Calculation of intravalley and intervalley transition probabilities in the course of electron scattering by a gallium arsenide surface

1990 ◽  
Vol 33 (3) ◽  
pp. 237-240
Author(s):  
V. A. Goryunov ◽  
V. N. Chernyshov
Keyword(s):  
Gallium Arsenide ◽  
Electron Scattering ◽  
Transition Probabilities

Inelastic Electron Scattering from 20,22Ne

1973 ◽  
Vol 51 (20) ◽  
pp. 2125-2137 ◽  
Author(s):  
R. P. Singhal ◽  
H. S. Caplan ◽  
J. R. Moreira ◽  
T. E. Drake
Keyword(s):  
Momentum Transfer ◽  
Excited States ◽  
Electron Scattering ◽  
Ground State ◽  
State Transition ◽  
Transition Probabilities ◽  
Limited Range ◽  
Particle Model ◽  
Inelastic Electron ◽  
Momentum Transfer Range

The scattering of electrons from the low lying excited states of 20Ne and 22Ne has been studied in the momentum transfer range from 0.41 fm−1 to 1.04 fm−1. Over a limited range of momentum transfer the study of 20Ne has been extended to excited states up to 8 MeV. A phase shift code has been used to extract the ground state transition probabilities of the states observed. The model dependence of the results is investigated. The experimental results have been compared with the predictions of the Nilsson and the alpha-particle model.

scholarly journals Notizen: Evidence of Ml and E2 Strength in the Giant Resonance Region of Ce

1972 ◽  
Vol 27 (11) ◽  
pp. 1683-1684 ◽  
Author(s):  
R. Pitthan ◽  
Th. Walcher
Keyword(s):  
Electron Scattering ◽  
Transition Probabilities ◽  
Giant Resonance ◽  
Resonance Region ◽  
Inelastic Electron ◽  
Inelastic Electron Scattering ◽  
Reduced Transition Probabilities

Abstract Inelastic electron scattering from Ce (50 and 65 MeV, 93°, 129° and 165°) had shown evidence for an Ml and an E2 resonance at 8.7 and 12.0 MeV, respectively. These assignments have been confirmed by DWBA calculations. Reduced transition probabilities are derived for the resonances mentioned, and for the giant E1 resonance.

scholarly journals Core-polarization effect in longitudinal electron scattering form factors of 65Cu nucleus

2019 ◽  
Vol 14 (31) ◽  
pp. 13-27
Author(s):  
Adie D. Salman
Keyword(s):  
Experimental Data ◽  
Shell Model ◽  
Electron Scattering ◽  
Transition Probabilities ◽  
Effective Interaction ◽  
Form Factors ◽  
Model Space ◽  
Inelastic Electron ◽  
Core Polarization ◽  
Reduced Transition Probabilities

Inelastic longitudinal electron scattering form factors to 2+ and 4+ states in 65Cu nucleus has been calculated in the (2p3/2 1f 5/2 2p1/2) shell model space with the F5PVH effective interaction. The harmonic oscillator potential has been applied to calculate the wave functions of radial single-particle matrix elements. Two shell model codes, CP and NUSHELL are used to obtain results. The form factor of inelastic electron scattering to 1/21−, 1/22−, 3/22−, 3/23−, 5/21−, 5/22− and 7/2- states and finding the transition probabilities B (C2) (in units of e2 fm4) for these transitions and B (C4) (in units of e2 fm8) for the transition 7/2-, and comparing them with experimental data. Both the form factors and reduced transition probabilities with core-polarization effects gave a reasonable description of the experimental data.

scholarly journals Electromagnetic multipole of positive and negative parity states in 24Mg by elastic and inelastic electron scattering

2019 ◽  
Vol 17 (42) ◽  
pp. 27-41
Author(s):  
NOORI S. Manie
Keyword(s):  
Experimental Data ◽  
Shell Model ◽  
Electron Scattering ◽  
Single Particle ◽  
Transition Probabilities ◽  
Form Factors ◽  
Negative Parity ◽  
Inelastic Electron ◽  
Hartree Fock ◽  
Inelastic Electron Scattering

In the present work, the nuclear shell model with Hartree–Fock (HF) calculations have been used to investigate the nuclear structure of 24Mg nucleus. Particularly, elastic and inelastic electron scattering form factors and transition probabilities have been calculated for low-lying positive and negative states. The sd and sdpf shell model spaces have been used to calculate the one-body density matrix elements (OBDM) for positive and negative parity states respectively. Skyrme-Hartree-Fock (SHF) with different parameterizations has been tested with shell model calculation as a single particle potential for reproducing the experimental data along with a harmonic oscillator (HO) and Woods-Saxon (WS) single-particle potentials. The effect of the nuclear effective charge has been implemented via using different folding models; valance, Tassie and Bohr-Mottelson. The evaluated results have been discussed and compared with available experimental data.

