scholarly journals Dissociation path competition of radiolysis ionization-induced molecule damage under electron beam illumination

2019 ◽  
Vol 10 (46) ◽  
pp. 10706-10715 ◽  
Author(s):  
Zenghua Cai ◽  
Shiyou Chen ◽  
Lin-Wang Wang
Keyword(s):  
Electron Beam ◽  
Ab Initio ◽  
Mass Spectra ◽  
Dissociation Path

Molecule damage under TEM electron beam illumination is studied using a systematical ab initio method. Three main dissociation paths are revealed which explains the experimentally observed mass spectra of the dissociation fragments of the C2H6O2+.

Behavior of hydrogen atoms in the fragmentation of CH3CD3

1977 ◽  
Vol 55 (17) ◽  
pp. 3124-3131 ◽  
Author(s):  
Isao H. Suzuki ◽  
Kogoro Maeda
Keyword(s):  
Electron Beam ◽  
Electron Energy ◽  
Mass Spectra ◽  
Ionization Efficiency ◽  
Hydrogen Atoms ◽  
Monoenergetic Electron ◽  
Monoenergetic Electron Beam

The behavior of hydrogen atoms in the fragmentation of CH3CD3 has been studied by use of a monoenergetic electron beam. Ionization efficiency curves for ions (m/e 3, 4, 15 to 18, 26 to 33) from CH3CD3 have been measured over ranges of 12 to 30 eV near their appearance thresholds. Mass spectra over various ranges of m/e have been measured at several electron energies. It has been found that at least two processes participate in the formation of C2X4+ and CH3+(X = H or D) and the rates of these processes depend on the energy of electron beam. The formations of C2X2+ and X2+ are independent of the electron energy.

Combined electron beam imaging and ab initio modeling of T1 precipitates in Al–Li–Cu alloys

2011 ◽  
Vol 98 (20) ◽  
pp. 201909 ◽  
Author(s):  
C. Dwyer ◽  
M. Weyland ◽  
L. Y. Chang ◽  
B. C. Muddle
Keyword(s):  
Electron Beam ◽  
Ab Initio ◽  
Ab Initio Modeling ◽  
Cu Alloys

Electron diffraction of copper perfluorophthalocyanine on the HVEM

1995 ◽  
Vol 53 ◽  
pp. 158-159
Author(s):  
W. F. Tivol ◽  
J. R. Fryer
Keyword(s):  
Electron Beam ◽  
Electron Diffraction ◽  
Ab Initio ◽  
Vapor Phase ◽  
High Energy ◽  
Illumination Level ◽  
Objective Lens ◽  
Crystal Face ◽  
Correct Orientation ◽  
Diffraction Patterns

The use of high-energy (1200 kV) electrons has been shown to be advantageous in the ab initio structure analysis from electron diffraction of organic compounds. Previous studies showed that ab initio analysis of copper perchlorophthalocyanine could be accomplished at accelerating voltages at or above 1000 kV, but not at 400 kV for crystals which are about 10 nm thick. Copper perbromophthalocyanine could also be analyzed ab initio at 1200 kV, but the presence of severe dynamical scattering precluded such analysis at lower voltages.Copper perfluorophthalocyanine (Cu FPC) was grown epitaxially from the vapor phase onto a clean KC1 crystal face. Electron diffraction patterns were obtained from crystals tilted at 20° and oriented so that the electron beam was parallel to the c-axis.Electron doses were kept to a minimum by the use of a 100 μm condenser aperture and a highly excited first condenser lens. A video system allows scanning the specimen to find a crystal suitable for the correct orientation of the grid by rotating it within its own plane and focusing the objective lens, all at an illumination level below that necessary to distinguish anything by eye on the HVEM's phosphor screen.

