Ion population fraction calculations using improved screened hydrogenic model withl-splitting

2018 ◽  
Vol 27 (10) ◽  
pp. 105201
Author(s):  
Amjad Ali ◽  
G Shabbir Naz ◽  
Rukhsana Kouser ◽  
Ghazala Tasneem ◽  
M Saleem Shahzad ◽  
...  
Keyword(s):  
Hydrogenic Model

Oxygen K near edge structures studied with multiple scattering calculations

1988 ◽  
Vol 46 ◽  
pp. 504-505
Author(s):  
Xudong Weng ◽  
Peter Rez
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Partial Cross Section ◽  
Energy Window ◽  
Edge Structure ◽  
Fine Structures ◽  
Hydrogenic Model ◽  
Electron Energy Loss ◽  
Quantitative Chemical

In electron energy loss spectroscopy, quantitative chemical microanalysis is performed by comparison of the intensity under a specific inner shell edge with the corresponding partial cross section. There are two commonly used models for calculations of atomic partial cross sections, the hydrogenic model and the Hartree-Slater model. Partial cross sections could also be measured from standards of known compositions. These partial cross sections are complicated by variations in the edge shapes, such as the near edge structure (ELNES) and extended fine structures (ELEXFS). The role of these solid state effects in the partial cross sections, and the transferability of the partial cross sections from material to material, has yet to be fully explored. In this work, we consider the oxygen K edge in several oxides as oxygen is present in many materials. Since the energy window of interest is in the range of 20-100 eV, we limit ourselves to the near edge structures.

SIGMAL: A Program for Calculating L-Shell lonization Cross-Sections

1981 ◽  
Vol 39 ◽  
pp. 198-199 ◽  
Author(s):  
R.F. Egerton
Keyword(s):  
Cross Sections ◽  
Fortran Program ◽  
Absorption Data ◽  
X Ray ◽  
Atomic Electrons ◽  
Energy Dependent ◽  
Hydrogenic Model ◽  
Electron Energy Loss ◽  
X Ray Absorption ◽  
Shell Ionization

SIGMAL is a short (∼ 100-line) Fortran program designed to rapidly compute cross-sections for L-shell ionization, particularly the partial crosssections required in quantitative electron energy-loss microanalysis. The program is based on a hydrogenic model, the L1 and L23 subshells being represented by scaled Coulombic wave functions, which allows the generalized oscillator strength (GOS) to be expressed analytically. In this basic form, the model predicts too large a cross-section at energies near to the ionization edge (see Fig. 1), due mainly to the fact that the screening effect of the atomic electrons is assumed constant over the L-shell region. This can be remedied by applying an energy-dependent correction to the GOS or to the effective nuclear charge, resulting in much closer agreement with experimental X-ray absorption data and with more sophisticated calculations (see Fig. 1 ).

PHONON BROADENING OF IMPURITY SPECTRAL LINES: II. APPLICATION TO SILICON

1963 ◽  
Vol 41 (11) ◽  
pp. 1823-1835 ◽  
Author(s):  
Robert Barrie ◽  
Kyoji Nishikawa
Keyword(s):  
General Theory ◽  
Spectral Lines ◽  
Deformation Potential ◽  
Phonon Interaction ◽  
Potential Description ◽  
Electron Phonon Interaction ◽  
Shallow Impurity ◽  
Hydrogenic Model ◽  
Numerical Estimations

The general theory of the phonon broadening of impurity spectral lines discussed in an earlier paper is applied to shallow impurity levels in silicon. With the use of a modified hydrogenic model and a deformation potential description of the electron–phonon interaction, expressions are obtained for typical contributions to the half-widths. Some numerical estimations are made for both acceptor and donor cases and are compared with experiment.