Inelastic Electron Scattering from 18O

1971 ◽  
Vol 49 (22) ◽  
pp. 2743-2753 ◽  
Author(s):  
J. L. Groh ◽  
R. P. Singhal ◽  
H. S. Caplan ◽  
B. S. Dolbilkin
Keyword(s):  
Electron Scattering ◽  
Cross Sections ◽  
Ground State ◽  
Transition Probabilities ◽  
Form Factors ◽  
Wave Functions ◽  
Inelastic Electron ◽  
Inelastic Electron Scattering ◽  
Momentum Transfer Range ◽  
Scattering Cross Sections

The inelastic electron scattering cross sections for the excitation of the levels in 18O lying below 6.0 MeV have been measured in the momentum transfer range 0.5 < q < 1.0 fm−1. Excitation of the following T = 1 levels was observed: 1.98 MeV (2+), 3.63 MeV (0+), 3.92 MeV (2+), 4.45 MeV (1−), 5.09 MeV (3−), 5.25 MeV (2+), and 5.33 MeV (0+). Estimates of transition probabilities to the ground state have been made through a parameterization of the data using the generalized Helm model. Longitudinal form factors calculated from the wave functions of Benson and Irvine show excellent agreement with the experimental form factors.

Study of charge transfer in FeTi

1983 ◽  
Vol 41 ◽  
pp. 296-297
Author(s):  
J. Taft∅
Keyword(s):  
Charge Transfer ◽  
Charge Distribution ◽  
Electron Scattering ◽  
Periodic System ◽  
Electron Distribution ◽  
Scattering Amplitude ◽  
Transition Elements ◽  
Hartree Fock ◽  
Cscl Structure ◽  
The Right

It is well known that for reflections corresponding to large interplanar spacings (i.e., sin θ/λ small), the electron scattering amplitude, f, is sensitive to the ionicity and to the charge distribution around the atoms. We have used this in order to obtain information about the charge distribution in FeTi, which is a candidate for storage of hydrogen. Our goal is to study the changes in electron distribution in the presence of hydrogen, and also the ionicity of hydrogen in metals, but so far our study has been limited to pure FeTi. FeTi has the CsCl structure and thus Fe and Ti scatter with a phase difference of π into the 100-ref lections. Because Fe (Z = 26) is higher in the periodic system than Ti (Z = 22), an immediate “guess” would be that Fe has a larger scattering amplitude than Ti. However, relativistic Hartree-Fock calculations show that the opposite is the case for the 100-reflection. An explanation for this may be sought in the stronger localization of the d-electrons of the first row transition elements when moving to the right in the periodic table. The tabulated difference between fTi (100) and ffe (100) is small, however, and based on the values of the scattering amplitude for isolated atoms, the kinematical intensity of the 100-reflection is only 5.10-4 of the intensity of the 200-reflection.

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.

Artefact in 20Å-Resolution Electron Images of Negatively Stained Twodimensional Membrane Protein Crystals

1982 ◽  
Vol 40 ◽  
pp. 92-93
Author(s):  
Douglas L. Dorset ◽  
Barbara Moss
Keyword(s):  
Electron Scattering ◽  
Cross Correlation ◽  
Transmission Function ◽  
Group Symmetry ◽  
Asymmetric Structure ◽  
Object Model ◽  
Phase Object ◽  
Computing Systems ◽  
Resolution Electron ◽  
Plane Group

A number of computing systems devoted to the averaging of electron images of two-dimensional macromolecular crystalline arrays have facilitated the visualization of negatively-stained biological structures. Either by simulation of optical filtering techniques or, in more refined treatments, by cross-correlation averaging, an idealized representation of the repeating asymmetric structure unit is constructed, eliminating image distortions due to radiation damage, stain irregularities and, in the latter approach, imperfections and distortions in the unit cell repeat. In these analyses it is generally assumed that the electron scattering from the thin negativelystained object is well-approximated by a phase object model. Even when absorption effects are considered (i.e. “amplitude contrast“), the expansion of the transmission function, q(x,y)=exp (iσɸ (x,y)), does not exceed the first (kinematical) term. Furthermore, in reconstruction of electron images, kinematical phases are applied to diffraction amplitudes and obey the constraints of the plane group symmetry.

Chemical modification of the bacterial wall to determine sites of metal deposition

1978 ◽  
Vol 36 (2) ◽  
pp. 350-351
Author(s):  
T. J. Beveridge
Keyword(s):  
Electron Scattering ◽  
Metal Salt ◽  
Metal Deposition ◽  
Suitable Model ◽  
X Ray Diffraction ◽  
Subtilis Cell ◽  
Thin Sections ◽  
X Ray ◽  
Section Data ◽  
Metal Impregnation

The Bacillus subtilis cell wall provides a protective sacculus about the vital constituents of the bacterium and consists of a collection of anionic hetero- and homopolymers which are mainly polysaccharidic. We recently demonstrated that unfixed walls were able to trap and retain substantial amounts of metal when suspended in aqueous metal salt solutions. These walls were briefly mixed with low concentration metal solutions (5mM for 10 min at 22°C), were well washed with deionized distilled water, and the quantity of metal uptake (atomic absorption and X-ray fluorescence), the type of staining response (electron scattering profile of thin-sections), and the crystallinity of the deposition product (X-ray diffraction of embedded specimens) determined.Since most biological material possesses little electron scattering ability electron microscopists have been forced to depend on heavy metal impregnation of the specimen before obtaining thin-section data. Our experience with these walls suggested that they may provide a suitable model system with which to study the sites of reaction for this metal deposition.

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