Formation of ground and excited hydrogen atoms in proton–rubidium inelastic scattering

2016 ◽  
Vol 94 (4) ◽  
pp. 431-436
Author(s):  
S.A. Elkilany
Keyword(s):  
Inelastic Scattering ◽  
Cross Sections ◽  
Incident Energy ◽  
Computer Code ◽  
Inelastic Collisions ◽  
Hydrogen Atoms ◽  
Total Cross Sections ◽  
Rubidium Atoms ◽  
Wide Range ◽  
First Time

Inelastic collisions of protons with rubidium atoms are treated for the first time within the framework of the three channel coupled static, and frozen core approximations. The method is used for calculating partial and total cross sections with the assumption that only three channels (elastic; non-excited hydrogen, 1s-state; and excited hydrogen, 2s-state) are open. We have used the Lipmann–Schwinger equation and the Green’s functions iterative numerical method technique to solve the derived coupled integro-differential equations to obtain the computer code. The present results for total hydrogen formation cross sections are in agreement with results of other available ones in a wide range of incident energy.

Formation of ground and excited hydrogen atoms in proton–caesium inelastic scattering

2015 ◽  
Vol 93 (11) ◽  
pp. 1283-1291 ◽  
Author(s):  
S.A. Elkilany
Keyword(s):  
Inelastic Scattering ◽  
Cross Sections ◽  
Transition Matrix ◽  
Reasonable Agreement ◽  
Total Angular Momentum ◽  
Computer Code ◽  
Hydrogen Atoms ◽  
Static Approximation ◽  
Total Cross Sections ◽  
First Time

The inelastic scattering of a proton with a caesium atom is treated for the first time as a three-channel problem within the framework of the improved coupled static approximation with the assumption that the ground (1s state) and excited (2s state) hydrogen formation channels are open for seven values of the total angular momentum, [Formula: see text] at energies between 50 and 500 keV. The Green’s function iterative numerical method is used to obtain the computer code to calculate iterative partial cross sections. This can be done through calculating the reactance matrix at different values of considered energies to obtain the transition matrix that gives partial and total cross sections. Present results give reasonable agreement with previous results.

POSSIBLE POSITRONIUM FORMATION IN THE COLLISIONS OF POSITRONS WITH CALCIUM AND STRONTIUM POSITIVE IONS

2009 ◽  
Vol 23 (11) ◽  
pp. 2535-2549
Author(s):  
SALAH YASEEN EL-BAKRY
Keyword(s):  
Cross Sections ◽  
Incident Energy ◽  
Total Angular Momentum ◽  
Inelastic Collisions ◽  
Positronium Formation ◽  
Ionization Threshold ◽  
Scattering Problems ◽  
Total Cross Sections ◽  
Positive Ions ◽  
First Time

The inelastic collisions of positrons with calcium and strontium positive ions are treated for the first time as a three-channel problem within the framework of the improved coupled-static and frozen-core approximations with the assumption that the elastic, ground positronium and excited-positronium formation channels are open. The calculations of the partial and total cross sections are carried out for eight values of the total angular momentum ℓ (0 ≤ ℓ ≤7), at 20 values of the incident energy lying above the excited positronium formation threshold and extending to a wide region above the ionization threshold of the target ion. The total collisional positronium formation cross sections of e+– Sr + scattering show a peak around the ionization threshold of Sr + but display a peak at 30 eV for e+– Ca + scattering. In both scattering problems the total excited Ps formation cross sections have considerable values in the energy range [Formula: see text].

SENSITIZED FLUORESCENCE IN VAPORS OF ALKALI METALS: VII. ENERGY TRANSFER IN RUBIDIUM–CESIUM COLLISIONS

1966 ◽  
Vol 44 (4) ◽  
pp. 741-751 ◽  
Author(s):  
M. Czajkowski ◽  
D. A. McGillis ◽  
L. Krause
Keyword(s):  
Cross Sections ◽  
Alkali Metals ◽  
Dominant Role ◽  
Inelastic Collisions ◽  
Cesium Vapor ◽  
Rubidium Vapor ◽  
Total Cross Sections ◽  
Sensitized Fluorescence ◽  
Rubidium Atoms ◽  
Transfer Processes

Sensitized fluorescence in cesium vapor induced by collisions with excited rubidium atoms was investigated in order to determine the total cross sections for inelastic collisions between excited rubidium atoms and cesium atoms in their ground states. The partial pressure of the rubidium vapor in the Rb–Cs mixture was kept below 2 × 10−5 mm Hg in order to eliminate effects due to the trapping of the Rb resonance radiation. The collision cross sections for the various excitation transfer processes are as follows: Q12′(Rb 5 2P1/2 → Cs 6 2P3/2) = 1.5 Å2; Q11′(Rb 5 2P1/2 → Cs 6 2P1/2) = 0.5 Å2; Q22′(Rb 5 2P3/2 → Cs 6 2P3/2) = 0.9 Å2; Q21′(Rb 5 2P3/2 → Cs 6 2P1/2) = 0.3 Å2. The fact that the cross sections are considerably smaller than those for collisions between similar atoms indicates that the Rb–Cs interactions probably involve van der Waals' forces with a much shorter range than exchange forces, which play a dominant role in Rb–Rb or Cs–Cs collisions.

