Excitation of the 21S and 23S states of helium atoms by electron and hydrogen atom impact

1977 ◽  
Vol 55 (5) ◽  
pp. 396-402 ◽  
Author(s):  
Madeleine M. Felden ◽  
Marceau A. Felden
Keyword(s):  
Hydrogen Atom ◽  
Cross Sections ◽  
Ground State ◽  
Wave Functions ◽  
The Other ◽  
Helium Atoms ◽  
Atomic Wave ◽  
Excitation Cross Sections ◽  
The One ◽  
S States

Ochkur's approximation is used to analyse the excitation of 21S and 23S levels of helium atoms from the ground state by electron and hydrogen atom impact. Calculations are made with different atomic wave functions. To characterize the 11S and 21S states we use, on the one hand, the wave functions of Byron and Joachain, on the other hand, those of Hylleraas and Marriott and Seaton. For the 11S and 23S states, calculations are made firstly with the wave functions of Byron and Joachain and Morse, Young, and Haurwitz, secondly with those of Shull and Lödwin. Numerical values are tabulated and compared in each case. The discrepancies show the importance of the choice of atomic wave functions in the calculation of the excitation cross sections. Available experimental data and corresponding theoretical values obtained from other theories are plotted and compared with the present results.

scholarly journals On the Problem of He–He Bond in the Endohedral Fullerene He2@C60

2018 ◽  
Vol 63 (4) ◽  
pp. 288 ◽  
Author(s):  
G. A. Dolgonos ◽  
E. S. Kryachko ◽  
T. Yu. Nikolaienko
Keyword(s):  
Computer Simulation ◽  
Quantum Theory ◽  
Charge Transfer ◽  
Ground State ◽  
The Other ◽  
Endohedral Fullerene ◽  
Helium Atoms ◽  
Recent Developments ◽  
The One ◽  
Fullerene Stability

For more than twenty years, the endohedral fullerene cavity is attracting a permanent attention of experimenters and theorists, computational chemists and physicists, who apply their efforts to simulate encapsulated atoms and molecules in the fullerene cavity on computers and analyze the arising phenomena of atomic bonding. In this work, recent developments concerning the endohedral fullerene He2@C60, in particular, its experimental observation and relevant computational works, are reviewed. On the one hand, the dihelium He2 embedded into the C60 cavity is observed experimentally. On the other hand, the computer simulation shows that each of the He atoms is characterized by an insignificant charge transfer to C60, so that the He dimer exists as a partially charged (He+b)2 entity. The key issue of the work concerns the existence of a bond between those two helium atoms. Since the bond is created between two particles, we assert that it suffices to define the bond on the basis of the molecular L¨owdin’s postulate and use it to study the He dimer in the C60 cavity in terms of the He–He potential energy well. It was analytically demonstrated that this well can contain at least one bound (ground) state. Therefore, according to L¨owdin’s postulate, which is naturally anticipated in quantum theory, the conclusion is drawn that the (He+b)2 entity is a diatomic molecule, in which two heliums are bound with each other. On the basis of those arguments, the concept of endohedral fullerene stability is proposed to be extended.

Electron Excitation of 21S, 23S, 21P, and 23P States of Helium

1975 ◽  
Vol 53 (20) ◽  
pp. 2289-2295 ◽  
Author(s):  
H. G. P. Lins de Barros ◽  
H. S. Brandi
Keyword(s):  
Total Cross Section ◽  
Cross Section ◽  
Cross Sections ◽  
Scattering Amplitude ◽  
Theoretical Calculations ◽  
Electron Excitation ◽  
Wave Functions ◽  
Excitation Cross Sections ◽  
Characteristic Values ◽  
The One

Calculations for the total excitation cross sections of the 21S, 23S, 21P, and 23P states of He by electron impact have been carried out assuming the Born–Ochkur approximation for the scattering amplitude and a parametrization previously proposed by the authors for the total cross section. For the atomic wave functions we used LS coupling and obtained the one electron orbitals using the Xα method for three characteristic values of the parameter α. The results are compared with other experimental and theoretical calculations.

scholarly journals Intensities in Complex Spectra of Highly Ionized Atoms

1984 ◽  
Vol 86 ◽  
pp. 44-44
Author(s):  
M. Klapisch ◽  
A. Bar-Shalom ◽  
A. Cohen
Keyword(s):  
Cross Sections ◽  
Wave Functions ◽  
Coupling Scheme ◽  
Distorted Wave ◽  
Intermediate Coupling ◽  
Potential Wave ◽  
Excitation Cross Sections ◽  
Collisional Radiative Model ◽  
Radiative Model ◽  
Efficient Program

We describe a package of programs for the implementation of the collisional-radiative model to complex configurations. The number of levels taken into account may be several hundreds. The heart of the package is a very efficient program for excitation cross sections in the Distorted Wave framework, using the Relativistic Parametric Potential wave functions. The basic jj coupling scheme actually simplified the computations, enabling a useful factorization into radial and angular parts. Intermediate coupling and configuration interactions are accounted for. We computed ratios of intensities of 3d9 − 3d84s (E2) to 3d9 −3d84p (El) transitions as functions of ne and Te in Xe XXVIII and other Co-like spectra. The atomic model involves all the levels of configurations (3p6)3d9; −3d84s, −3d84p, −3d84d, −3d84f, and (3p5) −3d10, −3d94p. (275 levels) and all the transitions between them. Results compare very well with experimental spectra from TFR.

