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Theory of atomic hydrogen in a high uniform magnetic field and excitation and detachment of the hydrogen negative ion in fast collisions
Abstract
In this dissertation, we investigate two problems. First, atomic hydrogen in a uniform magnetic field using an adiabatic approximation in cylindrical coordinates. Second, fast H$\sp-$ collisions with He (treated in Born approximation) involving both detachment and excitation of the H atom to an excited state. Our first study concerns the wave functions, energies, and binding energies for the first Landau level in uniform magnetic fields B $>$ 10$\sp9$ G. Using only a single configuration wave function and no parameters, we present cylindrical adiabatic upper and lower bounds on the binding energies thus providing in one place stringent tests of past (and future) calculations. The second study concerns the electron detachment cross sections for collisions of 0.5 MeV H$\sp-$ projectiles on He targets. The first Born-approximation and the closure approximation are employed assuming that the H atom is left in either the 2s or 2p state. The calculations are carried out in the projectile frame and then transformed to the laboratory frame. The H$\sp-$ wave functions are represented by adiabatic approximation hyperspherical wave functions, which include a significant portion of the most important electron correlations. The first three partial wave components (i.e., s, p, and d) of the detached electron are included. Five H$\sp-$ excited channels, i.e., $\sp1$S$\pm$, $\sp1$P$\pm$ and $\sp1$D+, for involving the H atom in n = 2 excited states, are used in our calculations. The calculated doubly differential cross section using an average He excitation energy 35 eV, agree well with experimental data for $\theta$ = 0$\sp\circ$ involving the H atom excited to the 2p state. The details of the behavior of H$\sp-$ excitation and detachment doubly differential cross sections in the projectile frame including the $\sp1$P$\sp+$ shape resonance, the oscillatory behavior of the cross section as electron momentum k $\to$ 0, and the two types of asymptotic dipole potential are discussed in detail.
Subject Area
Atoms & subatomic particles
Recommended Citation
Liu, Chih-Ray, "Theory of atomic hydrogen in a high uniform magnetic field and excitation and detachment of the hydrogen negative ion in fast collisions" (1988). ETD collection for University of Nebraska-Lincoln. AAI8904496.
https://digitalcommons.unl.edu/dissertations/AAI8904496