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HYPERSPHERICAL COORDINATE THEORY OF PHYSICAL PROCESSES INVOLVING TWO-ELECTRON SYSTEMS
Abstract
In this dissertation, we investigate the two electron systems, H('-) and He, and their interaction with particles and with external fields using an adiabatic approximation in hyperspherical coordinates. Our first study concerns the wave functions, energies, and binding energies for the lowest singlet states of H('-) and He in uniform magnetic fields B < 10('9) G. A coupled expansion in one electron oblate spheroidal angle functions is used in order to treat the angular part of the wave functions. For the radial part of the wave functions, the separable, or adiabatic, approximation is employed. Results for energies and binding energies are comparable in accuracy with those obtained in variational calculations. The second study concerns the electron detachment cross section for collisions of 0.5 MeV H('-) projectiles on He targets. The first Born-approximation and the closure approximation are employed assuming that the H atom is left in the 1s state. Electron correlations within the H('-) system are treated in the adiabatic approximation including, for the first time for this problem, angular correlations. The first three partial wave components (i.e., s, p and d) of the detached electron are included. The calculated doubly differential cross section using an average He excitation energy, 35 eV, prescribed by Lee and Chen agrees well with experiment except at small detached electron angles where the discrepancy is attributed to excitations of the H atom which are not treated in our calculation. The final study concerns the photoionization cross section for H('-) and He using the single channel adiabatic approximation for both the initial and the final state. The cross sections for the processes H('-) + (gamma) (--->) H(1s) + e('-) and He + (gamma) (--->) He('+)(1s) + e('-) are calculated using the length formula as well as the acceleration formula. The cross sections using the length formula are found to be comparable with Stewart's variational calculation for H('-) and Samson's experimental value for He.
Subject Area
Atoms & subatomic particles
Recommended Citation
PARK, CHANG HWAN, "HYPERSPHERICAL COORDINATE THEORY OF PHYSICAL PROCESSES INVOLVING TWO-ELECTRON SYSTEMS" (1984). ETD collection for University of Nebraska-Lincoln. AAI8521471.
https://digitalcommons.unl.edu/dissertations/AAI8521471