths of a micron across. Linewidth in these systems is usually limited by the quality of the exposing beam and by electron scattering in the resist and substrate. By using a smaller spot along with exposure techniques that minimize scattering and its effects, laboratory e-beam lithography systems can now make features hundredths of a micron wide on standard substrate material. This talk will outline sane of these high- resolution e-beam lithography techniques.We first consider parameters of the exposure process that limit resolution in organic resists. For concreteness suppose that we have a “positive” resist in which exposing electrons break bonds in the resist molecules thus increasing the exposed resist's solubility in a developer. Ihe attainable resolution is obviously limited by the overall width of the exposing beam, but the spatial distribution of the beam intensity, the beam “profile” , also contributes to the resolution. Depending on the local electron dose, more or less resist bonds are broken resulting in slower or faster dissolution in the developer.

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