The Polarizability of Molecular Hydrogen H2

1936 ◽  
Vol 32 (2) ◽  
pp. 260-264 ◽  
Author(s):  
C. E. Easthope
Keyword(s):  
Wave Function ◽  
Perturbation Theory ◽  
Molecular Hydrogen ◽  
Applied Field ◽  
Minimum Energy ◽  
Wave Functions ◽  
The Other ◽  
System A ◽  
The One ◽  
Two Parameter

1. The problem of calculating the polarizability of molecular hydrogen has recently been considered by a number of investigators. Steensholt and Hirschfelder use the variational method developed by Hylleras and Hassé. For ψ0, the wave function of the unperturbed molecule when no external field is present, they take either the Rosent or the Wang wave function, while the wave functions of the perturbed molecule were considered in both the one-parameter form, ψ0 [1+A(q1 + q2)] and the two-parameter form, ψ0 [1+A(q1 + q2) + B(r1q1 + r2q2)], where A and B are parameters to be varied so as to give the system a minimum energy, q1 and q2 are the coordinates of the electrons 1 and 2 in the direction of the applied field as measured from the centre of the molecule, and r1 and r2 are their respective distances from the same point. Mrowka, on the other hand, employs a method based on the usual perturbation theory. Their numerical results are given in the following table.

scholarly journals Adhesive Distribution between Paper Components of Cigarettes

2003 ◽  
Vol 20 (6) ◽  
pp. 373-380
Author(s):  
B Kroell ◽  
S Starlinger ◽  
B Eitzinger
Keyword(s):  
Image Analysis ◽  
Mass Spectrometer ◽  
Cross Sections ◽  
Time Of Flight ◽  
Adhesive Layer ◽  
The Other ◽  
Tof Sims ◽  
Other Hand ◽  
The One ◽  
Secondary Ion

AbstractThe objective of this contribution is to characterise the distribution of adhesive between the plug wrap paper and the tipping paper on a finished cigarette. On the one hand, it is well known that this distribution influences various properties of the cigarette, but on the other hand, there are no methods available to completely determine this distribution. The area covered by adhesive, the amount of adhesive, and the thickness and position of the adhesive layer between the plug wrap and the tipping paper were chosen as essential quantities. Image analysis was used to evaluate the area covered by adhesive, and the amount of adhesive between the papers. The thickness and position of the adhesive layer were determined by processing pictures of paper cross-sections obtained with a time-of-flight secondary ion mass spectrometer (TOF-SIMS).

scholarly journals Results of calculations of atomic wave functions IV—Results for F - , Al +3 , and Rb +

1935 ◽  
Vol 151 (872) ◽  
pp. 96-105 ◽  
Author(s):  
Douglas Rayner Hartree
Keyword(s):  
Energy Parameter ◽  
Wave Functions ◽  
Numerical Accuracy ◽  
Radial Wave ◽  
Atomic Wave ◽  
Consistent Field ◽  
Self Consistent Field ◽  
The One ◽  
High Degree ◽  
Radial Wave Equation

In three previous papers, results of calculations of atomic wave functions, carried out by the method of the self-consistent field to a fairly high degree of numerical accuracy (for work of this kind), have been given for a number of atoms. The present paper gives further results of this kind for F - , Al +3 , and Rb + . Similar calculations are in progress for Ag + , and the results of the preliminary stages of the calculation have been given by Miss Black. The results here given are presented in the same form as in previous papers, namely:― (1) Unnormalized radial wave functions P, and the values of the normalization integral ∫ 0 ∞ P 2 dr , and of the energy parameter ε in the one-electron radial wave equation, for each function P; also values of P/ r l + 1 for small r .

The partial wave theory of electron-hydrogen atom collisions

1957 ◽  
Vol 53 (3) ◽  
pp. 654-662 ◽  
Author(s):  
I. C. Percival ◽  
M. J. Seaton
Keyword(s):  
Hydrogen Atom ◽  
Partial Wave ◽  
Cross Sections ◽  
Wave Theory ◽  
Wave Functions ◽  
Scattered Electron ◽  
Hartree Fock ◽  
Angular Momenta ◽  
Continuous State ◽  
Approximate Wave

ABSTRACTThe paper is concerned with the solution of the algebraic problems arising in the partial wave treatment of electron-hydrogen atom collisions. Explicitly antisymmetrized wave functions are used throughout. The boundary conditions are written in S-matrix notation and expressions for total and differential cross-sections obtained. The algebraic coefficients fλ and gλ occurring in the continuous state Hartree-Fock equations are expressed in terms of Racah coefficients, and tabulated as functions of the total angular momentum for atomic s, p and d electrons and all angular momenta of the scattered electron. Expressions are given for the calculation of first-order corrections to the results obtained using approximate wave functions.

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