A. K. Bhatia
YOU?
Author Swipe
View article: The Excitation of the 3D and 4D States of Atomic Hydrogen by Electron Impact
The Excitation of the 3D and 4D States of Atomic Hydrogen by Electron Impact Open
The excitation cross-sections of the 3D and 4D states of atomic hydrogen at low incident energies (from 0.90 to 5.00 Ry) were calculated using the variational polarized orbital method, which is also called the hybrid theory. Up to 12 parti…
View article: Werner Eissner (1930–2022): A Pioneer in Computational Atomic Physics
Werner Eissner (1930–2022): A Pioneer in Computational Atomic Physics Open
Werner Eissner (Figure 1), a pioneer in computational atomic physics, was born on 16 October 1930 in the city of Görlitz, Germany, to Bernhard and Frieda (née Eckert) Eissner [...]
View article: Excitation of the 2P State of Atomic Hydrogen by Electron Impact
Excitation of the 2P State of Atomic Hydrogen by Electron Impact Open
The excitation cross sections of the 2P state of atomic hydrogen at low incident electron energies (from 0.755 to 3.5 Ry) were calculated using the variational polarized orbital method. Up to 13 partial waves (L = 1, 13) were used to obtai…
View article: Superstructure and Distorted-Wave Codes and Their Applications
Superstructure and Distorted-Wave Codes and Their Applications Open
There have been many observations of the solar and astrophysical spectra of various ions. The diagnostics of these observations require atomic data that include energy levels, oscillator strengths, transition rates, and collision strengths…
View article: Comments on Computation of Free-Free Transitions in Atomic Physics
Comments on Computation of Free-Free Transitions in Atomic Physics Open
The amplitude T for ‘free-free’ processes such as bremsstrahlung or photoabsorption by an electron in the continuum in the presence of an external field, is usually written as the matrix element of the radiation operator taken between two …
View article: Photoejection from Various Systems and Radiative-Rate Coefficients
Photoejection from Various Systems and Radiative-Rate Coefficients Open
Photoionization or photodetachment is an important process. It has applications in solar- and astrophysics. In addition to accurate wave function of the target, accurate continuum functions are required. There are various approaches, like …
View article: Excitations of the nS States of Atomic Hydrogen by Electron Impact, Excitation Rate Coefficients, and Phase Shifts: Comparison with Positron Impact Excitation
Excitations of the nS States of Atomic Hydrogen by Electron Impact, Excitation Rate Coefficients, and Phase Shifts: Comparison with Positron Impact Excitation Open
The excitation cross-sections of the nS states of atomic hydrogen, n = 2 to 6, by electron impact on the ground state of atomic hydrogen were calculated using the variational polarized-orbital method at various incident electron energies i…
View article: Polarizabilities and Rydberg States in the Presence of a Debye Potential
Polarizabilities and Rydberg States in the Presence of a Debye Potential Open
Polarizabilities and hyperpolarizabilities, α1, β1, γ1, α2, β2, γ2, α3, β3, γ3, δ and ε of hydrogenic systems have been calculated in the presence of a Debye–Huckel potential, using pseudostates for the S, P, D and F states. All of these c…
View article: Interactions of Positrons with Matter and Radiation
Interactions of Positrons with Matter and Radiation Open
Positrons can be used to study metallic defects. Positron annihilation experiments have been carried out to identify the defects in complex oxides. Positrons have also been used to study the Bose–Einstein condensation (BEC). Ps-BEC can be …
View article: Scattering and Its Applications to Various Atomic Processes: Elastic Scattering, Resonances, Photoabsorption, Rydberg States, and Opacity of the Atmosphere of the Sun and Stellar Objects
Scattering and Its Applications to Various Atomic Processes: Elastic Scattering, Resonances, Photoabsorption, Rydberg States, and Opacity of the Atmosphere of the Sun and Stellar Objects Open
A scattering process can be a natural process or a process carried out in a laboratory. The scattering of particles from targets has resulted in important discoveries in physics. We discuss various scattering theories of electrons and posi…
View article: A Note on the Opacity of the Sun’s Atmosphere
A Note on the Opacity of the Sun’s Atmosphere Open
The opacity of the atmosphere of the Sun is due to processes such as Thomson scattering, bound–bound transitions and photodetachment (bound–free) of hydrogen and positronium ions. The well-studied free–free transitions involving photons, e…
