Binary-encounter dipole model for positron-impact direct ionization

2019 ◽  
Vol 100 (6) ◽  
Author(s):  
Kamil Fedus ◽  
Grzegorz P. Karwasz
Keyword(s):  
Dipole Model ◽  
Positron Impact ◽  
Direct Ionization ◽  
Binary Encounter

scholarly journals Binary-Encounter Model for Direct Ionization of Molecules by Positron-Impact

Atoms ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 99
Author(s):  
Małgorzata Franz ◽  
Katarzyna Wiciak-Pawłowska ◽  
Jan Franz
Keyword(s):  
Cross Sections ◽  
Positron Impact ◽  
Standard Quantum ◽  
Direct Ionization ◽  
Wide Range ◽  
Small Set ◽  
The Cross ◽  
Ionization Cross Sections ◽  
Binary Encounter ◽  
Good Agreement

We introduce two models for the computation of direct ionization cross sections by positron impact over a wide range of collision energies. The models are based on the binary-encounter-Bethe model and take into account an extension of the Wannier theory. The cross sections computed with these models show good agreement with experimental data. The extensions improve the agreement between theory and experiment for collision energies between the first ionization threshold and the peak of the cross section. The models are based on a small set of parameters, which can be computed with standard quantum chemistry program packages.

Single ionization by positron impact

1996 ◽  
Vol 74 (7-8) ◽  
pp. 367-372 ◽  
Author(s):  
J. Moxom ◽  
P. Ashley ◽  
G. Laricchia
Keyword(s):  
Energy Range ◽  
Cross Sections ◽  
Positron Impact ◽  
Ionization Cross ◽  
Positron Scattering ◽  
Direct Ionization ◽  
Low Energies ◽  
Ionization Cross Sections ◽  
Impact Energies ◽  
Existing Data

The single direct ionization cross sections for positron scattering [Formula: see text] on He, Ar, Kr, and H2 were measured and compared with existing data and the corresponding cross sections for electron impact [Formula: see text]. At most impact energies the present data for He and H2 are in reasonable accord with other measurements and, in the case of He, with some of the available calculations. At low energies, [Formula: see text] is found to increase more slowly than [Formula: see text], probably due to the importance of Ps formation in this energy range.

Positron-impact direct ionization of lithium, sodium and potassium atoms

2021 ◽  
Vol 75 (10) ◽  
Author(s):  
R. Utamuratov ◽  
D. V. Fursa ◽  
A. S. Kadyrov ◽  
R. I. Campeanu ◽  
I. Bray ◽  
...  
Keyword(s):  
Positron Impact ◽  
Direct Ionization ◽  
Sodium And Potassium

Extension of the binary-encounter-dipole model to relativistic incident electrons

2000 ◽  
Vol 62 (5) ◽  
Author(s):  
Yong-Ki Kim ◽  
José Paulo Santos ◽  
Fernando Parente
Keyword(s):  
Dipole Model ◽  
Binary Encounter

A New Defect in Polyethylene Single Crystals

1973 ◽  
Vol 31 ◽  
pp. 70-71
Author(s):  
E. L. Thomas ◽  
S. L. Sass
Keyword(s):  
Single Crystals ◽  
Screw Dislocation ◽  
Small Distance ◽  
Dipole Model ◽  
Dislocation Dipole ◽  
Chain Folding ◽  
Black And White ◽  
Polymer Crystal ◽  
Different Types

In polyethylene single crystals pairs of black and white lines spaced 700-3,000Å apart, parallel to the [100] and [010] directions, have been identified as microsector boundaries. A microsector is formed when the plane of chain folding changes over a small distance within a polymer crystal. In order for the different types of folds to accommodate at the boundary between the 2 fold domains, a staggering along the chain direction and a rotation of the chains in the plane of the boundary occurs. The black-white contrast from a microsector boundary can be explained in terms of these chain rotations. We demonstrate that microsectors can terminate within the crystal and interpret the observed terminal strain contrast in terms of a screw dislocation dipole model.

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