Physics Maths Engineering
Excitations of the nS States of Atomic Hydrogen by Electron Impact, Excitation Rate Coefficients, and Phase Shifts: Comparison with Positron Impact Excitation
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Anand K. Bhatia
Anand K. Bhatia
Heliophysics Science Division, NASA/Goddard Space Flight Center,
Related Subjects
Abstract
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 polarizedorbital method at various incident electron energies in the range 10 to 122 eV. Converged excitation cross-sections were obtained using sixteen partial waves (L = 0 to 15). Excitation cross-sections to 2S state, calculated earlier, were calculated at higher energies than before. Results obtained using the hybrid theory (variational polarized orbital method) are compared to those obtained using other approaches such as the Born–Oppenheimer, close-coupling, R-matrix, and complex-exterior scaling methods using only the spherical symmetric wave functions. Phase shifts and elastic cross-sections are given at various energies and angular momenta. Excitation rate coefficients were calculated at various electron temperatures, which are required for plasma diagnostics in solar and astrophysics to infer plasma parameters. Excitation cross-sections are compared with those obtained by positron impact excitation.
Key Questions
What is the focus of this study?
This study focuses on the excitation of the nS states of atomic hydrogen by electron impact, providing excitation rate coefficients and phase shifts. The results are compared with similar effects from positron impact excitation.
What are the nS states of atomic hydrogen?
The nS states refer to the quantum states of atomic hydrogen where the electron is in an orbital with an angular momentum quantum number (l) equal to 0 (spherical symmetry). These states are crucial for understanding atomic transitions and reactions involving hydrogen atoms.
What role do electron and positron impacts play in atomic hydrogen excitation?
Electron and positron impacts can excite the nS states of atomic hydrogen by transferring energy to the atom, leading to transitions to higher energy states. These interactions are fundamental in plasma physics, astrophysics, and the study of atomic collisions.
What are excitation rate coefficients and phase shifts?
Excitation rate coefficients measure the probability of excitation of an atomic state per unit time, while phase shifts describe the change in the wavefunction due to particle interactions. Both quantities are important for modeling atomic processes and energy transfer in atomic systems.
How does electron impact excitation compare with positron impact excitation?
The study compares electron and positron impacts on the excitation of nS states. While both types of impacts can cause excitation, positron impacts may lead to different outcomes due to the opposite charge of the positron compared to the electron, which can affect interaction cross-sections and energy transfer mechanisms.
What are the implications of this research?
This research provides a detailed comparison of electron and positron impacts on atomic hydrogen, contributing to a deeper understanding of atomic collisions and offering valuable data for fields like astrophysics, plasma physics, and atomic physics.
How does this study help in practical applications?
By determining excitation rate coefficients and phase shifts, the study helps improve models of plasma behavior, provides insights into astrophysical processes, and may contribute to the development of advanced materials and technologies that involve atomic interactions and collisions.