POSITRONIUM FORMATION CROSS-SECTIONS FOR POSITRON SCATTERING BY RUBIDIUM ATOMS

2007 ◽  
Vol 21 (02) ◽  
pp. 221-227 ◽  
Author(s):  
SALAH YASEEN EL-BAKRY
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Incident Energy ◽  
Total Angular Momentum ◽  
Low Energy ◽  
Positronium Formation ◽  
Positron Scattering ◽  
Total Cross Sections ◽  
Rubidium Atoms ◽  
Pronounced Peak

Cross-sections for positron-rubidium (37Rb) scattering have been calculated using the Clementi–Roetti wavefunctions and a combination of the coupled-static and frozen-core approximations. The total cross-sections, calculated with eight partial waves corresponding to the total angular momentum ℓ=0 to ℓ=7, are determined over a wide region of scattering energies ranging from 2.7 to 300 eV. The resulting total cross-sections are compared with experimental results and those calculated by other authors. Our total collisional cross-sections display a pronounced peak at 5 eV, nearly consistent with the measurements of Parikh et al. [Phys. Rev. A47, 1535 (1993)] and also reveal another peak at 7 eV, consistent with the experimental cross-section of Stein et al.23 in the neighborhood of 7 eV. The oscillating behavior of our total collisional cross-sections supports the possible existence of resonance, especially at low energy region. The effect of positronium formation on the total collisional cross-sections diminishes when the incident energy is larger than 100 eV.

Sensitized fluorescence in vapors of alkali metals. XI Energy transfer in potassium–rubidium collisions

1969 ◽  
Vol 47 (2) ◽  
pp. 215-221 ◽  
Author(s):  
E. S. Hrycyshyn ◽  
L. Krause
Keyword(s):  
Energy Transfer ◽  
Cross Sections ◽  
Alkali Metals ◽  
Inelastic Collisions ◽  
Rubidium Vapor ◽  
Total Cross Sections ◽  
Sensitized Fluorescence ◽  
Rubidium Atoms ◽  
Transfer Processes ◽  
Potassium Vapor

Sensitized fluorescence in rubidium vapor, induced by collisions with excited potassium atoms, was investigated to determine the total cross sections for inelastic collisions between excited potassium atoms and rubidium atoms in their ground states. The collision cross sections for the various excitation transfer processes are as follows: Q12′ (K42P1/2 → Rb52P3/2) = 40 Å2, Q22′ (K42P3/2 → Rb52P3/2) = 27 Å2, Q11′ (K42P1/2 → Rb52P1/2) = 2.7 Å2, and Q21′ (K42P3/2 → Rb52P1/2) = 1.9 Å2. The partial pressure of potassium vapor in the K–Rb mixture was kept largely below 10−5 mm Hg to eliminate effects due to the trapping of potassium resonance radiation.

Analysis of STEM micrographs of thick objects

1978 ◽  
Vol 36 (2) ◽  
pp. 106-107
Author(s):  
S. Golladay
Keyword(s):  
Inelastic Scattering ◽  
Multiple Scattering ◽  
Mass Distribution ◽  
Cross Sections ◽  
Phase Contrast ◽  
Image Point ◽  
Contrast Effects ◽  
Total Cross Sections ◽  
Elastic And Inelastic Scattering

The theory of multiple scattering has been worked out by Groves and comparisons have been made between predicted and observed signals for thick specimens observed in a STEM under conditions where phase contrast effects are unimportant. Independent measurements of the collection efficiencies of the two STEM detectors, calculations of the ratio σe/σi = R, where σe, σi are the total cross sections for elastic and inelastic scattering respectively, and a model of the unknown mass distribution are needed for these comparisons. In this paper an extension of this work will be described which allows the determination of the required efficiencies, R, and the unknown mass distribution from the data without additional measurements or models. Essential to the analysis is the fact that in a STEM two or more signal measurements can be made simultaneously at each image point.

Importance of coupling for inelastic collisions between protons and hydrogen atoms

1965 ◽  
Vol 283 (1392) ◽  
pp. 100-114 ◽  
Keyword(s):  
Cross Sections ◽  
Intermediate State ◽  
Relative Velocity ◽  
Inelastic Collisions ◽  
Hydrogen Atoms ◽  
Resonance Reactions ◽  
The Cross ◽  
Good Agreement

The importance of coupling for fast collisions between protons and hydrogen atoms is examined with the two-centred expansion in atomic eigenfunctions proposed by Bates (1958 a ). Cross-sections are evaluated for reactions H + + H (I s ) → H(I s ) + H + , H + + H( I s ) → H(2 s ) + H + , and H + + H(l a ) → H + + H(2 s ). The effect of a single intermediate state, either I s or 2 s , is considered. For the non-resonance processes, it is found that the cross-sections may be substantially increased by passage through intermediate state for incident energies less than about 10 keV, tending towards equality with decrease in relative velocity. Results obtained for the symmetrical resonance reactions are in good agreement with the two-state solutions of McCarroll (1961).

Sign in / Sign up

Export Citation Format

Share Document