Analytical atomic hydrogenic model for calculation of plasma optical properties

2001 ◽  
Author(s):  
J. G. Rubiano ◽  
R. Rodriguez ◽  
J. M. Gil ◽  
F. H. Ruano ◽  
P. Martel ◽  
...  
Keyword(s):  
Optical Properties ◽  
Hydrogenic Model

The effect of a magnetic field on the impurity band density of states in the atomic limit

1982 ◽  
Vol 60 (12) ◽  
pp. 1743-1750 ◽  
Author(s):  
K. L. Liu ◽  
P. Modrak ◽  
B. Bergersen
Keyword(s):  
Magnetic Field ◽  
Density Of States ◽  
Gaussian Model ◽  
Impurity Band ◽  
Metal Insulator ◽  
Atomic Limit ◽  
Doped Silicon ◽  
Hydrogenic Model ◽  
Type Response ◽  
The Magnetic Field

A marked magnetic field dependence is found for the impurity band density of states in an idealized model of a doped semiconductor. The calculations are based on the Hubbard model in the atomic limit. We have obtained exactly the first eight moments of the distribution using a Gaussian model for the hopping integral, and the first seven moments with a hydrogenic model. A simple Zeeman type response of the spin system to the magnetic field is assumed. The predicted density of states is then obtained using a modified moment method with a trial density of states function obtained from the expected asymptotic behaviour of the distribution. Finally, we adjust the parameters of our models to correspond to phosphorous doped silicon below the metal insulator transition.

Impurity band density of states in the atomic limit

1980 ◽  
Vol 58 (8) ◽  
pp. 1142-1150 ◽  
Author(s):  
K. L. Liu ◽  
B. Bergersen ◽  
P. Modrak
Keyword(s):  
Density Of States ◽  
Gaussian Model ◽  
Impurity Band ◽  
Realistic Model ◽  
Model Calculations ◽  
Asymptotic Expressions ◽  
Atomic Limit ◽  
Diagrammatic Method ◽  
Transfer Integral ◽  
Hydrogenic Model

Model calculations are presented for the density of states in the impurity band of a semiconductor. The calculations are based on the Hubbard model in the atomic (i.e., infinite U) limit and are thus appropriate to impurity concentration below the critical one for the metal–insulator transition. No ordering of the electron spin is assumed, instead all spin configurations are taken to be equally probable. The impurity distribution is taken to be random. Calculations are carried out with a Gaussian overlap integral as a function of impurity–impurity distance and with the transfer integral obtained from hydrogenic wave function. The first seven moments of the density of states distribution of the Gaussian model and the first six moments of the hydrogenic model are calculated using a diagrammatic method. We also discuss asymptotic expressions for the distribution in the high and low density limits. Intepolation methods to reconstruct the distribution from the moments are investigated. It is believed that the methods used are suitable for generalizations to more realistic model Hamiltonians.

Improved Screened Hydrogenic Model

1996 ◽  
Author(s):  
Takeshi Nishikawa
Keyword(s):  
Hydrogenic Model

scholarly journals Raman Processes in the Helium Atom in Intense Fields

1975 ◽  
Vol 28 (1) ◽  
pp. 35
Author(s):  
RK Thareja ◽  
Man Mohan ◽  
V Nayak ◽  
SN Haque
Keyword(s):  
Helium Atom ◽  
General Expression ◽  
High Intensity ◽  
Transition Amplitude ◽  
Higher Order ◽  
Nonlinear Behaviour ◽  
S Wave ◽  
Intensity Parameter ◽  
Intense Fields ◽  
Hydrogenic Model

Using the hydrogenic model for the helium atom, the amplitude of transition from states He(ls) to He(ls, nl) by absorption of N photons of an intense field together with the emission of one Raman photon is evaluated. From the general expression for the transition amplitude, the particular case of transition from He(ls) to He(ls, 2p) is considered. The 'reduced' transition amplitude is plotted against the number of photons N involved and against the intensity parameter y st;parately. It is found that the s wave contributes maximaly to the transition amplitude. An important feature of the calculations is the appearance of nonlinear behaviour at high intensity. The dominance of higher order processes over lower ones at high intensity is also found.

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