Dislocation Kink Motion - Ab-Initio Calculations and Atomic Resolution Movies

1995 ◽  
Vol 408 ◽  
Author(s):  
J. C. H. Spence ◽  
H. R. Kolar ◽  
Y. Huang ◽  
H. Alexandera
Keyword(s):  
Electron Beam ◽  
Ab Initio ◽  
Energy Barrier ◽  
Partial Dislocation ◽  
Atomic Resolution ◽  
Migration Energy ◽  
Valence Electrons ◽  
Tensile Forces ◽  
And Migration ◽  
Band Structure Energy

AbstractThe results of recent ab-initio, relaxed, computations for the energy barrier to the motion of a kink on a 30° partial dislocation in silicon are summarised. The electronic structure and charge density are given. We suggest that the shearing motions involved with ductility and kink motion are controlled by the band structure energy involving valence electrons, whereas the tensile forces involved in fracture depend on both ion-ion and valence forces. Experimental atomic resolution TEM images of dissociated dislocation lines in silicon are discussed. These are formed using “forbidden reflections” with the dislocation lines lying on (111), normal to the electron beam. For images of samples at 600 C recorded at video rates, differences between successive frames reveal the motion of individual kinks, from which the kink velocity and migration energy can be 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.

Domain Formation in Synthetic Quartz

1971 ◽  
Vol 29 ◽  
pp. 156-157
Author(s):  
Joseph J. Comer
Keyword(s):  
Electron Beam ◽  
Room Temperature ◽  
Domain Formation ◽  
Synthetic Quartz ◽  
Transmission Electron ◽  
Black Spots ◽  
Diffraction Mode ◽  
Domain Boundaries ◽  
Kikuchi Lines ◽  
Straight Lines

Domains visible by transmission electron microscopy, believed to be Dauphiné inversion twins, were found in some specimens of synthetic quartz heated to 680°C and cooled to room temperature. With the electron beam close to parallel to the [0001] direction the domain boundaries appeared as straight lines normal to <100> and <410> or <510> directions. In the selected area diffraction mode, a shift of the Kikuchi lines was observed when the electron beam was made to traverse the specimen across a boundary. This shift indicates a change in orientation which accounts for the visibility of the domain by diffraction contrast when the specimen is tilted. Upon exposure to a 100 KV electron beam with a flux of 5x 1018 electrons/cm2sec the boundaries are rapidly decorated by radiation damage centers appearing as black spots. Similar crystallographio boundaries were sometimes found in unannealed (0001) quartz damaged by electrons.

Materials for Electron Beam Information Storage

1969 ◽  
Vol 27 ◽  
pp. 152-153 ◽  
Author(s):  
D. E. Speliotis
Keyword(s):  
Magnetic Field ◽  
Electron Beam ◽  
Recent Literature ◽  
Electron Beams ◽  
Information Storage ◽  
The Subject ◽  
The Magnetic Field

The interaction of electron beams with a large variety of materials for information storage has been the subject of numerous proposals and studies in the recent literature. The materials range from photographic to thermoplastic and magnetic, and the interactions with the electron beam for writing and reading the information utilize the energy, or the current, or even the magnetic field associated with the electron beam.

Application of Improved Voltage Compensation in the SEM to Imaging of Organic Materials

1973 ◽  
Vol 31 ◽  
pp. 444-445
Author(s):  
P.J. Killingworth ◽  
M. Warren
Keyword(s):  
Electron Beam ◽  
Organic Materials ◽  
Operating Parameters ◽  
Low Density ◽  
Beam Diameter ◽  
Incident Electron Beam ◽  
Specimen Material ◽  
Voltage Compensation ◽  
Selection Of ◽  
Scanning Electron

Ultimate resolution in the scanning electron microscope is determined not only by the diameter of the incident electron beam, but by interaction of that beam with the specimen material. Generally, while minimum beam diameter diminishes with increasing voltage, due to the reduced effect of aberration component and magnetic interference, the excited volume within the sample increases with electron energy. Thus, for any given material and imaging signal, there is an optimum volt age to achieve best resolution.In the case of organic materials, which are in general of low density and electric ally non-conducting; and may in addition be susceptible to radiation and heat damage, the selection of correct operating parameters is extremely critical and is achiev ed by interative adjustment.

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