View article: Resonances in Systems Involving Positrons
Resonances in Systems Involving Positrons Open
When an incident particle on a target gets attached to the target, the cross-section at that energy could be much larger compared to those at other energies. This is a short-lived state and decays by emitting an electron. Such states can a…
View article: Interactions of Positrons and Electrons with Hydrogenic Systems, Excitation, Resonances, and Photoabsorption in Two-Electron Systems
Interactions of Positrons and Electrons with Hydrogenic Systems, Excitation, Resonances, and Photoabsorption in Two-Electron Systems Open
There are a number of approaches to study interactions of positrons and electrons with hydrogenic targets. Among the most commonly used are the method of polarized orbital, the close-coupling approximation, and the R-matrix formulation. Th…
View article: Positron Impact Excitation of the nS States of Atomic Hydrogen
Positron Impact Excitation of the nS States of Atomic Hydrogen Open
The excitation cross sections of the nS states, n = 2 to 6, of atomic hydrogen at various incident positron energies (10.23 to 300 eV) were calculated using the variational polarized-orbital method. Nine partial waves were used to obtain c…
View article: Positron interactions
Positron interactions Open
As in the case of electrons, various interactions of positrons with atom, ions, molecules, and radiation are possible. There is no exchange between electrons and positrons. However, during scattering of positrons from targets, there is a p…
View article: Photodetachment of the Positronium Negative Ion with Excitation in the Positronium Atom
Photodetachment of the Positronium Negative Ion with Excitation in the Positronium Atom Open
Lyman-α radiation ( 2 P → 1 S ) has been seen from astrophysical sources and the sun. The line shape of this transition has been measured recently in Ps atoms both inside and outside a porous silica target. In the photodetachment of Ps−, t…
View article: Hybrid Theory of Scattering and Its Applications
Hybrid Theory of Scattering and Its Applications Open
A number of formulations have been used to investigate scattering of low-energy electrons and positrons from various targets. The hybrid theory of scattering, which takes into account the short-range as well as the long-range correlations,…
View article: Excitation of the 2S State of Atomic Hydrogen by Electron Impact
Excitation of the 2S State of Atomic Hydrogen by Electron Impact Open
The excitation cross sections of the 2S state of atomic hydrogen at 10 low incident electron energies (10.30 and 54.5 eV) have been calculated using the variational polarized method. Nine partial waves are used to get convergence of cross …
View article: P-Wave Positron-Hydrogen Scattering, Annihilation, and Positronium Formation
P-Wave Positron-Hydrogen Scattering, Annihilation, and Positronium Formation Open
In a previous paper (Bhatia A.K. 2016), a hybrid theory for the scattering of positrons from hydrogen atoms was applied to calculate S-wave phase shifts, annihilation, and positronium formation cross sections. This approach is now being ap…
View article: Positron-Hydrogen Scattering, Annihilation, and Positronium Formation
Positron-Hydrogen Scattering, Annihilation, and Positronium Formation Open
In previous papers (Bhatia A.K. 2007, 2012) a hybrid theory for the scattering of electrons from a hydrogenic system was developed and applied to calculate scattering phase shifts, Feshbach resonances, and photoabsorption processes. This a…
View article: Comments on Scattering of Electrons/Positrons by H-atoms and H\(_2\) Molecules under Weakly Coupled Plasmas
Comments on Scattering of Electrons/Positrons by H-atoms and H\(_2\) Molecules under Weakly Coupled Plasmas Open
In a recent publication by Modi et al. [Jour. of At. Mol. Cond. and Nano Phys. 2 (2015), 41], cross sections for the scattering of electrons and positrons from hydrogen atoms and molecules have been calculated in the Debye plasma, using th…
View article: Free-free Transitions of the Hydrogenic Systems Inside A Dense Plasma Irradiated by A Laser Field
Free-free Transitions of the Hydrogenic Systems Inside A Dense Plasma Irradiated by A Laser Field Open
In previous papers [Sinha and Bhatia, Phys. Rev. A 83, 063417 (2011), and Bhatia and Sinha, Phys. Rev. A 86, 053421 (2012)] cross sections for the freefree transitions are calculated for a low energy (external) electron hydrogen scattering…